Orthopaedic Knowledge Home Study by R. Alexander

Clinical Epidemiology: An Introduction Orthopaedic Knowledge Update 8 Table 1 | Main Design Characteristics of Diagnostic, Etiologic, Prognostic, and Therapeutic Studies Determinant(s) Outcome Occurrence Relation Domain General Factor(s) under study that are Health parameter (eg disease, Association between the Larger, theoretical population definition related to the outcome survival, complication, quality outcome occurrence and the to whom the study results occurrence of life) under study determinant(s) can be applied (generalized) Type of research Presence/absence of target Presence (prevalence) of Patients with particular disease disease in relation to symptom/sign suspected of Diagnostic Test results under study combination of test results particular disease research Incidence of disease under study Incidence of the outcome in Those potentially at risk to Etiologic Causal factor under study relation to the causal factor, develop the outcome at research Incidence of disease (eg, accounted for all possible interest disease, survival, confounders Prognostic Prognostic predictors under complication, quality of life) Patients potentially at risk to research study under study Incidence of the outcome in develop the outcome at relation to combination of interest Therapeutic Treatment (relative to a control Incidence of disease (eg, prognostic predictors research group) under study disease, survival, Patients with a particular complication, quality of life) Incidence of the outcome in disease for whom the under study relation to the treatment, treatment under study is accounted for all possible indicated confounders or extent to which a treatment improves the prognosis needs to be documented. From these empirical data, the (intended effect) and at what cost (such as treatment true nature and strength of the association between de- risks [unintended effects] and monetary costs). terminant and outcome is quantified. In medical practice, few outcomes are certain or To apply the findings with confidence in patient care, pathognomonic. Hence, the objective of clinical epide- the study results or estimated association need to be miologic research is to provide probabilistic knowledge generalized to a larger population (domain) from which on diagnosis, etiology, prognosis, and treatment of ill- the patients of the study population were selected. The nesses as a means to enhance patient care. The design, extent to which the results found in a particular study conduction, and data analysis of clinical studies on diag- population can be applied to a larger (theoretical) pa- nosis, etiology, prognosis, or treatment each have their tient population is called the generalizability of the own characteristics. study results. Basic Principles of Clinical Epidemiologic Therefore, regardless of the question studied, each Studies type of clinical epidemiologic study (diagnostic, etio- logic, prognostic, or therapeutic) has certain basic ele- Research Question, Study Population, ments: the occurrence relation, outcome, determi- nant(s), study population, and domain. These elements and Generalization are described later in this chapter according to each type of study and also are outlined in Table 1. Any research question related to patient care is either diagnostic, etiologic, prognostic, or therapeutic in na- Causal Versus Descriptive Research ture. Although each type of study has its own character- istics, every research question and thus each type of A major distinction first should be made between causal study addresses an association between the occurrence and descriptive epidemiologic research, because of the or probability of an outcome on one side and factors major consequences for study design, conduction, and that are related to this outcome occurrence on the other data analysis. The difference is directed by the determi- side. These factors are commonly called determinants. nant(s) under study. Although ‘determinant’ is a term Accordingly, central to clinical epidemiologic research is that seems to refer to factors that cause the occurrence the occurrence relation or the association between the of an outcome, it should be stressed that a determinant, outcome occurrence and its determinant(s). and therefore clinical epidemiologic research, may be causal or noncausal (descriptive). To quantify this relation requires empirical data, which in turn requires a study population. For each Causal studies quantify whether a specific determi- member or patient of the study population, both the nant is causally related to an outcome; for example, presence of the determinant(s) and of the outcome 110 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 10 Clinical Epidemiology: An Introduction trauma as a causal factor for vertebral fractures or im- from patient history (each question, including simple mobility as a causal factor for pulmonary embolism. The questions on age and sex, is a different diagnostic test), goal of causal studies is to explain the occurrence of an physical examination, and additional tests such as imag- outcome in relation to a causal determinant. Treatment ing, electrophysiology, and laboratory tests. Currently, studies are also causal studies. A treatment cannot be many diagnostic tests are used, sometimes with consid- effective if it does not interfere in some way in the erable burden to patients and health care budgets. causal pathway of the outcome, such as progress of the Therefore, it is important for physicians, patients, and disease or complications. A treatment is also a causal health care providers to know which additional tests determinant, although it does not induce outcome (such truly contribute to the distinction between disease pres- as trauma and immobility) but rather reduces the likeli- ence and absence beyond the information obtained hood or prevents the occurrence of outcomes. The fact from patient history and physical examination. Quanti- that therapeutic studies are causal studies is very impor- tative diagnostic research is needed to acquire this tant, as the design and data analysis of causal studies are knowledge. For example, a patient with low back pain quite different from the design and analysis of descrip- who is suspected of having a herniated disk (target dis- tive studies. ease) is referred to an orthopaedic surgeon. A possible diagnostic question could concern which results from In descriptive studies, the occurrence of the outcome the patient’s history (age, trauma, pain when seated) is only described by the determinant(s) at interest. The and from the physical examination (notably the Laségue motive of descriptive studies is to quantify whether a test) are relevant to predict or estimate the probability determinant predicts rather than explains the occur- of the presence of a herniated disk. Also, does the con- rence of the outcome. Causality is not investigated. Con- ventional radiograph of the lower back provide added sider, for example, a study to quantify whether the skin predictive value? color of a neonate (one of the items of the Apgar score) is predictive for its survival (a prognostic study ques- Occurrence Relation, Study Population, tion). Skin color obviously is not causally related to and Determinants mortality. Accordingly, prognostic research that does not The occurrence relation of a diagnostic study to answer involve questions about the effects of treatment is de- the above question would concern the frequency (or scriptive research. Diagnostic studies are descriptive as probability) of a herniated disk in relation to patient well. For example, in a patient who reports symptoms of history, physical examination, and radiographic results. a knee disorder, abnormalities on the MRI scan of the To study this relation, the study population should in- knee may predict the presence of knee arthrosis. Results clude a sufficient number of patients with low back pain of the MRI scan obviously are not the cause of the knee who have suspected disk herniation. Each patient arthrosis, but may predict the likelihood of the presence should undergo all diagnostic tests under study (all rele- or absence of the condition. vant tests indicated from patient history, physical exami- nation, and lower back radiography). These tests are Therefore, etiologic and therapeutic research ques- called the diagnostic determinants under study. tions address causality between a determinant and out- come. To answer these questions requires a causal study Outcome and Data Analysis design and causal data analysis. Diagnostic and prognos- Subsequently, each study patient should undergo the tic research questions address the predictive value be- reference or gold standard test to assess the patient’s di- tween determinants and outcome. Causality is not inves- agnostic outcome or “diagnostic truth.” The procedure tigated. To answer diagnostic and prognostic research that is used in practice (at the time of study initiation) questions requires a descriptive study design and corre- to ultimately determine the presence or absence of the sponding data analysis. The distinction between causal target disease, should be used as a reference standard in and descriptive research is further explained using clini- a scientific diagnostic study. In the example of the herni- cal examples in the next section. ated disk, MRI of the low back could be the reference standard. The results of the reference standard should Characteristics of Diagnostic, Etiologic, always be interpreted without knowledge of the diag- Prognostic, and Therapeutic Studies nostic tests or determinants under study, to prevent in- formation bias. Some diseases may lack a single refer- Diagnostic Research ence standard and sometimes it may be unethical or too costly to perform the reference standard in each patient. Diagnosis in practice starts with a patient presenting In such situations, a combination of tests or the so- with a particular set of symptoms or signs that lead the called consensus diagnosis is commonly used to deter- physician to suspect a particular disease, the so-called mine the diagnostic “truth” in each study patient. target disease. The goal of the physician is to estimate the probability of the presence of the underlying dis- ease. This probability is (often implicitly) estimated us- ing diagnostic test results. These test results are obtained American Academy of Orthopaedic Surgeons 111

Clinical Epidemiology: An Introduction Orthopaedic Knowledge Update 8 Documented patient data from the study in the ex- Occurrence Relation, Study Population, ample can then be used to quantify the probability of a and Determinants herniated disk in patients with particular symptoms and The occurrence relation of this study would be the oc- signs, and to quantify whether radiographs increase or currence (probability) of hip fractures in relation to the decrease this probability, and to what extent. The latter frequency of falling. To study this relation, for example, reflect the added value of the radiographs beyond the a group (cohort) of study subjects (men and women information obtained from the history and physical find- older than 70 years who have not had a hip fracture) ings. Causality between the determinants (test results) can be recruited and followed for a 5-year period. Each and outcome (final diagnosis) is not an issue. The only year, for example, the study subjects visit the research matter of importance is whether they predict the out- center so that the number of falls in the previous year come presence. Diagnostic research is therefore descrip- can be assessed. In contrast to diagnostic and prognostic tive or predictive research. To properly serve clinical studies, etiologic studies focus on the quantification of practice, diagnostic studies should address multiple de- the causal relation of a single determinant (falling) to terminants or tests rather than one single test. In prac- the outcome (hip fractures). tice, any diagnosis is rarely set by a single test. Results from patient history and physical examination will al- Outcome and Data Analysis ways be considered before additional tests are applied. During the study period, whether and when a hip frac- ture has occurred is documented for each subject. After Domain and Generalization the study period, the number of falls and whether a hip The domain or theoretical target population should be a fracture has occurred is known for each subject. In the defined group (such as all patients presenting in second- analysis, two determinant groups can be formed. One ary care with symptoms or signs indicative of herniated group includes subjects with a high frequency of falling disk) to which the results of the diagnostic study can be (on average three or more times per year) and the other generalized. In general, the domain of a diagnostic study with a low frequency (less than three times per year). is first of all determined by the symptoms and signs ex- Accordingly, whether the occurrence of hip fractures is hibited by the study patients. The domain definition of- significantly higher in those with high versus low num- ten includes the setting (primary, secondary, or tertiary ber of falls can be quantified. In addition, the data can care) as well. be analyzed using a cutoff value other than three, or us- ing more than two determinant groups (nonfallers, those The selection or recruitment of any study population with less than three falls, and those with more than is often restricted by logistic circumstances, such as ne- three falls per year). cessity of patients to live nearby the research center or the availability of time to participate in the study. These Domain characteristics, however, are unlikely to influence the The domain to which the study result can be generalized applicability and generalization of clinical study results. will include all patients older than 70 years with no his- It is important and challenging for the physician to ap- tory of a hip fracture. In general, the domain of an etio- preciate which characteristics truly affect the generaliz- logic study includes all persons who are potentially at ability of results obtained from a particular study popu- risk to develop the outcome at interest. As stated ear- lation. This appreciation usually requires external lier, other characteristics of the study population that knowledge of characteristics of the study population may affect the generalizability of the estimated associa- and of the research setting that may change the nature tion also need to be considered in the domain defini- and strength of the estimated associations between de- tion. Such generalization remains a matter of subjective terminant(s) and outcome. Therefore, generalizability or reasoning requiring external knowledge of the studied definition of the domain of a clinical study is not an ob- determinant-outcome or occurrence relation. jective process that can be framed in statistical terms. Generalizability is a matter of reasoning. Confounders In contrast to diagnostic and prognostic research, in eti- Etiologic Research ologic research the role of confounders is an additional issue that must be considered. Suppose the example Clinicians and epidemiologists seem to be most familiar study would yield an incidence of hip fractures (within 5 with etiologic research despite its limited direct rele- years) of 6% among the frequent fallers and 3% among vance to patient care and its methodologic complexities. the nonfrequent fallers. The initial conclusion would be The goal of etiologic studies is to quantify whether a that frequent falling causes a twofold increased risk of single, specific determinant is indeed causally related to hip fractures in subjects older than 70 years. This obser- the outcome under study. Consider, for example, a study vation, however, might not be true. The observed differ- to quantify whether frequent falling may cause hip frac- ence in frequency of hip fractures could be caused by tures in the elderly. 112 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 10 Clinical Epidemiology: An Introduction Table 2 | Hypothetical Example of the Distribution of Figure 1 Diagram to determine wheth- Various Potential Confounders Across Subjects With a High er a risk factor is a confounder of the (More Than Three Times Per Year) and Low (Less Than Three studied association. D = determinant; Times Per Year) Frequency of Falling O = outcome; C = potential confounder. 1 = the association between the poten- Confounder Low Frequency of High Frequency of tial confounder and the outcome; 2 = Falling Falling the association between the potential (n = 1,500) (n = 1,000) confounder and the determinant. Mean age (years) 74 83* Accounting for Confounders 35% 36% The most common and successful methods to account Current smoker 29 25* for confounding are randomization and adjustment in BMI (kg/m2) the analysis. Randomization means that the investigator randomly assigns the study subjects to the two (or *P value < 0.001 more) determinant groups. Because of this process, the two determinant groups are by definition comparable other risk factors that happened to be different across for all other risk factors except for the determinant at the two determinant groups. For example, it is known issue, given that the groups are large enough. Random- from the literature that increased age, smoking, and low ization, however, is frequently not feasible or ethical. In body mass index (BMI) are also risk factors for hip frac- the example study it is impossible to randomize subjects tures. If (by accident) in the study population these to frequent or nonfrequent falling groups. The same other risk factors are unequally distributed across the concept applies to causal studies investigating physio- two groups of fallers, the observed difference of 3% in logic determinants such as blood pressure, cholesterol hip fractures could be caused by these other risk factors. level, age, and bone mineral density. For ethical reasons, In etiologic research these other risk factors of the out- randomization is commonly not possible if the determi- come under study are called confounders. nant increases the risk of the outcome at interest. For example, when studying the causal relationship between Table 2 shows hypothetical results of the distribution smoking and lung cancer, or alcohol consumption and of the other three risk factors of hip fractures across the hip fractures, subjects cannot be randomly assigned to two groups of fallers. Age was significantly higher and years of smoking or alcohol consumption. Randomiza- BMI significantly lower among the frequent fallers, tion is only possible for causal determinants that reduce whereas the smoking distribution was the same. The the occurrence of the outcome at interest, and is mainly higher frequency of hip fractures among the frequent reserved for therapeutic determinants. Because thera- fallers could obviously not be caused by smoking (which peutic research is causal research, randomized studies was the same for both groups) but could be caused by particularly apply to therapeutic research. their higher age and lower BMI compared with the in- frequent fallers. In nonrandomized causal studies, accounting for confounding must be done in the data analysis. During Note that a risk factor can only be a true confounder the design phase, all potential risk factors of the out- in an etiologic study, if it indeed has a causal association come need to be defined beforehand such that associa- with the outcome, and is also (but not necessarily caus- tion 1 in Figure 1 is fulfilled. This identification of the ally) associated with the determinant. The latter simply potential risk factors should be based on existing knowl- means that the confounder is unequally distributed edge or “educated” reasoning. These other risk factors across the two determinant groups. This situation is should then be measured in each study subject in addi- schematically shown in Figure 1. If association 1 and 2 tion to the determinant of interest. In the analysis it exist in the data, C is a true confounder of the associa- should be assessed whether association 2 in Figure 1 is tion between determinant and outcome. Because the indeed present in the data. If so, a so-called multivari- goal of an etiologic study is to quantify whether there is able analysis is applied to adjust the crude association a causal association between the determinant (falling) between the determinant and outcome (a difference of and outcome (hip fractures), the influence of any other 3% hip fractures in the example) for all confounders. A risk factors that might confound this estimation must be determinant is called causally associated with an out- ruled out or accounted for. If confounders are not ac- come, if the association remains after having accounted counted for in an etiologic study, then an observed asso- for all confounders in the data. ciation might not be the true association, and is there- fore invalid. The association between the causal Note that adjustment for confounding might dilute determinant and outcome without adjusting for con- but could also increase the crude association between founders is called the crude association. 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Clinical Epidemiology: An Introduction Orthopaedic Knowledge Update 8 the determinant and outcome, depending on the distri- Occurrence Relation, Study Population, bution of the confounders across the determinant cate- and Determinants gories and whether the confounder is a risk factor or The occurrence relation of a prognostic study to answer preventive factor of the outcome. In the example study, this example question would be the frequency (or prob- adjustment for age and BMI would dilute the crude as- ability) of postoperative nausea and vomiting within sociation of 3% difference in hip fractures because in- 24 hours in relation to multiple preoperative patient creased age and low BMI both increase the occurrence characteristics, such as planned duration of surgery, age, of hip fractures, and the frequent fallers were on aver- sex, history of postoperative nausea and vomiting, and age older and leaner than the nonfrequent fallers. Stud- smoking status. The study population could include pa- ies whose purpose is to quantify whether an unintended tients at a particular hospital undergoing any ortho- effect of a treatment is truly caused by that treatment paedic surgery who are at risk of developing postopera- are etiologic studies as well and should follow the above tive nausea and vomiting. All prognostic predictors of principles. the outcome should be documented from each study pa- tient. Similarly, as in diagnostic research, prognostic re- Prognostic Research search should address multiple predictors rather than a single prognostic predictor because in practice, no prog- Prognostic research has received limited attention in ap- nosis is set by a single predictor. plied medical research. In practice, to set a prognosis is to estimate the probability that a patient with a particu- Outcome and Data Analysis lar illness and clinical and nonclinical profile will de- Each patient should be followed up to measure whether velop a particular outcome (death, a complication, re- the outcome has occurred. In the example, this measure- currence of disease, or a good quality of life) within a ment is done at 24 hours after surgery, using a simple certain period of time. The prognostic probability could questionnaire. As with diagnostic research, the person also be estimated given that the patient has undergone a measuring the outcome must be blinded to the patient’s particular treatment. Here, treatment is considered as predictor values to prevent information bias. Particu- one of the prognostic factors. Prognosis in practice does larly in prognostic (and therapeutic) research, outcomes not simply imply the typical course of an illness or diag- that are important to patients (such as degree of pain nosis; it refers to the course of a patient with particular and quality of life issues) should be investigated. Re- clinical and nonclinical characteristics. Just as with diag- searchers too often rely on so-called proxy outcomes nostic questions, it is relevant for physicians to know such as duration of intensive care stay or intraopera- which information is truly needed to estimate a patient’s tively measured physiologic parameters such as body prognosis. As with diagnosis, the probability should pref- temperature or blood pressure rather than on patient erably be estimated with information or determinants outcomes. that are easily obtainable from the patient using nonin- vasive, low-cost methods. The principles of design and The preoperative predictors that truly have predic- analysis of prognostic research are similar to those of di- tive value (that is, may predict the occurrence of postop- agnostic research, because both can be grouped under erative nausea and vomiting within 24 hours) and which the heading of descriptive or prediction research. Their information actually is redundant to determine the pa- study goal is to quantify the predictive association be- tient’s prognosis can be easily quantified from the data. tween the determinant(s) and the outcome; causal ex- planation of the outcome is not necessary. Domain In general, the domain of a prognostic study is deter- An example of a prognostic question is whether pre- mined by the diagnosis or illness that places the patient operative patient characteristics are predictive for the at risk of developing the outcome at interest. As with di- occurrence of postoperative nausea and vomiting within agnostic research, the setting (for example, primary or 24 hours in patients undergoing orthopaedic surgery. If secondary) is often included if it is not inherent to the this occurrence can be estimated preoperatively, prefer- study population. Similarly, other characteristics of the ably using easily obtainable patient variables, the anes- study population that may affect the generalizability of thesiologist or orthopaedic surgeon could perform a the estimated association also need to be included. The timely intervention in high-risk patients to reduce the domain of the example study would include all patients risk of postoperative nausea and vomiting. For example, scheduled for orthopaedic surgery. However, there may instead of using isoflurane, desflurane, or sevoflurane be no reason to assume that the predictors estimated for general anesthesia, intravenous propofol, which has from the orthopaedic study population would not also been proven to cause less postoperative nausea and apply to other surgical patients. Therefore, the results of vomiting could be used, or preemptive administration of the example study could perhaps be generalized to all antiemetics could be done. types of surgery. However, as discussed previously, this generalization requires external knowledge and subjec- 114 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 10 Clinical Epidemiology: An Introduction tive judgment. The question to be asked is whether in served outcome could be caused by other factors such these other types of surgery that were not included in as natural course or, because the patient is aware of the the study population the same predictors would be treatment, change in patient perception and lifestyle found with the same predictive values. changes that might influence the outcome occurrence. The latter is particularly the case when the study out- The example study shows that as with diagnostic re- come is a subjective outcome requiring patient report- search, prognostic studies (apart from studies on treat- ing, such as pain and quality of life. If the outcome, for ment effects) aim to describe or predict the occurrence example, is death, factors such as patient perception and of a future outcome and possible given combinations of lifestyle changes have much less influence on the out- prognostic determinants. Causality between the deter- come. In situations in which an extreme change in out- minants and outcome is not at issue. A similar approach come is observed that is unlikely to be related to other as that described above has been applied to predict the factors, a controlled study may not be necessary. This sit- need for intraoperative blood transfusion in orthopaedic uation, however, is rare in medicine. However, it may, and other types of surgery. for example, apply to the benefits of total hip replace- ment, which leads to such a dramatic change in mobility Therapeutic Research of a patient that the result can validly be assumed to be the consequence of the intervention. Generally, how- Studies to quantify the intended effect of a treatment, ever, the determinant in a therapeutic study includes a including surgical treatment (further referred to as ther- group that receives the treatment (index group) and a apeutic or intervention studies) are the most popular control group that does not. form of clinical epidemiologic research. The methods for design and analysis of intervention studies, including the The control group may receive either placebo treat- well-known Consolidate Standards of Reporting Trials ment or an existing treatment. A placebo treatment is (CONSORT), has been extensively documented in the exactly the same as the index treatment except that it literature. The principles of therapeutic research can be does not include the effective part or substance of the described by considering the following example of a treatment. Placebo treatment for a control group is study question: does arthroscopic débridement in pa- common for drug therapies, but is also possible for non- tients with osteoarthritis of the knee reduce the occur- pharmacologic or surgical interventions. The placebo rence of pain? drug has the same color, size, taste, or mode of use as the index drug, except that it does not include the phar- The question of how the clinical course of a patient macologic substance. Administering one half of the with a particular illness and manifestations can be modi- study population the index and the other half the pla- fied indicates that therapeutic research is a form of cebo treatment, and blinding the patient to the received prognostic research. As stated earlier, the goal of a ther- treatment, excludes the influence of many factors that apeutic study is to quantify whether an observed in- could influence the difference in outcome between the tended effect is truly caused by the treatment under two groups. These factors include patient perception and study, excluding any other causes. Therapeutic studies lifestyle changes but also treatment-related factors such are also a form of causal research and the characteristics as taste, size, or mode of use of a drug. As both patient described for etiologic research similarly apply to inter- groups are unaware of the received treatment, the ex- vention research. tent to which these factors operate will be the same across both groups and cannot cause any differences in Occurrence Relation and Study Population outcome occurrence. The occurrence relation of the example study question (regarding patients with osteoarthritis of the knee) However, the use of a placebo treatment is not al- would be the average level of pain at 24 months postop- ways feasible or ethical, especially for surgical therapies. eratively in relation to arthroscopic débridement. Study For example, when quantifying the effect of coronary ar- subjects could include men and women of all ages, with tery bypass grafting (CABG) it would be unethical to osteoarthritis of the knee who have an indication for ar- perform a placebo-CABG. Placebo-CABG would in- throscopy. The study subjects could be selected from volve the same procedure as the index-CABG, including four different hospitals, for example. undergoing general anesthesia plus sternotomy, but without the bypassing which is in fact the effective Determinant (‘pharmacologic’) substance of the CABG treatment. Proper definition of the determinant in therapeutic Treatments or diseases that do not allow for a placebo studies requires some explanation. To quantify the effect comparison require comparison with an existing treat- of a treatment always requires a control group. A single ment. Existing treatment also could be no treatment group of patients that has been treated with the inter- (wait and see). vention under study, a so-called case series, is insuffi- cient to properly quantify the treatment effect. Any ob- Besides ethical constraints, using an existing treat- ment as a control might also be favored to better reflect American Academy of Orthopaedic Surgeons 115

Clinical Epidemiology: An Introduction Orthopaedic Knowledge Update 8 clinical practice. Using an existing treatment as control Domain implies that all patients are aware of the received treat- The domain to which the results of the example study ment; the patients are not ‘blinded’. The influence of pa- can be generalized are patients who have osteoarthritis tient perception, lifestyle changes, and treatment factors and an indication for arthroscopy. other than the effective part, may thus be different across the new (index) and existing (control) treatment Therapeutic research is causal research on the in- groups. However, all of these factors are considered as tended effects of treatments. The treatment under study part of the total effect of each treatment strategy on the may be compared with existing treatment including no outcome. It merely reflects the real life situation of both treatment, or to a placebo treatment, depending on the treatments. Any difference in outcome between the two research question. A pragmatic study approach will treatment groups will result from the overall difference quantify the difference in effect between two treatment between the two treatment strategies. It will be impossi- strategies. A placebo-controlled study quantifies the ef- ble to unravel which factors are responsible for the ob- ficacy of the effective (pharmacologic) substance of the served difference. Therapeutic studies using another treatment under study. Blinding the patient is only at is- (nonplacebo) treatment as control are called pragmatic sue in placebo-controlled studies. In pragmatic and studies. Placebo-controlled therapeutic studies are placebo-controlled studies, the treatments always should called explanatory studies, as any observed difference be allocated randomly to prevent confounding bias. If can be attributed to or explained by the difference in patient numbers are low, adjustment for confounding in ‘effective substance’ between the two groups. the analysis may sometimes be necessary. Blinding the observer to the outcome is always desired except when In the example, if a pragmatic trial would be desired, the outcome under study is not sensitive to observer in- the determinant could include arthroscopy débridement terpretation. versus no treatment (or wait and see). If a placebo- controlled study would be desired, the control group Summary would include placebo arthroscopy, that is, without débridement. Such a study has recently been conducted. Clinical epidemiology attempts to provide quantitative answers to relevant questions to improve future medical Outcome care. Such questions arise from the patient-physician en- In the example study, the outcome is pain measured, for counters and require either diagnostic, etiologic, prog- example, 1 and 2 years after surgery using a visual ana- nostic, or therapeutic knowledge. Accordingly, the first log or verbal rating scale. As with prognostic research, step when designing a clinical epidemiologic study is to patient-driven rather than intermediate outcomes determine which of these four types of knowledge is ad- should be chosen. Furthermore, as in all other types of dressed. Irrespective of the type of knowledge ad- research, the person who measures the outcome should dressed, definition of the occurrence relation, outcome, be blinded to the treatment of the patient to prevent in- and determinant applies to each type of study question. formation bias, whether or not a pragmatic or placebo- With etiologic or therapeutic research, the potential controlled therapeutic study is performed. confounders of the determinant-outcome relationship should also be defined beforehand. It is also useful to Data Analysis and Confounding initially define the domain of the studied occurrence re- As mentioned earlier, one of the most important aspects lation because this process helps to select the suitable of causal research is to account for other risk factors of study population from that domain. Next, the determi- the outcome (such as confounders). Randomization is nant(s), confounders, and outcome should be measured the best method to ensure that the compared groups are from each study subject. Finally, the data should be ana- comparable on all risk factors except for the determi- lyzed, taking into account whether the goal is to predict nant under study. In therapeutic research, the benefits the outcome (diagnostic or prognostic research) or to of the determinant (treatment) are supposed to out- explain what actually causes the occurrence of the out- weigh its risks, making randomization feasible and ethi- come (etiologic or therapeutic research). cal. Nevertheless, despite adequate randomization, an imbalance of confounders between the two treatment Annotated Bibliography groups could still occur by chance, particularly when the number of patients is small. Therefore, in the analysis, General Reference investigators should first check other risk factors of the outcome to determine if they are indeed equally distrib- Greenhalgh T: How to Read a Paper: The Basics of Evi- uted. If not, adjustment in the analysis may sometimes dence Based Medicine, ed 2. London, England, BMJ be needed to account for confounding. Publishing Group, 2001. This book provides a general introduction on the essen- tials of evidence-based medicine and guidelines for reading clinical epidemiologic studies. 116 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 10 Clinical Epidemiology: An Introduction Laupacis A: The future of evidence-based medicine. Can Characteristics of Etiologic Studies J Clin Pharmacol 2001;8(suppl A):6A-9A. Hak E, Verheij TJ, Grobbee DE, Nichol KL, Hoes AW: This article presents a state of the art review of evidence- Confounding by indication in non-experimental evalua- based medicine and the challenges for the near future. tion of vaccine effectiveness: The example of prevention of influenza complications. J Epidemiol Community Clinical Epidemiologic Research Questions Health 2002;56:951-955. Sackett DL: Clinical epidemiology: What, who, and This article illustrates the problems of using data from a whither. J Clin Epidemiol 2002;55:1161-1166. nonrandomized (observational) study to quantify the effec- tiveness of a therapy. A general introduction to the history of clinical epidemiol- ogy is presented. Kennedy KA, Frankowski RF: Evaluating the evidence about therapies: What the clinician needs to know about Basic Principles of Clinical Epidemiologic Studies statistics. Clin Perinatol 2003;30:205-215. Rothman KJ: Epidemiology: An Introduction. Oxford, The basics of data analysis of therapeutic studies is ad- England, Oxford University Press, 2002. dressed in this article. This book, which focuses on etiologic research, covers the Lorenz JM, Paneth N: When are observational studies field of epidemiology including history, study questions, and adequate to assess the efficacy of therapeutic interven- data analysis. A background in epidemiology is required. tions? Clin Perinatol 2003;30:269-283. Characteristics of Diagnostic Studies This article presents information on when and how non- randomized (observational) study data can be useful to quan- Bossuyt PM, Reitsma JB, Bruns DE, et al: Towards com- tify the effectiveness of therapies. plete and accurate reporting of studies of diagnostic ac- curacy: The STARD initiative: Standards for Reporting Characteristics of Prognostic Studies of Diagnostic Accuracy. Clin Chem 2003;49:1-6. Concato J: Challenges in prognostic analysis. Cancer This article addresses a list of criteria that will enhance the 2001;91(suppl 8):1607-1614. reporting and conduction of diagnostic accuracy studies. This article enhances the understanding of studies that at- Knottnerus JA: The Evidence Base of Clinical Diagno- tempt to quantify the prognostic or predictive value of factors sis. London, England, BMJ Publishing Group, 2002. such as patient characteristics, etiologic factors, and diagnostic tests and results. This book contains a series of British Medical Journal arti- cles on the essentials of diagnostic studies, from study ques- van Klei WA: Moons KG, Leyssius AT, Knape JT, Rut- tions to analysis. ten CL, Grobbee DE: Reduction in type and screen: Preoperative prediction of RBC transfusions in surgery Moons KG, Grobbee DE: Diagnostic studies as multi- procedures with intermediate transfusion risks. Br J variable, prediction research. J Epidemiol Com Health Anaesth 2001;87:250-257. 2002;56:337-338. This article presents an example study that developed an A brief report discussing the need for studies that attempt easy applicable prognostic rule for surgeons or anesthesiolo- to quantify the added value of new tests beyond existing tests gists to preoperatively predict which surgical patients would (rather than estimating a test’s sensitivity and specificity) is undergo perioperative blood transfusions. presented. Moons KG, Harrell FE: Sensitivity and specificity van Klei WA, Moons KG, Rheineck-Leyssius AT, et al: should be deemphasized in diagnostic accuracy studies. Validation of a clinical prediction rule to reduce preop- Acad Radiol 2003;10:670-672. erative type and screen procedures. Br J Anaesth 2002; 89:221-225. This editorial on the Standards for Reporting of Diagnos- tic Accuracy initiative discusses why estimating a test’s sensi- This article presents an example study that validated a de- tivity has limited value for clinical practice. veloped prognostic rule to preoperatively predict which new surgical patients would undergo perioperative blood transfu- Oostenbrink R, Moons KG, Bleeker SE, Moll HA, sions. Grobbee DE: Diagnostic research on routine care data: Prospects and problems. J Clin Epidemiol 2003;56:501- Vergouwe Y, Steyerberg EW, Eijkemans MJ, Habbema 506. JD: Validity of prognostic models: When is a model clin- ically useful? Semin Urol Oncol 2002;20:96-107. This article addresses the pros and cons of using routine care data for the evaluation of diagnostic tests. This article discusses an appealing method to determine whether a prognostic prediction rule is clinically useful. American Academy of Orthopaedic Surgeons 117

Clinical Epidemiology: An Introduction Orthopaedic Knowledge Update 8 Characteristics of Therapeutic Studies Guyatt GH, Sackett DL, Cook DJ: Users’ guides to the medical literature: II. How to use an article about ther- Altman DG, Schulz KF, Moher D, et al: The revised apy or prevention: B. What were the results and will CONSORT statement for reporting randomized trials: they help me in caring for my patients?: Evidence- Explanation and elaboration. Ann Intern Med 2001;134: Based Medicine Working Group. JAMA 1994;271:59-63. 663-694. Hennekens CE, Buring JE: Epidemiology in Medicine. This article addresses a list of criteria that will enhance the Boston, Massachusetts, Little, Brown & Co, 1987. reporting and conduction of randomized therapeutic studies. Helms PJ: Real world pragmatic clinical trials: What are Jaeschke R, Guyatt GH, Sackett DL: Users’ guides to they and what do they tell us? Pediatr Allergy Immunol the medical literature: III. How to use an article about a 2002;13:4-9. diagnostic test: A. Are the results of the study valid?: Evidence-Based MedicineWorking Group. JAMA 1994; This article presents a clear explanation of the differences 271:389-391. between explanatory (such as placebo-controlled) randomized therapeutic studies and pragmatic randomized therapeutic Laupacis A, Sekar N, Stiell IG: Clinical prediction rules: studies. A review and suggested modifications of methodologi- cal standards. JAMA 1997;277:488-494. Moher D, Schulz KF, Altman D: The CONSORT state- ment: Revised recommendations for improving the Laupacis A, Wells G, Richardson WS, Tugwell P: Users’ quality of reports of parallel-group randomized trials. guides to the medical literature: V. How to use an article JAMA 2001;285:1987-1991. about prognosis: Evidence-Based Medicine Working Group. JAMA 1994;272:234-237. This article addresses a list of criteria to enhance the re- porting and conduction of randomized therapeutic studies. Levine M, Walter S, Lee H, Haines T, Holbrook A, Moyer V: Users’ guides to the medical literature: IV. Moseley JB, O’Malley K, Petersen NJ, et al: A con- How to use an article about harm: Evidence-Based trolled trial of arthroscopic surgery for osteoarthritis of Medicine Working Group. JAMA 1994;271:1615-1619. the knee. N Engl J Med 2002;347:81-88. McAlister FA, Graham I, Karr GW, Laupacis A: A good example of an explanatory (such as placebo- Evidence-based medicine and the practicing clinician. controlled) therapeutic study of a surgical intervention is pre- J Gen Intern Med 1999;14:236-242. sented. Moons KG, van Es GA, Michel BC, Buller HR, Classic Bibliography Habbema JD, Grobbee DE: Redundancy of single diag- nostic test evaluation. Epidemiology 1999;10:276-281. Apfel CC, Laara E, Koivuranta M, Greim CA, Roewer N: A simplified risk score for predicting postoperative Randolph AG, Guyatt GH, Calvin JE, Doig G, Richard- nausea and vomiting: Conclusions from cross-validation son WS: Understanding articles describing clinical pre- between two centers. Anesthesiology 1999;91:693-700. diction tools. Crit Care Med 1998;26:1603-1612. Charlton BG: Understanding randomized controlled tri- Reichenbach H: The Rise of Scientific Philosophy. New als: Explanatory or pragmatic? Fam Pract 1994;11:243- York, NY, Harper Row, 1965. 244. Roland M, Torgerson DJ: What are pragmatic trials? Evidence-Based Medicine Working Group: Evidence- BMJ 1998;316:285. based medicine: A new approach to teaching the prac- tice of medicine. JAMA 1992;268:2420-2425. Sackett DL, Haynes RB, Tugwell P: Clinical Epidemiol- ogy: A Basic Science for Clinical Medicine. Boston, Mas- Grobbee DE, Miettinen OS: Clinical Epidemiology: In- sachusetts, Little, Brown & Co, 1985. troduction to the discipline. Neth J Med 1995;47:2-5. Sackett DL, Rosenberg WM, Gray JA, Haynes RB, Ri- Guyatt GH, Sackett DL, Cook DJ: Users’ guides to the chardson WS: Evidence based medicine: What it is and medical literature: II. How to use an article about ther- what it isn’t. BMJ 1996;312:71-72. apy or prevention: A. Are the results of the study valid?: Evidence-Based Medicine Working Group. JAMA 1993; Tinetti ME, Liu WL, Claus EB: Predictors and prognosis 270:2598-2601. of inability to get up after falls among elderly persons. JAMA 1993;269:65-70. 118 American Academy of Orthopaedic Surgeons

Chapter 11 Musculoskeletal Imaging John A. Carrino, MD, MPH William B. Morrison, MD Available Imaging Modalities try rotation intervals combined with multiple detectors providing increased coverage along the z-axis. Currently All medical imaging modalities that are available clini- there are configurations with up to 64 channel detectors cally have musculoskeletal applications. There have available. The data from a multislice CT scanner can be been significant technologic advancements in the areas used to generate images of different thickness from the of radiography, CT, ultrasound, nuclear medicine, and same acquisition. The minimum section thickness is re- MRI. duced to approximately 0.5 mm and images can be re- constructed at this 0.5-mm interval. Isotropic (equal di- Radiography mension) voxels measuring 0.5 mm in x, y, and z directions greatly improve the spatial resolution and the Digital radiography exists in the form of computed radi- quality of reconstructing algorithms, allowing generation ography or direct radiography. Image processing and dis- of exquisite multiplanar reformats (Figure 1) and three- tribution is achieved through a picture archiving and com- dimensional images. These three-dimensional image munication system. The images can be placed on a processing and display techniques are particularly useful compact disk with an imbedded viewer. The widespread for regions of complex anatomy such as the pelvis, or availability of computers with compact disk readers allows for bones for which it is difficult to obtain isolated pro- this method of image processing to be a more portable jections without overlap, such as the scapula or the cer- mechanism of transporting and managing images. View- vical spine (Figure 2). Multiplanar reformats can be cre- ing the images in the soft copy environment allows for ated in any plane or using a curved surface to reduce panning, zooming, windowing, and leveling so that the distortion. Other advantages include increased speed viewing experience and diagnostic yield are optimal. and increased total volume coverage. Therefore, a single There are certain tradeoffs; the spatial resolution of dig- pass whole body protocol may be feasible, particularly ital radiography systems is not as great as that with film with 16-detector scanners that can image from the head screen radiography. However, as additional experience vertex to below the hips in less than 1 minute. The abil- and data are accumulated, it has been found that the im- ity to acquire high-quality images in the presence of proved contrast resolution is more important than spatial hardware/joint implants has improved using multislice resolution for diagnostic efficacy, making less defined spa- CT. Metal artifacts are caused by photopenic defects in tial resolution a reasonable trade-off (Figure 1). the back projection and are displayed on CT images as streak artifact. With multislice CT, the holes in the fil- Computed Tomography tered back projection are not as pronounced, resulting in a less severe streak artifact. This improvement is at The latest generation of CT scanners uses multiple de- the expense of excess tissue radiation along the penum- tector row arrays. Multislice CT represents a major im- bra of the beam, which is then picked up by adjacent provement in helical CT technology, wherein simulta- detector channels filling in these photopenic defects in neous activation of multiple detector rows positioned the projection. This technology has forced radiologists along the longitudinal or z-axis (direction of table or into redefining the image viewing process to a volumet- gantry) allows acquisition of interweaving helical sec- ric paradigm rather than a simple tile mode or section- tions. The principal difference between multislice CT by-section viewing. In addition, CT protocols have to be and predecessor generations of CT is the improved res- reformulated. There is also an expanded range of CT olution in the z-axis. More of the photons generated by applications and indications. The challenges associated the x-ray tube are ultimately used to produce imaging with multislice CT include selection of optimal imaging data. With this design, section thickness is determined sequences, controlling radiation exposure to the patient, by detector size and not by the collimator itself. Rapid data acquisition times are possible because of short gan- American Academy of Orthopaedic Surgeons 119

Musculoskeletal Imaging Orthopaedic Knowledge Update 8 Figure 1 Digital radiography and multi- slice CT multiplanar reformat image qual- ity. A, Anteroposterior projection of the knee performed with a direct radiography unit shows high-quality contrast. B, Mul- tidetector CT coronal multiplanar reformat image shows exquisite trabecular detail similar to conventional radiography. Source images were acquired using isotro- pic 0.75-mm voxels. Figure 2 Position compensated multiplanar reformat. Cervical spine multislice CT myelography in a patient who underwent anterior cervical fusion: Sagittal and coronal multiplanar reformat images are created from an axial image (A) while adjusting the planes to cor- rect for any rotation (double oblique prescriptions). Similar maneuvers are done for the sagittal (B) and coronal (C) planes to generate more useful sections based on true anatomic landmarks. Oblique axial im- ages (D) are also used to generate sagittal oblique im- ages (E) through the neural foramen at each level on each side to compensate for changes in orientation of the neural canal. Coronal and sagittal oblique multi- planar reformat images show an osseous ridge com- pressing the nerve roots (arrow in C and E). and efficiently managing the large amount of data gen- tons per voxels; because smaller voxels tend to have erated. Some disadvantages of multislice CT are high fewer photons, increased image noise is the result. To radiation dose to the tissue and potentially noisy im- keep the noise level reasonable, the exposure (and thus ages. Noise is inversely related to the number of pho- radiation dose) must be increased. 120 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 11 Musculoskeletal Imaging Ultrasound implications for oncology, especially for soft-tissue neo- plasms or postoperative cancer patients. PET has only Ultrasound is the medical imaging modality used to ac- recently been widely used in clinical oncology. Short- quire and display the acoustic properties of tissues. A lived positron emitting radioisotopes annihilate to form transducer array (transmitter and receiver of ultrasound two photons with trajectories approximately 180° apart pulses) sends sound waves into the patient and receives at a particular energy level (511 kev). The coincidental returning echoes that are converted into an image. Sound detection of these photons by a ring detector is recon- is mechanical energy that propagates through continuous, structed via a filtered backprojection (similar to CT) to elastic medium by the compression and rarefaction of the form images of tracer distribution. [18F] 2-deoxy-2- “particles” that compose it (such as air). The resolution of fluoro-D-glucose (FDG) is a metabolic tracer most the ultrasound image and attenuation of the ultrasound widely used in clinical PET oncology. FDG accumula- beam depend on the wavelength and frequency.A low fre- tion reflects the rate of glucose utilization in a tissue be- quency ultrasound beam has a longer wavelength and less cause FDG is transported into a tissue by the same resolution but greater depth of penetration. For muscu- mechanisms of glucose transport and trapped in a tissue loskeletal imaging of more superficial structures such as as FDG-6-phosphate, which is a poor substrate for the tendons and ligaments, a high frequency beam having a further enzyme systems of glycolysis or glycogen stor- smaller wavelength provides superior spatial resolution age. The use of FDG in evaluation of the musculoskele- and image detail. Thus, the creation of appropriate trans- tal system is based on increased glycolytic rate in patho- ducers is of critical importance in performing musculo- logic tissues. Thus, PET has proved to be the gold skeletal imaging. Higher frequency transducers ranging standard in metabolic imaging. FDG provides a means from 7.5 MHz up to even 15 MHz are now available. Mod- of quantitating the glucose metabolism, with the amount ern ultrasound scanners use phased array transducers with of tracer accumulation reflecting the glucose metabo- multiple piezoelectric elements to electronically sweep an lism. High-grade malignancies tend to have higher rates ultrasound beam across the volume of interest, thus being of glycolysis than do low-grade malignancies and benign able to create a three-dimensional image. lesions; therefore, high-grade malignancies have greater uptake of FDG than that of low-grade or benign lesions. Applications of ultrasound include evaluation of ten- don and muscle abnormalities such as rotator cuff tears. PET, as a metabolic imaging technique, has advan- In addition, ultrasound has also been applied to evaluate tages over and complements structural imaging methods the glenoid labrum and knee menisci. High-resolution ul- and also shows differences from conventional nuclear trasound has the potential to be used for visualization of medicine. All of these factors have led to its growth in articular cartilage. Synovial effusions and proliferation clinical applications in recent years. PET applications can be evaluated using color Doppler imaging to deter- are evolving, but the technique has been approved for mine the degree of hypertrophy and inflammation. Ultra- the diagnosis, staging, and restaging of many common sound has been used more often for diagnostic and ther- malignancies and has shown efficacy for the detection of apeutic procedures because of improved transducer osseous metastasis from several malignancies, including technology being better able to detect infrastructural de- lung and breast carcinomas and lymphoma. However, tail. In addition, ultrasound is a more economical modal- the significance of FDG PET in the evaluation of pri- ity for assessing a specific clinical concern. Ultrasound is mary bone tumors and tumor-like lesions has not been best used when the clinical question is specific and well extensively elucidated. Several investigators have re- formulated; the condition is dichotomous (is there a full ported the usefulness of FDG-PET in oncologic applica- thickness tear or not?); for characterizing a soft-tissue le- tions for primary musculoskeletal tumors. Preliminary sion (cystic or vascular); or for guiding particular interven- reports suggest a good correlation between glucose con- tions. Performing percutaneous interventions with ultra- sumption measured by FDG PET and the aggressive- sound ensures accurate needle tip placement and helps ness of musculoskeletal tumors. However, a significant direct the needle away from other regional soft-tissue overlap exists between benign and malignant groups; structures and neurovascular bundles.The visualization of therefore, PET is not a solo method for differential di- the needle tip in real time allows for reliable placement in agnosis of benign and malignant bone lesions. Both neo- the tendon sheath, bursa, or joint of interest. Intratendi- plastic and inflammatory processes can cause an in- nous calcifications, the plantar fascia, and interdigital crease in FDG activity; therefore, tissue sampling should (Morton’s) neuromas can also be visualized and injected be directed to the most metabolically active regions directly under real-time guidance. identified by PET (Figure 3). Therefore, PET has a role as a useful adjunct to anatomic imaging techniques be- Nuclear Medicine and Positron Emission Tomography cause it can provide an in vivo method for quantifying functional metabolism in normal and diseased tissues. The most significant recent advancement in nuclear medicine is positron emission tomography (PET) and the combination of PET CT scanners with important American Academy of Orthopaedic Surgeons 121

Musculoskeletal Imaging Orthopaedic Knowledge Update 8 Figure 3 PET CT coregistration image fusion. The imaging studies are from a patient who was referred for evaluation for metastatic bone disease. Composite image: Coronal and sagittal maximum intensity projection FDG-PET images (A and B) show an area with abnormal FDG uptake in the pelvis that is not localized with certainty. Coronal, sagittal, and transaxial PET-CT fused images (C, D, and E) reveal a hy- permetabolic focus corresponding to an os- teolytic lesion, which was confirmed histo- pathologically by percutaneous biopsy to be adenocarcinoma. Magnetic Resonance Imaging oxygen-16, oxygen-17, fluorine-19, sodium-23, and phosphorus-31, will help in providing and interpreting Recent MRI technology developments include high these images. Most clinical MRI is hydrogen imaging; field strength clinical systems for the entire body (3.0 more recently, sodium and phosphorus images have Tesla) and dedicated extremity scanners operating at 1.0 been obtained in vivo. Sodium imaging can be used for Tesla, with improved gradients and radiofrequency (RF) estimating the glycosaminoglycan content of articular coils. Parallel imaging and faster novel pulse sequences cartilage. Because of the low natural abundance of so- are addressing the time factor involved in obtaining an dium in articular tissues, in vivo imaging is limited to MRI scan. High spatial resolution imaging with im- high-field magnets (3.0 Tesla or greater). There are sev- proved signal-to-noise ratio has generated a new area of eral pulse sequences that have been applied to cartilage imaging known as magnetic resonance microscopy, used imaging. Gradient-recall echo imaging has been used for the smaller and more complex articulations such as because of its three-dimensional capability and ability to the hand, wrist, foot, ankle, and elbow. Expanding the provide high-resolution images. Fat-suppressed tech- types of three-dimensional pulse sequences available us- niques are combined with gradient-recall echo imaging ing fast spin-echo techniques afford the opportunity for to increase the dynamic range and improve the detec- isotropic voxel acquisition and better volumetric data tion of signal abnormalities in cartilage. However, scan rendering. Examination time can be reduced by using a acquisition time can be substantial (8 to 10 minutes), single acquisition and reconstructing the plane of inter- thus making the image prone to motion artifact. Magne- est (similar to multislice CT). Currently the most useful tization transfer contrast creates tissue contrast by the sequences are two-dimensional. Because musculoskele- exchange of magnetization between protons associated tal imaging often relies on the depiction of particular with macromolecules and bulk water protons by means anatomy, several planes are acquired using the same of cross relaxation or chemical exchange. Magnetization pulse sequence depending on the articulation, indica- transfer contrast acts as an off-resonant saturation pulse tion, and specific structure of interest. and may make cartilage lesions easier to see. Although this type of contrast is usually used in conjunction with Imaging of cartilage has been difficult; however, the gradient echo techniques, some magnetization trans- some new advances in MRI techniques, such as the use of biologically relevant elements such as hydrogen, 122 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 11 Musculoskeletal Imaging fer occurs inherently with fast spin-echo or turbo spin- seen in MRI. T2 is fairly constant at different field echo techniques. The driven equilibrium Fourier trans- strengths, but T1 increases with increasing field strength. form contrast method is another promising approach for Fat suppression is improved at 3T because the peaks be- imaging of cartilage disorders. This method produces tween water and fat are further separated (greater image contrast that is a function of proton density, chemical shift effect; the nature of the chemical shift T1/T2 and echo time/repetition time (TE/TR). Many tis- phenomenon is that protons associated with long chain sues have competing T1 and T2 contrast, so the T1 to T2 aliphatic fat molecules have precessional frequencies ratio for driven equilibrium Fourier transform contrast slightly lower than protons associated with mobile water tends to be synergistic. Driven equilibrium Fourier molecules, which is field strength-dependent), providing transform contrast is well suited to imaging articular more robust spectral fat suppression. The US Food and cartilage because synovial fluid is high and articular car- Drug Administration and manufacturers have mandated tilage is intermediate in signal intensity; the osseous the use of power monitoring systems for 3T because of structures are dark and lipids can be suppressed using increased danger of RF burns. The more problematic se- spectral fat saturation techniques. This creates an image quences are fast spin-echo/turbo spin-echo (unless the in which cartilage is easily distinguishable from all adja- refocusing pulse is reduced to less than 180°) and short cent tissues based on signal intensity alone, aiding seg- TR spin-echo sequences (T1-weighted). Motion artifacts mentation and volume calculation. appear worse at 3T and may be because of the overall higher signal to noise ratio. Susceptibility artifacts will Magnetic resonance arthrography has also been ap- be increased, and postoperative imaging may be more plied to the evaluation of cartilage and may be per- problematic at higher field strengths. Increasing the re- formed directly (a dilute gadolinium-containing solution ceiver bandwidth may also help alleviate these artifacts. is percutaneously placed into the joint via a needle) or There are improvements in speed because the signal to indirectly (intravenous gadolinium is administered and noise ratio is proportional to the square of the imaging allowed to diffuse into the joint). Gadolinium-enhanced time, and therefore it is possible to go up to four times imaging has the potential to monitor glycosaminoglycan faster at 3T than 1.5T while maintaining an equal signal (GAG) content within the cartilage. GAGs are funda- to noise ratio. mentally important for several reasons: they play a ma- jor mechanical support role, they are lost early in the Another trend is the use of dedicated extremity course of cartilage degeneration, and may need to be re- scanners that typically operate at low field to midfield plenished during the course of any effective cartilage ranges. Low field open scanners or extremity scanners treatment regimen. GAGs contribute strong negative have been available for several years. However, recently charge to the cartilage matrix and mobile ions will dis- a higher field extremity scanner at 1.0 T has become tribute to reflect local GAG concentration. When available (Orthone, ONI, Inc, Wilmington, MA). This GAGs are lost as part of the degenerative process, the unit can image the elbow, hand, wrist, knee, foot, and an- negative charge conferred to the cartilage also is lost. kle but cannot acquire images of the shoulder, hip, or Consequently, when a negatively charged contrast agent spine. Therefore, it is not considered a stand-alone unit is administered (either intravenously or intra- but may be useful for a high volume site with a backlog articularly) it preferentially distributes into the de- of musculoskeletal patients to supplement a whole body graded cartilage and the T1 effect of this contrast mate- unit. The site requirements are less than those for a con- rial can be qualitatively visualized and quantitatively ventional high field strength system, making it a more measured. With direct magnetic resonance arthrography, economical option. The image quality is much improved it takes 3 hours for the contrast to sufficiently diffuse over the typical low field open MRI or very low field into the cartilage, whereas with indirect magnetic reso- extremity scanners, and this type of device will likely nance arthrography it only takes approximately 1.5 have a niche role providing high-quality clinical images hours. for the amenable body parts (Figure 4). It is also a use- ful option for claustrophobic patients. There are Larger Clinical higher field MRI systems, typically 3.0 Tesla and smaller diameter RF coils available. Both coils are (or 3T) are becoming widely available. The higher in- quadrature types of volume transmit-receive coils, which trinsic signal-to-noise ratio of high-field strength MRI contribute to the improved image quality. There are cer- can be used to improve imaging speed or resolution but tain advantages when this method is compared with tra- changes in relaxation time at 3T as well as increased ar- ditional high field closed MRI systems. The images are tifacts must be considered. Nevertheless, 3T MRI offers of high quality despite the fact that the field strength is the opportunity to explore physiologic imaging of joints lower. Loss of signal to noise ratio and artifacts from off as well as morphologic features. Tissues in a magnetic isocenter imaging are minimized. The majority of pulse field are categorized by two types of relaxation: T1 sequences are available, including spectral fat suppres- (spin-lattice relaxation time) and T2 (spin-spin relax- sion. ation time). Manipulation of imaging parameters of the TE and the TR produce the various types of contrast American Academy of Orthopaedic Surgeons 123

Musculoskeletal Imaging Orthopaedic Knowledge Update 8 Figure 4 High-field open dedicated extremity MRI system. Elbow common extensor tendinopathy and partial tear: axial T1-weighted image (A) shows intermediate signal at the common extensor tendon ulnar attachment (arrowhead), coronal oblique T2-weighted image (B) with spectral fat suppression shows a small fluid gap (arrow) but not complete discontinuity of the common extensor tendon ulnar attachment reflecting a partial tear. Achilles tendinopathy (insertional tendinitis): axial T1-weighted image (C) through distal Achilles tendon (subjacent to marker) shows tendinosis manifested by enlargement (loss of the normal comma shape) and intermediate signal, sagittal T2-weighted image with spectral fat suppression. (Images courtesy of Barbara N. Weissman, MD and Rosemary J. Klecker, MD, Harvard Medical School, Brigham and Women’s Hospital.) Parallel imaging is a relatively new class of tech- In terms of improving communications between pro- niques capable of significantly increasing the speed of viders there is a multispecialty, multisociety-endorsed no- MRI acquisitions. Although a variety of different tech- menclature for the lumbar spine disk disease (some ad- niques have emerged, the common principle is to use vocate that this system may be used for cervical and the spatial information inherent in the elements of an thoracic spine descriptors also). It is important to recog- RF coil array to allow a reduction in the number of nize that the definitions of diagnoses should not define or time-consuming phase-encode steps required during the imply external etiologic events such as trauma, should not scan. Recent technical advances and increased availabil- imply relationship to symptoms and do imply need for ity to imaging centers place parallel imaging on the specific treatment. Hence, the following are pathoana- verge of widespread clinical use. tomic descriptors that do not imply a specific pathoetiol- ogy or syndrome. Osteoarthritis or osteoarthrosis is a pro- Imaging of Specific Orthopaedic Conditions cess of synovial joints. Therefore, in the spine it is appropriately applied to the zygoapophyseal (Z-joint, Spine facet), atlantoaxial, costovertebral, and sacroiliac joints. Degenerative disk disease is a term applied specifically to Disk Disease Nomenclature intervertebral disk degeneration. The term spondylosis is Spine imaging can exquisitely provide information re- often used in general as synonymous with degeneration, garding pathoanatomy of degenerative disk disease but which would include both nucleus pulposus and anulus fi- does not define a specific painful clinical syndrome be- brosus processes, but such usage is confusing, so it is best cause of the nonspecific appearance of painful versus that “degeneration” be the general term and spondylosis painless degenerative conditions. However, abnormal deformans a specifically defined subclassification of de- imaging findings of the lumbar disks may be degenera- generation characterized by marginal osteophytosis with- tive, adaptive, genetic, or a combination of environmen- out substantial disk height loss (reflecting predominantly tal and determined factors. Many findings may simply anulus fibrosis disease). Intervertebral osteochondrosis is represent senescent changes that are the natural conse- the term applied to the condition of mainly nucleus pul- quences of stress applied during the course of a lifetime. posus and the vertebral body end-plates disease including The imaging appearance of lumbar spine degenerative annular fissuring (tearing). disk disease has a similar incidence in symptomatic and asymptomatic patients. Therefore, the appropriate use of Normally, the posterior disk margin tends to be con- imaging modalities within a defined clinical context is cave in the upper lumbosacral spine (Figure 5, A), and is paramount. For some patients with complicated or re- straight or slightly convex at L4-5 and L5-S1. The poste- calcitrant symptoms, the most useful aspect for ad- rior margin typically projects no more than 1 mm be- vanced imaging techniques may be in the exclusion of yond the end plate. An annular bulge is described as a more serious causes of axial low back pain such as infec- generalized displacement (greater than 180°) of disk tion, neoplasm, or fracture rather than the inclusion of margin beyond the normal margin of the intervertebral any specific degenerative findings. 124 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 11 Musculoskeletal Imaging Figure 5 Lumbar disk contour abnormalities; all are axial T2-weighted images at the level of the intervertebral disk. A, Normal: the posterior disk margin (arrowhead) should have a slight concavity, with the exception of the lumbosacral junction, which may have a slight convexity. B, Annular bulge: There is generalized displacement (arrowheads) of greater than 180° of the disk margin beyond the normal margin of the intervertebral disk space and is the result of disk degeneration with an intact anulus fibrosus. C, Disk protrusion: The base against the parent disk margin is broader than any other diameter of the herniation. Extension of nucleus pulposus through a partial defect in the anulus fibrosus is identified (arrow) but the herniated disk is contained by some intact annular fibers. D, Disk extrusion: The base against the parent disk margin is narrower than any other diameter of the herniation (arrowhead). There may be extension of the nucleus pulposus through a complete focal defect in the anulus fibrosus. Substantial mass effect is present, causing moderate central canal and severe left lateral recess stenosis. disk (Figure 5, B). The normal margin is defined by the than 90° circumference). Extrusion refers to a herniated vertebral body ring apophysis exclusive of osteophytes. disk in which, in at least one plane, any one distance be- The annular bulge can be the result of disk degenera- tween the edges of the disk material beyond the disk tion with a grossly intact anulus. Disk margins tend to space is greater than the distance between the edges of be smooth, symmetric, or eccentric and nonfocal, and the base in the same plane (Figure 5, D), or when no may have a level-specific appearance in the lumbar continuity exists between the disk material beyond the spine. Disk herniation is a localized displacement (less disk space and that within the disk space. An extrusion than 180° of the circumference) of disk material beyond is characterized by the following: the base against the the normal margin of the intervertebral disk space (Fig- parent disk margin tends to be narrower than any other ure 5, C). This material may consist of nucleus pulposus, diameter of the herniation; extension of the nucleus pul- cartilage, fragmented apophyseal bone, or fragmented posus through a complete focal defect in the anulus fi- annular tissue. It is often the result of disk degeneration brosus. Extruded disks in which all continuity with the with some degree of focal annular disruption. The types disk of origin is lost may be further characterized as se- of disk herniation are designated as protrusion, extru- questrated. Disk material displaced away from the site sion, and free fragment (sequestration). Protrusion re- of extrusion may be characterized as migrated; it may fers to a herniated disk in which the greatest distance in stay subligamentous, contained by the posterior longitu- any plane between the edges of the disk material be- dinal ligament or may migrate widely. Schmorl’s nodes yond the disk space is less than the distance between are intervertebral disk herniations (transosseous disk the edges of the base in the same plane. It is character- extrusion). Herniation of the nucleus pulposus occurs ized by the following: the base against the parent disk through the cartilaginous end plate into the vertebral margin is broader than any other diameter of the herni- body. These herniations often have a characteristic ation; extension of nucleus pulposus may occur through round or lobulated appearance. They may enhance after a partial defect in the anulus fibrosus but is contained contrast administration with ring-like enhancement be- by some intact outer annular fibers and the posterior ing most common. They are often incidental and likely longitudinal ligament. The types of protrusions may be to be developmental or posttraumatic rather than broad based (90° to 180° circumference) or focal (less purely degenerative or adaptive. There is now imaging American Academy of Orthopaedic Surgeons 125

Musculoskeletal Imaging Orthopaedic Knowledge Update 8 evidence of a significant genetic association between the weight-bearing paradigm becomes validated, then the COL9A3 tryptophan allele (Trp3 allele), Scheuermann’s currently installed base of magnets can be used without disease, and intervertebral disk degeneration among having to deploy new, costly space-occupying devices. symptomatic patients. Further studies comparing simulated weight-bearing versus upright imaging will be needed to show whether There are no formal staging systems for lumbar degen- new magnets are required for this purpose. erative disk disease and most physicians will commonly report findings using the designations of mild, moderate, Sports Medicine: Magnetic Resonance Arthrography and severe disease. However, these designations will hold different meaning among physicians, especially with re- For any joint the placement of intra-articular contrast spect to degree of disk degeneration. The following whether by direct or indirect means can be used to as- scheme is used to define the degree of canal compromise sist the evaluation of ligaments, cartilage, synovial pro- produced by disk displacement based on the goals of be- liferation, or intra-articular loose bodies. MRI provides ing practical, objective, reasonably precise, and clinically cross-sectional and multiplanar imaging for precise spa- relevant. Measurements are typically taken from an axial tial delineation and an additional capability to supply section at the site of the most severe compromise. Canal soft-tissue contrast outside of the joint cavity (tendons, compromise of less than one third of the canal at that sec- muscles, and bone marrow) unavailable by any other tion is mild, between one and two thirds is moderate, and modalities. Pertinent issues for optimizing diagnostic over two thirds represents severe disease. This scheme yield include technical considerations in performing may also be applied to foraminal (neural canal) narrow- magnetic resonance examinations, properly identifying ing with the sagittal images also playing a useful role for structures of interest, and the clinical significance of the defining the degree of narrowing. Observer interpreta- incidental findings. Magnetic resonance arthrography tions are also made with various degrees of confidence. has been most extensively studied in the shoulder and Statement of the degree of confidence is an important to a lesser degree in the hip and the postoperative knee. component of communication. The interpretation should Other joints in which it has been applied include the el- be characterized as “definite” if there is no doubt, “prob- bow and wrist and to a lesser degree the ankle. able” if there is some doubt but the likelihood is greater than 50%, and “possible” if there is reason to consider but Direct magnetic resonance arthrography, most often the likelihood is less than 50%. done with injection of diluted gadolinium or less often with saline solution, can be useful for evaluating certain Positional, Load-Bearing, and Dynamic pathologic conditions in the joints. Gadolinium-based (Functional) Imaging contrast agents have not been approved by the US Food Because imaging in the supine position may not fully re- and Drug Administration for intra-articular injection veal the anatomic lesions, there has been an interest in but may be used clinically under the doctrine of the performing functioning, positional, or load-bearing im- practice of medicine. These agents are most helpful for aging of the spine. Spine imaging position options avail- outlining labral-ligamentous abnormalities in the shoul- able are supine, supine with axial loading (simulated der (Figure 6) and distinguishing partial-thickness from weight bearing), seated, or standing upright position. full-thickness tears in the rotator cuff, demonstrating la- Noncompressive lesions on conventional MRI may bral tears in the hip, showing partial- and full-thickness show encroachment and neural element impingement tears of the collateral ligament of the elbow and delin- on dynamic load-bearing (seated) scans. Fluctuating po- eating bands in the elbow, identifying residual or recur- sitional foraminal and central spinal canal stenosis has rent tears in the knee after meniscectomy (Figure 7), in- also been shown in the cervical spine between recum- creasing the certainty of perforations of the ligaments bent and upright neutral position. This situation has led and triangular fibrocartilage in the wrist, correctly iden- to a concept of fluctuating kinetic central spinal canal tifying ligament tears in the ankle and increasing the stenosis (fluctuating fluid disk herniation) that can only sensitivity for ankle impingement syndromes, assessing be shown with these different positions. Cervical spine the stability of osteochondral lesions in the articular sur- imaging in the recumbent position showing posterior os- face of joints, and delineating loose bodies in joints. Di- teophytes may only reveal cord compression with rect magnetic resonance arthrography has become a upright-extension positioning. Because of the preva- well-established method of delineating various joint lence of back pain that occurs in a nonsupine position structures that otherwise show poor contrast on conven- and the inability of routine supine MRI to satisfactorily tional MRI. However, direct magnetic resonance ar- reveal clinical syndromes, it is likely that positional im- thrography is minimally invasive and usually necessi- aging will have a role in the future but how it exactly tates fluoroscopic guidance for joint injection (some will be implemented is as yet undetermined; the role of authors have described doing blind injections or using imaging the hip, knee, and ankle under axial load also other modalities such as ultrasound or MRI). warrants further investigation. If the supine simulated 126 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 11 Musculoskeletal Imaging Figure 6 Direct magnetic resonance arthrography of the shoulder. T1-weighted fat-suppressed images obtained after the intra-articular injection of a dilute gadolinium solution. A, Buford complex: axial image at the level of the coracoid process shows a deficient anterosuperior labrum (white arrow) with a thick cord-like middle glenohumeral ligament (black arrowhead) reflecting a normal developmental variant. B, Bankart lesion: axial image caudal to the level of the coracoid process shows contrast intravasation into an irregular deformed anteroinferior glenoid labrum (arrow) distinct from the middle glenohumeral ligament (arrowhead). C, Superior labral anterior and posterior lesion: coronal oblique image posterior to the biceps attachment to the glenoid shows an irregular collection of contrast material (arrow) extending into the superior labrum with partial detachment. Intravenous gadolinium-based contrast leaks from Figure 7 Direct magnetic resonance the capillary bed into the interstitial space of the syn- arthrography of the knee: Sagittal T1- ovium and then diffuses through the synovial lining into weighted fat-suppressed spin echo the joint cavity. Because the synovial membrane is images show a horizontal increased highly vascular, intravenous gadolinium-based contrast intrameniscal signal intensity similar material enhances the joint cavity, causing the arthro- to the contrast material extending to graphic effect. This technique has developed as an alter- the free margin (arrow) of the poste- native to direct magnetic resonance arthrography for rior horn of the medial meniscus, re- imaging joints. The arthrographic effect is dependent on flecting a recurrent meniscal tear. The the degree of synovial enhancement and volume of syn- posterior horn of the medial meniscus ovial fluid. Synovial enhancement is poorer in nonin- is truncated from a prior partial me- flamed joints. Well-vascularized and inflamed tissues niscectomy. Extensive cartilage loss of will show enhancement with this method. One limita- the posterior aspect of the lateral tion of indirect magnetic resonance arthrography is a femoral condyle is seen. lack of controlled joint distension compared with that of direct arthrography. Joint distension facilitates recogni- perfusion but also increases vascular pressure. Exercise tion of certain conditions such as capsular trauma or also leads to motion within the joint fluid, thereby re- soft-tissue injury concealed by a collapsed capsule. ducing the concentration of contrast adjacent to the syn- Joints with a large capacity (knee, hip, shoulder) are less ovial membrane and thus facilitating the diffusional ef- suited to indirect magnetic resonance arthrography be- fect. Increase in signal intensity of joint fluid has been cause the larger volume necessitates a longer delay and reported to be four times greater in joints that were ex- leads to less predictable heterogeneous enhancement. ercised 10° up to 15 minutes before imaging compared Nonetheless, indirect magnetic resonance arthrography with joints that were not exercised. Without exercise the can provide diagnostic arthrogram-like images of the signal intensity increases slowly and reaches a maximum shoulder, elbow, wrist, hip, knee, and ankle joint if the after approximately 60 minutes. In patients with os- technique is optimized. Fat saturation and joint exercise teoarthritis, maximum enhancement may occur as late before imaging is critical to provide high signal intensity as 90 minutes in the absence of joint motion. As con- joint fluid. Diffusion is increased in joints, which are in- trast diffusion is based on the concentration difference flamed, or after gentle exercise, because of physiologic between plasma and joint fluid, increasing the dose of hyperemia. Factors affecting passage of contrast mate- contrast material administered intravenously may in- rial between the blood vessels and synovial fluid include crease the diffusion gradient. However, double- and pressure differences between these spaces and the vis- triple-dose intravenous injections have been shown to cosity of the intra-articular fluid. The normal joint space have a limited positive effect on indirect arthrography. is a low-pressure space, containing joint fluid of rela- tively low viscosity. Exercise not only increases vascular American Academy of Orthopaedic Surgeons 127

Musculoskeletal Imaging Orthopaedic Knowledge Update 8 Figure 8 Indirect magnetic resonance arthrography of the wrist: lunotriquetral liga- can detract from quality because of artifacts related to ment tear. Coronal T1-weighted fat suppressed spoiled gradient recalled image ob- reduced field homogeneity. Using a high-field dedicated tained after the administration of a standard dose of intravenous gadolinium based extremity magnet can improve overall quality by having contrast material and 10 minutes of exercise shows high signal equal to contrast ma- the structure of interest within the isocenter. High- terial in the lunotriquetral interval (arrow) reflecting ligament disruption (normally quality surface RF coils should be used for wrist or el- there should be a low signal band at the base of the proximal carpal bones). Note the bow imaging and can improve the signal-to-noise ratios multicompartment enhancement. threefold to fivefold. Higher field strength with stronger gradients (increased slew rates) allows for thinner sec- Thus, a standard dose of gadolinium-based contrast in- tion acquisition, smaller field of views, and reduced jected intravenously is usually sufficient to attain a good scanner time. Conventional MRI systems have a 3-mm signal to noise ratio and good contrast to noise ratio. It section limitation for two-dimensional pulse sequences allows simultaneous assessment of both intra-articular because the amplifier can only deliver a fixed amount of and extra-articular soft tissues but the physician must be power to the gradient coil. The addition of volumetric cognizant of the determinants of contrast enhancement three-dimensional imaging can also be useful. The elbow not to be confounded by normally enhancing structures and wrist are joints that contain compact anatomy and (Figure 8). Indirect magnetic resonance arthrography is perform complex motions. Frequently, the structures of a useful adjunct to conventional musculoskeletal MRI, interest are not well shown in the standard planes of im- may be preferable to the more invasive direct magnetic aging and appropriate positioning at optimal planes resonance arthrogram in certain applications, and often needs to be acquired for each area. A three-dimensional can be performed when direct arthrography is inconve- pulse sequence that can be dynamically manipulated nient or not logistically feasible (outpatient magnet). Al- may be advantageous in this context. Contrast resolu- though indirect magnetic resonance arthrography has tion issues are also extremely important and are related some disadvantages, it does not require fluoroscopic to determining the optimal pulse sequence. For certain guidance or joint injection and it is often superior to structures in the wrist and elbow such as the fibrocarti- conventional MRI in delineating structures. lage, ligaments, and capsule, there is a limited inherent contrast that normally exists. In this respect intra- Hand/Upper Extremity: Internal Derangements articular contrast medium (magnetic resonance arthrog- of the Wrist raphy) greatly assists the conspicuity of findings. The contrast-to-noise ratio tends to improve by fat suppres- Challenges associated with MRI of the hand and upper sion because this alters the dynamic range by reducing extremity are related to the small compact complex the contribution of signal from fat with the smaller con- anatomy and the high special resolution requirement. trast differences rescaled across a broader range of sig- High signal-to-noise ratios are desired; however, thin nal intensity pixel values. The resulting effect is that the section, small field of view, and high-resolution images rescaling provides amplified contrast even with nonfat- all detract from signal-to-noise ratios. Off isocenter im- containing structures (such as cartilage). Currently, gra- aging, as is commonly done for the elbow and the wrist, dient echo sequences can provide high-resolution imag- ing but there are significant contrast limitations. Spurious signals are often present in tendons and liga- ments, particularly when they approach a 55° angle to the main magnetic field (causing magic angle artifact, a T2 shortening phenomenon manifested in short TE im- ages). This is often the case in at least some portion(s) of some of the tendons given the complex anatomy in this region. MRI of the hand, wrist, and elbow is useful for extra-articular pathology and in this sense is comple- mentary to diagnostic arthroscopy. The reports for diag- nostic performance of MRI for ligamentous wrist le- sions in the literature are variable. Thus, MRI has not achieved a respected role in defining the biomechani- cally clinically significant lesions in the wrist. One mech- anism to improve spatial resolution is to use dedicated high-resolution coils. Thin and contiguous slices are needed for adequate MRI of the wrist because many of the larger ligaments around the wrist are no greater than 1 to 2 mm thick. Recent magnetic resonance tech- 128 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 11 Musculoskeletal Imaging nology allows the use of a microscopy coil, which pro- the signal intensity is directly proportional to the vides high-resolution MRI of the hand and wrist. High- amount of extracellular water. Contrast enhancement resolution MRI with a microscopy coil is a promising occurs in areas of BME irrespective of etiology (benign method to diagnose triangular fibrocartilage complex or malignant, infectious or noninflammatory). The po- and other ligament lesions. The limitation of microscopy tential etiologies of BME include diseases in the cate- coils is that the depiction of deep structures is inade- gory of trauma, biomechanical, developmental, vascular, quate. However, this may be resolved by combined posi- neoplastic, inflammatory, neuropathic, metabolic, degen- tioning with a larger surface coil or a flexible coil. In ad- erative, iatrogenic, and potentially idiopathic conditions dition, the limited sensitivity of microscopy coils may (transient BME syndromes). sometimes make accurate coil setting difficult over tar- geted structure or suspected lesions. The availability of Occult injuries result from an acute overt episode of superconducting coils has also been applied to small trauma. The physician should suspect a fracture in these joint imaging. Overall, it is likely that advanced coil de- patients. The traditional modality applied to fracture de- velopment will lead to improved diagnostic perfor- tection has been radiography, which may be negative or mance of MRI because high spatial resolution imaging indeterminate for nondisplaced fractures or a fracture is paramount to detect infrastructural features of the plane that is not tangential to the x-ray beam. In this wrist and elbow when evaluating for internal arrange- context MRI serves as a more sensitive technique for ments. fracture detection and characterization. Contusions, also known as bone bruises, are considered microtrabecular Foot and Ankle: Bone Marrow Edema-Like Lesions fractures. On MRI there is no fracture line and the pat- tern may be a clue or secondary sign of ligament or ten- Bone marrow edema (BME)-like lesions are often ob- don injury. These fractures often occur in a subarticular served on MRI. Although BME-like signal is not spe- location from osteochondral impaction injuries. cific on MRI, additional morphologic findings are often useful to reveal the etiology of many BME patterns. In terms of developmental conditions the normal Normal marrow constituents have three components: conversion of red marrow to yellow marrow sometimes osseous, myeloid elements, and adipose cells. Hemato- has areas of slight T2 or STIR hyperintensity but these poietic (red) marrow has approximately 40% fat con- usually are not as bright as pathologic lesions. Areas of tent and fatty (yellow) marrow has 80% fat content. The a developmental synchondrosis with failure of segmen- appendicular skeleton tends to have more fatty marrow tation of the primitive mesenchyme may cause symp- than hematopoietic marrow and this serves as a natural toms via abnormal biomechanics. Symptomatic fibrous contrast agent, showing bright T1 signal and suppression or cartilaginous tarsal coalitions often show reciprocal on fat saturation images. MRI to detect BME relies on areas of BME. Anatomic variants that can present as fluid-sensitive sequences (short-tau inversion recovery painful lesions may be considered a separate but related [STIR] and fat suppressed T2-weighted images). T1- category. Those of chronic chondro-osseous disruption weighted images can supplement T2-weighted images include bipartite patella, dorsal defect of the patella, and and are very specific for the infiltrative process, but are os subfibulare of the ankle. Those in the congenital syn- not as sensitive if there is nonfat marrow or no substan- chondrosis category include accessory navicular bone tial degree of edema. Gradient echo images are poor for and os trigonum. There are lesions that may predispose assessing marrow because of increased susceptibility re- to premature degenerative joint disease; one example is lated to the interfaces between the trabecula and he- the os intermetatarsarum, which can contribute to hal- matopoietic marrow. Gradient echo images can be use- lux valgus by causing excessive metatarsus varus. When ful to reveal other diagnoses such as lesions that contain these variants are symptomatic they often demonstrate iron, calcium, or hemosiderin (pigmented villonodular BME-like signal about the abnormality, reflecting al- synovitis). Other novel MRI techniques that have been tered biomechanics, chronic stress, or sometimes areas variably applied include chemical shift imaging, diffu- of osteonecrosis. It is thought that MRI can form an ob- sion weighted imaging, and magnetic resonance spec- jective basis for management of the lesions, particularly troscopy. when surgery is considered. BME lesions can reflect nonspecific response to in- The well-established vascular causes of BME-like jury or excess stress. The pathophysiology is related to signal may be related to either hyperemic or ischemic the extracellular fluid, which can be affected by hyper- conditions. Of the hyperemic etiologies, inflammatory vascularity and hyperperfusion (hyperemia), an inflam- disorders that increase vascularity or disuse may cause matory infiltrate causing resorption, granulation (fi- subarticular BME patterns. The disuse pattern is also brovascular) tissue or an adaptive/reactive phenomena partly related to increased blood flow, can be character- related to biomechanical alterations (MRI manifesta- istic and parallels the radiographic appearance of ag- tion of Wolff’s Law). The pathoetiologies are legion and gressive osteoporosis with diffuse or multiple rounded areas of fluid-like hyperintensity in a subarticular and metaphyseal distribution predominantly in the hindfoot American Academy of Orthopaedic Surgeons 129

Musculoskeletal Imaging Orthopaedic Knowledge Update 8 Figure 9 Osteomyelitis superimposed on neuropathic arthropathy. A, Axial T1-weighted spin-echo image of the midfoot reveals disorganization and dislocation of the Chopart joint, showing replacement of the normal marrow with diffuse infiltration of hypointense signal (arrowheads) in the tarsal bones. B, Sagittal T2-weighted fast spin-echo image reveals marrow edema in the midfoot and hindfoot bones, tarsus effusions, a rocker bottom deformity and fluid-like signal in the overlying subcutaneous tissues (arrow). C, Sagittal T1-weighted spin-echo contrast-enhanced image shows rim enhancement around plantar sinus tracts (small arrows) from the ulcer base and extending into midfoot reflecting a plantar space abscess (large arrow). The marrow edema is enhancing, which is nonspecific, but there is cortical irregularity of the anterior aspect of the cuboid adjacent to the soft-issue enhancement (arrowhead). The secondary signs of cutaneous ulcer, sinus tract, and cortical interruption have the highest positive predictive value for osteomyelitis. and midfoot. In terms of ischemic lesions, the broad cat- One notable exception is an ulceration that develops egory of osteonecrosis (infarct, osteonecrosis) can have because of poorly fitting footwear, or foot deformity BME early in the course of the disorder associated with and altered weight bearing that can cause atypical loca- acute, painful symptomatology. Pain improvement usu- tion of osteomyelitis. However, there should be a soft- ally parallels the resolution of the BME-like signal. The tissue defect identified over these areas to diagnose os- MRI pattern shows early BME with loss of subchondral teomyelitis. The epicenters of signal abnormalities can fat signal intensity. The double line sign is specific and be useful. Neuropathic disease has an articular epicenter most often identified as a ring of T1 hypointensity and and usually multiple joints are involved with a regional T2 hyperintensity. This likely reflects a reactive interface instability pattern. Osteomyelitis has a marrow epicen- rather than chemical shift artifact. MRI signal of the ne- ter with focal centripetal spread throughout the bone. It crotic segment may be reconstituted and appear fatty is important to emphasize that transcutaneous spread is because of the lipid content (the signal is not signifi- the route of inoculation in more than 90% of cases of cantly altered because of the reduced metabolic state). osteomyelitis of the foot in patients with diabetes. MRI findings may be seen as early as 10 to 15 days and Therefore, secondary soft-tissue signs are paramount; a for most patients within 30 days after the vascular in- subcutaneous ulcer with interruption of cutaneous sig- sult. Transient osteoporosis or the MRI correlate, tran- nal, cellulitis, soft-tissue mass effect from a phlegmon, sient bone marrow edema syndrome, may occur in nu- soft-tissue abscess (well-defined rim enhancing fluid col- merous other low extremity locations including the hip, lection) and particularly a sinus tract strongly support knee, talus, cuboid, navicular, and metatarsals. In addi- infection (Figure 9). tion, it may be migratory and occur in a ray pattern. Some believe that these lesions may reflect salvaged os- It has been recently recognized that degenerative teonecrosis but it is likely that many of these lesions conditions are associated with areas of BME. These de- may simply be biomechanical in nature. generative conditions may occur with either primary or secondary osteoarthritis. Geodes (subchondral cysts) In the inflammatory category it is well established are one of the imaging hallmarks of osteoarthritis and that infectious etiologies cause BME. One difficult dif- can be identified on MRI. Early during the course of ferential diagnosis in the setting of diabetic neuropathy disease, ill-defined areas of BME appear and later form is distinguishing osteomyelitis from a Charcot joint. discrete cystic structures. Some of these areas with hy- There are several MRI findings that may help in the dif- perintensity have been shown by pathologic studies not ferentiation. Osteomyelitis is more common in the pha- to reflect the fluid. It has been hypothesized that some langes, distal metatarsals, and calcaneus (secondary to of these findings are likely mechanical or adaptive re- overlying ulceration) whereas neuropathic disease is sponses related to the altered mechanics from the joint more common in the Lisfranc, Chopart, and ankle joints. failure and may be considered the MRI manifestation 130 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 11 Musculoskeletal Imaging Figure 10 Tendinopathy-associated bone marrow edema. A and B are T2-weighted fat- suppressed fast spin-echo MRI. Posterior tibi- alis tendon dysfunction: axial image (A) shows medial malleolus marrow edema (arrowhead) immediately subjacent to the posterior tibialis tendon (arrow). Peroneal tendinopathy: coro- nal image (B) shows peroneus longus tendon tenosynovitis (arrow) with underlying subtendi- nous bone marrow edema in peroneal tuber- cle of the calcaneus (arrowhead). of Wolff’s Law. In the knee (and possibly in the ankle neus (along the peroneal tubercle). Noninfectious in- and foot) bone marrow findings are strongly associated flammatory enthesopathies such as psoriatic or reactive with the presence of pain, and moderate or larger fu- arthritis cause prominent flame-shaped BME patterns sions in synovial thickening are more frequent among at the tendon-bone junction (enthesis) often with an as- those with pain than those without pain adjusted for de- sociated erosion that may be better appreciated with ra- gree of radiographic osteoarthritis. In addition, focal diography. subchondral BME may be a clue to focal cartilage de- fects (potential treatable cartilage defects), which pre- There are several miscellaneous but important causes sumably are posttraumatic events. The cartilage abnor- of lower extremity BME patterns. Hematopoietic (red) mality itself may be relatively inconspicuous on MRI marrow can sometimes be confused for an abnormal pulse sequence selection or spatial resolution and there- BME pattern. Hematopoietic marrow is most prominent fore an area of subarticular flame-shaped BME in a in the pediatric population and there is a conversion pat- nonarthritic joint can be a helpful secondary sign. An- tern progression from distal to proximal. One important other recently described pattern of BME is a subtendi- realization is that once an epiphysis is ossified, it should nous location. This has been identified as a response to contain fatty signal with a couple of important exceptions tendon abnormality and hypothesized to be from me- (reconversion not infrequently occurs in proximal femo- chanical friction, hyperemia, or because of biomechani- ral epiphysis). In general, reconversion related to anemia cal reasons. A subtendinous location is most common in or other conditions is in the opposite direction. In terms the lower extremity, particularly in the foot and ankle, of marrow replacement disorders (leukemia and lym- and is most often seen with posterior tibialis tendon phoma) the pattern may be a diffuse or focal area of mar- (PTT) dysfunction (Figure 10, A). The areas of edema row signal abnormality.With infiltrative diseases, the mar- related to PTT dysfunction are the medial tibia (malleo- row pattern tends to have some asymmetry and lus), navicular tubercle, calcaneous, and talus. This find- pathologic processes tend to have more T2 prolongation ing is not seen in most people with PTT dysfunction but and higher signal intensity (brighter BME). Neoplasms of- may be a sign for a more advanced stage and poorer ten show lesional or perilesional BME. The signal inten- tendon quality. Less frequently, BME may also be re- sities are unreliable for histology and there is substantial lated to peroneal tendinopathy (Figure 10, B): typically overlap between benign and malignant conditions. Met- in the lateral fibula (lateral malleolus) or lateral calca- astatic deposits are hematogenous in origin and are pre- dominantly located in red marrow areas (axial skeleton) American Academy of Orthopaedic Surgeons 131

Musculoskeletal Imaging Orthopaedic Knowledge Update 8 but can also be present in the appendicular skeleton, es- formed. Early MRI evaluation in children with lower pecially for deposits from bronchogenic or breast carci- extremity fractures can be prognostic. Physeal narrow- noma. For primary neoplasms, the degree of BME does ing or tethering in the absence of growth arrest lines not correspond to malignancy potential.There are several was found in those patients who subsequently required well-known benign lesions that are characterized by very late surgical intervention. The MRI in acute phase pro- prominent BME: chondroblastoma, osteoid osteoma, and vided accurate evaluation of physeal fracture anatomy Langerhans cell histiocytosis. Patients who have under- and could often augment the staging of the Salter-Harris gone radiotherapy or chemotherapy, those who are tak- classification. The course and level of injury within the ing bone marrow recovery agents, and patients who have cartilage physeal fracture-separation can be defined recently undergone débridement may show BME de- with MRI. Extension into the juxtaepiphyseal region is pending on the time course of the treatment. another potential risk factor for growth arrest and is de- tectable by MRI. Early MRI can demonstrate transphy- Pediatrics: Physeal Lesions and Growth Arrest seal bridging or altered arrest lines in physeal fracture before they become manifest on radiographs. Physeal The growing skeleton is susceptible to injury. Advances enhancement decreases with physeal closure as ex- in pediatric musculoskeletal radiology have been made pected. In the marrow and the extremities, contrast en- in imaging the cartilage, epiphysis, and physis. Closure hancement is greater in the metaphyseal metathesis por- disturbance of the long bones in children is frequently tion than the fatty epiphyseal portion. In both areas posttraumatic but also occurs because of physeal, epi- enhancement decreases as the marrow becomes more physeal, or metaphyseal ischemia. The growth mecha- fatty. Local physeal widening in a growing bone may nism represented by the cartilage structures at the ends represent the imprint of the previous or ongoing inter- of growing bones is not directly visible on radiography ference with endochondral ossification. Widening can be but is well visualized by MRI. Improved definition of seen on a fluid-sensitive pulse sequences in physeal dys- cartilaginous abnormality by MRI may permit earlier function without bridge formation. Physeal widening detection and treatment of disorders and thus prevent with focal palisading morphology, central distribution in bone deformity. The formation of physeal bars (bony the metaphysis and concomitant epiphyseal signal ab- bridges across the growth plate) is one active area of pe- normalities are significant predictors of subsequent diatric musculoskeletal radiology research. Premature growth disturbance. Therefore, MRI should be consid- bony fusion in children is most often posttraumatic and ered as part of the evaluation for patients at high risk disproportionately involves the tibia and femur with for growth disturbance, especially young children with bridges tending to develop as the site of earliest physio- extensive residual growth potential and those that in- logic closures (anteromedially and centrally). The distal volve particularly vulnerable growth plates (such as tibia, proximal femur, and proximal tibia physes are dis- about the knee) and pediatric patients with severe com- proportionally at risk because of the complex geometry. plex fractures. MRI is now a standard of care and helps The central undulations in the distal femur and Kump’s surgical management for these patient populations with bump in the distal tibia are sites of initial physiologic cartilage-sensitive sequences, exquisitely showing the closure and the most frequently involved in the prema- disturbance and associated abnormality that may follow ture fusions. Animal studies with physeal and metaphy- physeal injuries. seal injuries have shown MRI can identify persistence of abnormality in the growth cartilage after physeal inju- Orthopaedic Oncology: Metabolic Imaging ries and evolution of abnormalities after metaphyseal injury best seen on T2-weighted images. It has been Distinguishing benign from malignant soft-tissue lesions shown on MRI in animal models that abnormalities in in the extremities is a difficult if not impossible task by the physeal cartilage result in development of a trans- imaging using either signal, morphologic, or enhance- physeal vascularity that precedes the formation of bony ment criteria. Follow-up imaging for sarcoma patients is bridge after trauma. MRI can detect this transphyseal also complicated by complex prostheses, which can pro- vascular lesion within the first 2 weeks of injury. In vivo duce artifacts and limit visualization at the surgical site. studies in humans confirm that MRI defect abnormali- PET scanning, discussed earlier in the chapter, holds ties in the cartilage are associated with subsequent promise in showing metabolically active areas and may growth disturbances and provide accurate mapping of be particularly suitable for monitoring patients after physeal bridging and associated growth abnormality in therapy (resection, chemotherapy, or radiotherapy). the posttraumatic population (Salter-Harris injuries). Contrast enhancement can be useful in showing recon- Orthopaedic Traumatology: Multislice stitution of metaphyseal vascularity after injury but does not reliably enable the detection of transphyseal vascu- Computed Tomography larity after physeal injury until a distinct bony bridge is One of the most recently evident benefits of multislice CT is in the setting of appendicular and axial trauma. CT 132 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 11 Musculoskeletal Imaging greatly improves the anatomic depiction of spinal injury use of spinal injections should be considered a team ef- when compared with projectional radiography. Compared fort in conjunction with an experienced clinical diagnos- with single detector helical CT scanners, multislice CT tician who can accurately diagnose the patient’s prob- scanners have increased tube heating capacity and run at lem and recommend the appropriate procedure. a higher table speed, allowing an increased volume of cov- Performance of these procedures requires an intimate erage with the same amount of scanning time. This makes knowledge of relevant anatomy, appropriate equipment screening examination of part of the spine or the entire and facilities, and apprenticeship with an experienced spine feasible, which may eliminate screening radiographs practitioner. Selective epidural injections can offer sig- in certain settings. Examinations of the thorax and the nificant diagnostic and therapeutic benefit for patients lumbar spine can be extracted from a CT examination of with radicular pain. Attention to proper technique will the chest abdomen and pelvis. minimize risk of complications from these procedures while maximizing their benefit. There are several pitfalls to be aware of but the most important image artifacts are not unique to multislice CT. Controversy and differences in opinion related to These pitfalls include metal-induced streak artifact and epidural steroid injections often revolve around choice patient motion. Because of the higher spatial resolution, of trajectory (transforaminal versus transflaval [trans- vascular channels of the vertebral bodies are better appre- laminar, interlaminar]) and whether to use image guid- ciated and may be mistaken for normal structures. Mul- ance. Transflaval injections may be done with or without tislice CT has some risk predominantly related to the ra- image guidance (using loss of resistance techniques), diation dose to the individual patient and to the whereas transforaminal injections are done with image population. The radiation dose of the patient increases as guidance. Studies reviewing the efficacy of epidural ste- the volume of coverage increases. Multislice CT allows roid injections favor it as a useful treatment overall. imaging of very thin sections quickly, much faster than However, controlled clinical trials performed without previously possible, allowing for effective screening of spi- fluoroscopic guidance are not unanimous in demonstrat- nal injuries and evaluating extremity injuries. Screening ing the benefits of lumbar epidural steroid injections CT of the entire cervical spine is cost effective if high-risk with a broad range of successful results, ranging from criteria, such as focal neurologic deficit referable to the 18% to 90%. This broad range may be related to the ac- cervical spine, head injury (skull fracture, intracranial tual location of medication deposition. The incidence of hemorrhage) or loss of conscious at the time of examina- failure to reach the epidural space using a non–image- tion, and high-energy mechanism (motor vehicle accident guided transflaval approach ranges from 13% to 30% at a speed of greater than 35 mm, pedestrian struck by a and may target the wrong interlaminar space by one or car, or a fall greater than 10 feet). more levels. The transforaminal approach demonstrates superior ventral opacification, whereas the transflaval Diagnostic and Therapeutic Procedures method shows predominantly dorsal opacification (us- ing CT as the reference standard to confirm contrast lo- Spinal Injections cation after fluoroscopically-guided epidurography). Dorsal deposition may be less effective because the ste- Epidural steroid injections, sacroiliac joint injections, roid is remote from the source of irritation (for exa- zygapophyseal (facet) joint injections, diskography, and mple, disk herniation). There is an increased risk of a vertebral augmentation are image-guided procedures dural puncture (intrathecal administration), spinal head- that are important components of a comprehensive ache (may require blood patch treatment), intrathecal management approach to spine pain syndromes for es- administration of steroid or residual preservatives of lo- tablishing a diagnosis, directing or administering ther- cal anesthesia leading to nerve root injury, hypotension, apy, and facilitating rehabilitation and functional resto- or dyspnea. For several reasons image-guided epidural ration. steroid injection is favored; it adds only minimal risk (radiation) and may not add to the overall costs of spine Demand for epidural injections is rapidly expanding. injections but may even reduce costs by eliminating re- Patient satisfaction elicited from these procedures is of- peat injections (a nonimage-guided paradigm is to per- ten a direct result of imaging guidance, which can form two to three successive transflaval epidural steroid shorten and simplify procedures, minimize potential for injections because the miss rate of the epidural space is complications, and verify accurate localization of the about 33%). needle to selectively provide the lowest necessary dose of analgesic to the optimal area. These procedures can Intra-articular injections have an established role for greatly contribute to patient management and surgical identifying zygapophyseal (facet) and sacroiliac joint ar- planning by determining sources of pain and treating ticulations as nociceptors. However, intra-articular injec- pain generators. Participation of an experienced radiolo- tions with anesthetic or corticosteroid are often not suf- gist in performing these procedures optimizes patient ficient for a long lasting therapeutic effect. Once a care, because radiologists are trained in anatomy and zygapophyseal joint has been implicated as a substantial image-guided needle localization procedures. However, American Academy of Orthopaedic Surgeons 133

Musculoskeletal Imaging Orthopaedic Knowledge Update 8 Figure 11 CT characterization after intradiskal contrast injection. Postdiskography transaxial CT images. A, Normal nucleogram characterized by central globule of contrast material that remains within the expected confines of the nucleus pulposus. B, Annular fissure. Contrast material is noted within the nucleus pulposus, but also extends in a radial fashion posterolaterally beyond the expected confines of the nucleus pulposus into the region of the anulus fibrosus (arrow). There is also a circumferential component noted in the anulus fibrosus (arrowhead). or significant nociceptor then targeted therapy options indications include patients with persistent pain in exist that may include a neuroablative procedure (me- whom noninvasive imaging and other tests have not dial branch neurotomy) in conjunction with functional provided sufficient diagnostic information. In patients restoration via physical therapy. Sacroiliac joint treat- who are to undergo fusion, diskography can be used to ment can be more problematic given the diffuse inner- determine if disks within the proposed fusion segment vation of the articulation; however, sacroiliac joint fu- are symptomatic and if the adjacent disks are normal. sion is a technique practiced by some orthopaedic Surgeons concerned with limiting the extent of fusion surgeons. For true inflammatory sacroiliitis related to a are interested in obtaining more evidence beyond MRI spondyloarthropathy, there is good evidence from sev- abnormalities to document what intervertebral disk lev- eral clinical trials that intra-articular corticosteroid is els are contributing to the painful syndrome. In postop- proven to be an effective component of treatment. erative patients who continue to experience significant However, the data on the efficacy of steroid intra- pain, diskography can be used to assist in differentiating articular injections for mechanical somatic dysfunction between postoperative scar and recurrent disk hernia- are conflicting. For an intracanalicular synovial cyst em- tion (when MRI or CT is equivocal); or to evaluate seg- anating from an adjacent zygapophyseal joint that is ments adjacent to the arthrodesis. Postdiskography CT causing lateral recess stenosis with radicular symptoms, can also be used to confirm a contained disk herniation intra-articular injection with corticosteroid assists in de- as a prelude to minimally invasive intradiskal therapy creasing the perineural inflammation, reducing the size (Figure 11). Diskography is also being used as part of of the cyst, and alleviating the radicular symptoms. the selection criteria for many clinical trials assessing lumbar interbody fusion devices or percutaneous in- Diskography tradiskal treatments. The primary purpose for diskography is for documenta- Annotated Bibliography tion of the disk as a significant nociceptor. For patients who have chronic pain that is predominantly axial, non- Available Imaging Modalities myelopathic, and nonradicular, imaging may be insuffi- cient or equivocal for determining the nature, location, Carrino JA: Digital imaging overview. Semin Roentgenol and extent of symptomatic pathology. A position state- 2003;38:200-215. ment regarding lumbar diskography from the North American Spine Society was published in 1995. Specific This article provides an overview of the electronic imaging environment, including a review of the technologies behind 134 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 11 Musculoskeletal Imaging picture archiving and communications systems and radiology Recent reports and experience suggest that FDG-PET information systems as well as practical information on imple- cannot be a screening method for differential diagnosis be- mentation. tween benign and malignant musculoskeletal lesions, including many neoplasms originating from different tissues. FDG-PET Horton KM, Sheth S, Corl F, Fishman EK: Multidetector might not accurately reflect the malignant potential of muscu- row CT: Principles and clinical applications. Crit Rev loskeletal tumors, but rather might implicate cellular compo- Comput Tomogr 2002;43:143-181. nents included in the lesions. A high accumulation of FDG can be observed in histiocytic, fibroblastic, and some neurogenic This article reviews the basic principles of multislice com- lesions, regardless of whether they are benign or malignant. puted tomography. Scanner/detector design, beam collimation/ More specific uses of FDG-PET, such as grading, staging, and slice thickness, radiation dose, data manipulation, and display monitoring of musculoskeletal sarcomas, should be considered are discussed. for each tumor of a different histologic subtype. Jadvar H, Gamie S, Ramanna L, Conti PS: Musculoskel- Ecklund K, Jaramillo D: Patterns of premature phy- etal system. Semin Nucl Med 2004;34:254-261. seal arrest: MR imaging of 111 children. AJR Am J Roentgenol 2002;178:967-972. In this article, the diagnostic utility of dedicated PET and PET combined with CT in the evaluation of patients with The purpose of this study was to use MRI, especially fat- bone and soft-tissue malignancies is reviewed. suppressed three-dimensional spoiled gradient-recalled echo sequences, to identify patterns of growth arrest after physeal Recht M, Bobic V, Burstein D, et al: Magnetic resonance insult in children. This method exquisitely shows the growth imaging of articular cartilage. Clin Orthop 2001; disturbance and associated abnormalities that may follow phy- 391(suppl):S379-S396. seal injury, and guides surgical management. This article presents a review of procedures regarding Fardon DF, Milette PC: Nomenclature and classification MRI of articular cartilage and cartilage repair. Future direc- of lumbar disc pathology: Recommendations of the tions in imaging strategies and ways to measure cartilage combined task forces of the North American Spine So- thickness and volume are discussed. ciety, American Society of Spine Radiology, and Ameri- can Society of Neuroradiology. Spine 2001;26:E93-E113. Sofka CM: Ultrasound in sports medicine. Semin Musculoskelet Radiol 2004;8:17-27. This document provides a universally acceptable nomen- clature that is workable for all forms of observation, that ad- Ultrasound plays an important role in the evaluation of in- dresses contour, content, integrity, organization, and spatial re- juries and painful conditions of the athlete. With portable ultra- lationships of the lumbar disk; and that serves as a system of sound units, examinations can be performed on the playing field, classification and reporting built upon that nomenclature. immediately at the time of the acute injury, for rapid diagnosis. Ultrasound can be used to guide therapeutic procedures. Yoshioka H, Stevens K, Hargreaves BA, et al: Magnetic Karppinen J, Paakko E, Paassilta P, et al: Radiologic resonance imaging of articular cartilage of the knee: Com- phenotypes in lumbar MR imaging for a gene defect in parison between fat-suppressed three-dimensional SPGR the COL9A3 gene of type IX collagen. Radiology 2003; imaging, fat-suppressed FSE imaging, and fat-suppressed 227:143-148. three-dimensional DEFT imaging, and correlation with arthroscopy. J Magn Reson Imaging 2004;20:857-864. The results of this study indicate that the presence of Trp3 allele is associated with Scheuermann’s disease and interverte- In this study, signal to noise ratios and contrast to noise ra- bral disk degeneration. No associations were found for other tios were compared in various magnetic resonance sequences, radiologic phenotypes. including fat-suppressed three-dimensional spoiled gradient echo imaging, fat-suppressed fast spin echo imaging, and fat- Ledermann HP, Morrison WB, Schweitzer ME: MR im- suppressed three-dimentional driven equilibrium Fourier trans- age analysis of pedal osteomyelitis: Distribution, pat- form imaging. The diagnostic accuracy of these imaging se- terns of spread, and frequency of associated ulceration quences was compared with that of arthroscopy for detecting and septic arthritis. Radiology 2002;223:747-755. cartilage lesions in osteoarthritic knees. Fat-suppressed three- dimensional spoiled gradient echo imaging and fat-suppressed The purpose of this study was to evaluate the anatomic fast spin echo imaging showed high sensitivity and high negative distribution of pedal osteomyelitis and septic arthritis in a predictive values, but relatively low specificity. large patient group with advanced pedal infection and to com- pare ulcer location with the distribution of osteomyelitis and Imaging of Specific Orthopaedic Conditions septic arthritis. Pedal osteomyelitis results almost exclusively from contiguous infections and occurs most frequently around Aoki J, Endo K, Watanabe H, et al: FDG-PET for evalu- the fifth and first metatarsophalangeal joints. One third of pa- ating musculoskeletal tumors: A review. J Orthop Sci tients with advanced pedal infection show evidence of septic 2003;8:435-441. arthritis on MRI. American Academy of Orthopaedic Surgeons 135

Musculoskeletal Imaging Orthopaedic Knowledge Update 8 Philipp MO, Kubin K, Mang T, Hormann M, Metz VM: out injury to the cervical spine in patients with blunt Three-dimensional volume rendering of multidetector- trauma: National Emergency X-Radiography Utilization row CT data: Applicable for emergency radiology. Eur J Study Group. N Engl J Med 2000;343:94-99. Radiol 2003;48:33-38. Jensen MC, Brant-Zawadzki MN, Obuchowski N, et al: This article presents a review of recent literature on Magnetic resonance imaging of the lumbar spine in peo- ple without backpain. N Engl J Med 1994;331:69-73. volume-rendering technique and applications for the emer- gency department. Steinbach LS, Palmer WE, Schweitzer ME: Special focus Karasick D, Wapner KL: Hallux valgus deformity: Pre- session: MR arthrography. Radiographics 2002;22:1223- operative radiologic assessment. AJR Am J Roentgenol 1246. 1990;155:119-123. Direct magnetic resonance arthrography with injection of Lawson JP: International Skeletal Society Lecture in saline solution or diluted gadolinium can be useful for evaluat- honor of Howard D. Dorfman: Clinically significant ra- ing certain pathologic conditions in the joints. Indirect mag- diologic anatomic variants of the skeleton. AJR Am J netic resonance arthrography with intravenous administration Roentgenol 1994;163:249-255. of diluted gadolinium may be performed when direct magnetic resonance arthrography is inconvenient or not logistically fea- Martel W, Hayes JT, Duff IF: The pattern of bone ero- sible. Although indirect magnetic resonance arthrography has sion in the hand and wrist in rheumatoid arthritis. some disadvantages, it does not require fluoroscopic guidance Radiology 1965;84:204-214. or joint infection and is superior to conventional MRI in de- lineating structures when there is minimal joint fluid; vascular- Morrison WB, Schweitzer ME, Batte WG, Radack DP, ized or inflamed tissue will be enhanced with this method. Russel KM: Osteomyelitis of the foot: Relative impor- tance of primary and secondary MR imaging signs. Zlatkin MB, Rosner J: MR imagingof ligaments an tri- Radiology 1998;207:625-632. angular fibrocartilage complex of the wrist. Magn Reson Imaging Clin North Am 2004;12:301-331. Park YH, Lee JY, Moon SH, et al: MR arthrography of the labral capsular ligamentous complex in the shoul- This article summarizes the current diagnostic criteria that der: Imaging variations and pitfalls. AJR Am J can be useful in interpreting abnormalities of the wrist liga- Roentgenol 2000;175:667-672. ments and triangular fibrocartilage complex of the wrist. Diagnostic and Therapeutic Procedures Stoller DW, Martin C, Crues JV III, Kaplan L, Mink JH: Meniscal tears: Pathologic correlation with MR imaging. Carrino JA, Chan R, Vaccaro AR: Vertebral augmenta- Radiology 1987;163:731-735. tion: Vertebroplasty and kyphoplasty. Semin Roentgenol 2004;39:68-84. Weissman BN, Aliabadi P, Weinfeld MS, Thomas WH, Sosman JL: Prognostic features of atlantoaxial sublux- Vertebroplasty and kyphoplasty (balloon-assisted verte- ation in rheumatoid arthritis patients. Radiology 1982; broplasty) have both led to good pain relief and improved 144:745-751. function with minimal complication rates in appropriately se- lected patients when high-quality imaging and meticulous Winalski CS, Aliabadi P, Wright RJ, Shortkroff S, Sledge technique are used. CB, Weissman BN: Enhancement of joint fluid with in- travenously administered gadopentetate dimeglumine: Classic Bibliography technique, rationale, and implications. Radiology 1993;187:179-185. Hoffman JR, Mower WR, Wolfson AB, Todd KH, Zucker MI: Validity of a set of clinical criteria to rule 136 American Academy of Orthopaedic Surgeons

Chapter 12 Perioperative Medical Management Gregory Argyros, MD Introduction nation findings that identify subgroups of patients who are more likely to have abnormal results. Tests should Appropriate perioperative management of surgical pa- only be ordered if the result will influence management. tients is critical in ensuring the greatest likelihood of a If a test result is abnormal, documentation of the successful patient outcome. It is important to under- thought process regarding the planned response to the stand the physiologic response to surgery and anesthe- abnormality is critical. A summary of recommendations sia, disease-related and procedure-related risk, prophy- regarding testing before elective surgery is presented in lactic therapy to prevent perioperative problems, and Table 1. postoperative medical complications. The medical con- sultant must determine exactly what is being request- Cardiac Risk Assessment and Optimization ed—whether for surgical risk assessment, diagnostic or management advice, or documentation for legal reasons. The American College of Cardiology and the American The surgeon and the medical consultant must communi- Heart Association issued guidelines for perioperative cate directly to minimize the potential for misunder- cardiovascular evaluation of patients undergoing non- standing. cardiac surgery in 2002. They propose a stepwise strat- egy that relies on assessment of clinical markers, prior Surgical risk is the probability of an adverse out- coronary evaluation and treatment, functional capacity, come or death associated with surgery and anesthesia. and surgery-specific risk. A framework for determining Surgical risk is categorized into four components: pa- which patients are candidates for cardiac testing is pre- tient-related; procedure-related; provider-related; and sented in algorithmic form in Figure 1. anesthetic-related. Information from the medical his- tory, physical examination, review of available data, and Clinical markers are divided into major, intermedi- selectively ordered laboratory tests can be used to make ate, and minor predictors of increased perioperative car- an estimation of perioperative risk. The following fac- diovascular risk. Major clinical markers include an un- tors must be considered: the patient’s current health sta- stable coronary syndrome, such as a myocardial tus; if there is evidence of medical illness, how severe it infarction, within 1 month of surgery, unstable or severe is and whether it will affect surgical risk; how urgent is angina, evidence of a large ischemic burden by clinical the surgery; if surgery is delayed, will treatment of the symptoms or noninvasive testing, decompensated heart medical illness lessen its severity; and, if there is no rea- failure, significant arrhythmias, and severe valvular son to delay the surgery, what changes need to be made heart disease. Intermediate predictors are mild angina, a perioperatively to maximize the patient’s overall condi- myocardial infarction occurring more than 1 month be- tion. Assessment of these factors will allow for a deci- fore surgery, compensated heart failure, a preoperative sion on whether the patient is in optimal medical condi- creatinine level greater than 2.0 mg/dL, and diabetes. tion to undergo the planned surgical procedure. Minor predictors are advanced age, abnormal electro- cardiogram, heart rhythm other than sinus, low func- The Preoperative Evaluation tional capacity, history of stroke, and uncontrolled hy- pertension. The practice of extensive testing of all patients before surgery can be expensive, both in terms of direct costs Functional capacity can be expressed as metabolic of the tests, but also for the follow-up of unanticipated equivalent (MET) levels. Increasing MET levels reflect minor abnormalities, many of which have no clinical rel- a greater aerobic burden. Perioperative cardiac risk is evance. Many studies have shown that preoperative rou- increased in patients unable to meet a 4-MET demand tine testing of all patients is of limited value. Tests during most normal daily activities. Activities such as should be ordered based on history and physical exami- light housework, climbing a flight of stairs, or walking American Academy of Orthopaedic Surgeons 137

Perioperative Medical Management Orthopaedic Knowledge Update 8 Table 1 | Recommendations for Preoperative Testing postoperative deep venous thrombosis and pulmonary embolism. Test Indications Routine preoperative chest radiographs are not rec- Hemoglobin Anticipated major blood loss or symptoms of ommended for all patients. They should be obtained for anemia all patients older than 50 years, those with known preex- White blood cell isting cardiopulmonary disease, and those with symp- count Symptoms of infection, myeloproliferative disorder toms or findings on physical examination that suggest a or myelotoxic medications likelihood of cardiopulmonary disease. Using these cri- Platelet count teria, previously unrecognized abnormalities that may History of bleeding diathesis, myeloproliferative influence perioperative management will be detected in Prothrombin time disorder, or myelotoxic medications a small but clinically significant subset of patients. Partial thrombo- History of bleeding diathesis, chronic liver disease, The purpose of pulmonary function assessment in plastin time malnutrition, recent or long-term antibiotic use patients undergoing orthopaedic surgical procedures is not to preclude surgery but to help in anticipating and Electrolytes History of bleeding diathesis preventing complications. Preoperative pulmonary func- tion studies are typically not indicated unless the patient Renal function Know renal insufficiency, congestive heart failure, is older than 60 years, has a history of pulmonary dis- medications that affect electrolytes ease or smoking, or there is an anticipated anesthesia Glucose time of 2 hours or longer. Routine arterial blood gas as- Liver function tests Hypertension, age > 50 years, cardiac disease, sessments are not recommended. Urinalysis major surgery, anticipated use of medications Electrocardiogram that may affect renal function If possible, elective surgery should be delayed if the patient exhibits evidence of active infection (such as a Chest radiograph Obesity or known diabetes change in the character or amount of sputum). Also, sur- No indication gery should be delayed if the patient has obstructive No indication lung disease and is in the midst of an acute exacerba- Men > age 40 years, women > age 50 years, known tion. Although there is conflicting evidence regarding the benefits and ideal timing of smoking cessation be- coronary artery disease, diabetes, or hypertension fore surgery, abstinence from smoking for at least Age > 50 years, known cardiac or pulmonary dis- 8 weeks before surgery is probably ideal for decreasing postoperative pulmonary complications, but an 8-week ease, symptoms or examination suggestive of delay in surgery may not be feasible. Patients with ob- cardiac or pulmonary disease structive lung disease who are receiving bronchodilator or inhaled anti-inflammatory therapy should continue on level ground at 4 miles per hour involve a 4-MET this regimen throughout the perioperative period. energy expenditure. Although several abnormalities in pulmonary func- Surgery-specific risk is related to the type of surgery tion have been noted in obese patients, studies have and the degree of hemodynamic compromise associated shown that obesity does not consistently contribute to with the procedure. Most orthopaedic procedures are significant pulmonary complications. In patients with intermediate risk, with a cardiac risk generally less than known sleep apnea, perioperative airway management 5%. Prolonged procedures associated with large fluid is paramount because perioperative continuous positive shifts and/or blood loss and emergency surgery are high airway pressure may be required as these patients re- risk, with a reported cardiac risk of greater than 5%. cover from anesthesia. It has not been determined whether screening patients with multiple risk factors for Several trials have examined the impact of medical sleep apnea (obesity, increased neck circumference, therapy begun before surgery on reducing cardiac craniofacial abnormalities, hypothyroidism) impacts events. Two randomized, placebo-controlled trials of postoperative pulmonary complications, but concerns β-blocker administration have been performed, with about perioperative airway management difficulties one showing reduced perioperative cardiac events and should be raised. the other improved 6-month survival. When possible, β-blockers should be started far enough before elective Renal Risk Assessment/Optimization surgery so that the dose can be titrated to achieve a resting heart rate between 50 and 60 beats per minute. In patients with chronic kidney disease, cardiac disease is the leading cause of death; therefore, a full cardiac Pulmonary Risk Assessment/Optimization risk assessment as previously described is needed. In ad- dition, close attention must be paid to other manifesta- The type of surgery performed and the anatomic loca- tions of chronic kidney disease to include volume, elec- tion of the surgery are major determinants of risk in the development of postoperative pulmonary complications. Most orthopaedic procedures are associated with a very low incidence of pulmonary complications. Most of the complications that do occur involve either oversedation from pain medications that can result in atelectasis, or 138 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 12 Perioperative Medical Management Figure 1 Stepwise approach to preoperative cardiac assessment. Subsequent care may include cancellation or delay in surgery, coronary revascularization followed by noncar- diac surgery, or intensified care. (Reproduced with permission from Eagle KA, Berger PB, Calkins H, et al: ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery: Executive summary. Circulation 2002;105:1257-1267.) American Academy of Orthopaedic Surgeons 139

Perioperative Medical Management Orthopaedic Knowledge Update 8 on microscopic evaluation of the urine. These patients require volume repletion with a bicarbonate-containing resuscitation fluid to maintain an alkalotic urine. Figure 2 Summary of preoperative management recommendation based on thera- Diabetes Mellitus Risk Assessment and Optimization peutic regimen and the complexity and scheduling of the surgical procedure. MDI indi- cates multiple doses of intravenous insulin; IV, intravenous. (Reproduced with permis- Whenever possible, endocrine disorders should be iden- sion from Jacober SJ Sowers JR: An update on perioperative management of diabetes. tified and evaluated before surgery. The most common Arch Intern Med 1999;159:2405-2411.) endocrine disorder by far is diabetes mellitus. Patients with diabetes have an increased risk of perioperative trolyte, and acid/base status, anemia, bleeding diatheses, complications including infection, metabolic and elec- the propensity for dramatic swings in blood pressure, trolyte abnormalities, and renal and cardiac complica- and the need for dosage adjustments for many medica- tions. The stresses of surgery and anesthesia cause sev- tions. eral hormonal changes that contribute to hyperglycemia during and after surgery. The extent of the metabolic de- The high mortality rate of patients with postopera- rangements is related to the type and length of surgery. tive acute renal failure makes prevention a key objec- Several of the most significant consequences of periop- tive in overall management. Before surgery, particularly erative hyperglycemia include impaired wound healing for those procedures capable of inducing renal ischemia, and ability to fight infection. Patients with diabetes are potential risk factors such as volume depletion, hypoten- also at risk for hypoglycemia in the perioperative pe- sion, nephrotoxin exposure, and preexisting chronic kid- riod. This condition may go unrecognized in the patient ney disease must be identified. Elective surgery should under anesthesia if appropriate glucose monitoring is be delayed until any abnormalities are improved. Com- not performed. Factors that contribute to the risk of hy- mon nephrotoxins include nonsteroidal anti-inflam- poglycemia perioperatively include prolonged fasting, matory drugs, including selective cyclooxygenase inhibi- use of oral hypoglycemic medications, inadequate nutri- tors, certain antibiotics, angiotensin-converting enzyme tional state preoperatively, and postoperative gas- inhibitors, and radiocontrast. The use of these com- trointestinal problems. pounds must be monitored very closely and prophylac- tic regimens such as N-acetylcysteine before radiocon- How a patient’s diabetes is managed during surgery trast administration should be used. is dependent on several patient-specific and surgery- specific factors. Patient-related issues include whether Trauma patients with significant soft-tissue injury are treatment is with diet alone, with oral hypoglycemic at risk for developing acute renal failure from the myo- agents, or with insulin, as well as the degree of glycemic globin released from rhabdomyolysis. Acute renal fail- control. Surgery-specific factors to consider are the type ure should be suspected when dipstick urinalysis reveals of anesthesia, whether major or minor surgery is sched- the presence of heme when no red blood cells are seen uled, and how long the patient is expected to take noth- ing by mouth. Management algorithms for perioperative care of patients with diabetes are shown in Figures 2 and 3. Rheumatologic Disease Risk Assessment and Optimization Several unique perioperative issues must be addressed in the patient with rheumatologic disease. These issues are related to the disease itself, as well as the drug man- agement of many of these disease processes. Patients with rheumatoid arthritis are unique in their high rate of cervical disk disease. When the ligaments, bones, and joints that maintain C1-C2 stability are eroded by syno- vitis, C2 can subluxate on C1 and cause spinal cord com- pression. Manipulating the neck for intubation during general anesthesia stresses this joint and can result in spinal cord injury. It is estimated that up to 25% of rheumatoid arthritis patients have cervical disk disease, and these patients should be evaluated preoperatively. Rheumatoid arthritis patients are also at risk for cri- coarytenoid arthritis (seen in up to 50% to 80% in some 140 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 12 Perioperative Medical Management series). This condition can also make intubation very Figure 3 Management algorithm for oral hypoglycemic agents. SC indicates subcuta- difficult and, if suspected, indirect laryngoscopy should neously; IV, intravenous. (Reproduced with permission from Jacober SJ Sowers JR: An be performed preoperatively. update on perioperative management of diabetes. Arch Intern Med 1999;159:2405- 2411.) Anti-inflammatory drug and steroid use in patients with rheumatoid arthritis must be identified preopera- ment, depression, polypharmacy, and the presence of tively. Salicylates or nonsteroidal anti-inflammatory metabolic abnormalities. Evaluation of the elderly pa- drugs prolong bleeding time by inhibiting platelet aggre- tient who develops delirium requires consideration of gation. Relative risks of these medications vary with dif- preoperative, surgical, and postoperative factors. Preop- ferent surgical procedures, particularly if deep venous erative risk factors identified above should be corrected thrombosis prophylaxis is also going to be used. If possi- as much as possible, medication lists should be re- ble, salicylates and long-acting nonsteroidal medications viewed, unnecessary medications stopped, and careful should be discontinued 7 to 10 days preoperatively. In questioning about the use of over-the-counter medica- this instance, low-dose prednisone can often control in- tions and supplements should occur. Intraoperative fac- flammatory symptoms. tors associated with postoperative delirium include the type of surgery and anesthetic used. Hip fracture sur- Patients who have taken systemic steroid medica- gery (especially for femoral neck fractures) is a proce- tions for more than 1 week in the 6 months before sur- dure with a high risk for delirium. Anticholinergic gery should be considered for stress dosing of steroids agents, barbiturates, and benzodiazepines may also play during the perioperative period secondary to the risk of a role. Intraoperative hypotension or hypoxemia also hypothalamic-pituitary-adrenal axis suppression. Based are risk factors. Postoperative risk factors are similar to on the complexity/stress associated with the surgery, preoperative and intraoperative risk factors with reac- dosing recommendations can range from 100 mg of hy- tions to pain medications, particularly meperidine, also drocortisone given preoperatively, then every 8 hours playing a role. Sepsis, myocardial infarction, metabolic for the first day, decreased by 50% per day, and then abnormalities, and withdrawal from drugs or alcohol discontinued by the fourth day, to one dose of 50 to must be considered. For a patient with preexisting im- 100 mg of hydrocortisone immediately preoperatively as paired cognitive function, altered sensory input such as a single dose. not having eyeglasses or hearing aids available, or envi- ronmental changes can contribute to the development Perioperative Care in the Elderly of delirium. The perioperative management of the elderly has un- dergone major changes over the past 50 years because there has been a dramatic population shift. The age group 65 years and older is the fastest growing segment of the population in the United States, expected to com- prise 20% of the population by 2025. The contribution of individual patient conditions to surgical risk is related to a combination of physiologic changes associated with underlying diseases, combined to a lesser degree with age-related physiologic changes. Research has clarified that age alone is at most a minor risk factor for perioperative complications. Age-related cardiovascular, pulmonary, and renal changes have to be considered as well as recognition of altered pharmaco- kinetics in the elderly that can lead to an increase in complications and toxicity. Several postoperative complications are more com- mon in the elderly. Delirium is a clinical syndrome in which there is an acute disruption of attention and cog- nition. Orthopaedic patients, especially those with hip fracture, may have a 28% to 60% incidence of delirium. The development of postoperative delirium has been as- sociated with increased morbidity and mortality, so it is critical to identify patients who may be at risk and focus interventions on this group. Risk factors that have been identified include a history of drug or alcohol abuse, preexisting cognitive dysfunction or physical impair- American Academy of Orthopaedic Surgeons 141

Perioperative Medical Management Orthopaedic Knowledge Update 8 Immobility, another postoperative complication that Schiff RL, Welsh GA: Perioperative evaluation and can be devastating in the elderly, can lead to pressure management of the patient with endocrine dysfunction. ulcers, increased risk for osteoporosis, pulmonary risks Med Clin North Am 2003;87:175-192. such as atelectasis, increased risk of aspiration and pneumonia, increased risk of venous thromboembolic In this article, a discussion of current strategies for the pe- disease, and gastrointestinal, genitourinary, and cardio- rioperative evaluations and management of patients with dia- vascular effects. Elderly patients require an aggressive, betes mellitus is presented. multidisciplinary mobilization strategy that starts early and continues as long as is necessary for maximal func- Perioperative Care in the Elderly tional recovery. Beliveau MM, Multach M: Perioperative care for the In industrialized nations, the elderly are at perhaps elderly patient. Med Clin North Am 2003;87:273-290. the greatest risk of being malnourished, and it is impor- tant to identify these patients preoperatively. Elderly This article reviews perioperative strategies to decrease patients with preoperative malnutrition may develop the risk of complications in this patient population. protein-calorie malnutrition from the stress of surgery. Negative nitrogen balance depletes visceral protein Classic Bibliography stores, leading to a loss of muscle mass and less effective postoperative rehabilitation and ambulation. Nutritional Cygan R, Waitzkin H: Stopping and restarting medica- status should be monitored and addressed from the first tions in the perioperative period. J Gen Intern Med postoperative day and patients must not be allowed to 1987;2:270-283. fall behind nutritionally. Voluntary food intake should be monitored and nutritional supplements introduced Goldman L: Cardiac risks and complications of noncar- promptly if necessary. Oral supplementation is usually diac surgery. Ann Intern Med 1983;98:504-513. adequate and parenteral feeding should be used only as a last resort for patients with altered gastrointestinal Goldman L, Lee T, Rudd P: Ten commandments for ef- tract function. fective consultations. Arch Intern Med 1983;143:1753- 1755. Annotated Bibliography Kellerman PS: Perioperative care of the renal patient. The Preoperative Evaluation Arch Intern Med 1994;154:1674-1688. Arozullah AM, Conde MV, Lawrence VA: Preoperative Kroenke K, Gooby-Toedt D, Jackson JL: Chronic medi- evaluation for postoperative pulmonary complications. cations in the perioperative period. South Med J 1998; Med Clin North Am 2003;87:153-174. 91:358-364. A review of the morbidity, mortality, and risk factors asso- Mangano DT, Layug EL, Wallace A, et al: Effect of ciated with postoperative complications is presented. Indica- atenolol on mortality and cardiovascular morbidity after tions for preoperative tests and risk reduction strategies are noncardiac surgery. N Engl J Med 1996;335:1713-1720. discussed. Morrison RS, Chassin MR, Siu AL: The medical consult- Eagle KA, Berger PB, Calkins H, et al: ACC/AHA ant’s role in caring for patients with hip fracture. Ann guideline update for perioperative cardiovascular evalu- Intern Med 1998;128:1010-1020. ation for noncardiac surgery: Executive summary. Circulation 2002;105:1257-1267. Schiff RL, Emanuele MA: The surgical patient with dia- betes mellitus: Guidelines for management. J Gen Intern This article presents an overview of cardiovascular risk Med 1995;10:154-161. stratification for patients undergoing noncardiac surgery. Smetana GW: Preoperative pulmonary evaluation. Joseph AJ, Cohn SL: Perioperative care of the patient N Engl J Med 1999;340:937-944. with renal failure. Med Clin North Am 2003;87:193-210. Sorokin R: Management of the patient with rheumatic A discussion of recognition and elimination of risk factors diseases going to surgery. Med Clin North Am for development of acute renal failure is presented. Periopera- 1993;77:453-463. tive management of patient with end stage renal disease is re- viewed. 142 American Academy of Orthopaedic Surgeons

Chapter 13 Work-Related Illnesses, Cumulative Trauma, and Compensation Owen J. Moy, MD Robert H. Ablove, MD Introduction cases with as little expense as possible. The IME physi- cian is usually paid by the insurance carrier, which can It is difficult to estimate the overall cost of work-related build further bias into the system. The fact that there illness. There is little doubt that the involved costs are are so many parties with different interests can ulti- extraordinary. Most economic studies of work-related mately delay treatment and in some cases affect the ulti- illness focus on direct economic costs and disability du- mate outcome. Several basic terms necessary for a dis- ration. These studies place less emphasis on the signifi- cussion of this system are presented in Table 1. cant social implications of these injuries, such as the im- pact on the surrounding family and community. These Assessment of the Injured Worker costs are also often high, on both a social and economic level. Several parties usually perform medical assessment of the injured worker. The treating physician evaluates the The Workers’ Compensation System injured worker as he or she would any other patient, taking a thorough history of the injury, the patient’s oc- The origin of today’s workers’ compensation system in cupation, and any underlying conditions. the United States dates back to the turn of the 20th cen- tury when laws were enacted at both state and federal Social and psychological factors can play a large role levels to serve several purposes: paying workers’ medi- in disability. Conflicts with supervisors or associates, cal expenses, compensating workers for missed pay, and workplace stress, emotional problems, and substance or providing financial settlements for irrecoverable loss. alcohol abuse need to be explored and noted. Although there is considerable variation from state to state, the laws generally shield employers from charges The physical examination is obviously an important of negligence, thus mitigating the possibility of civil liti- part of the evaluation. Nonphysiologic findings need to gation. be explored and noted as potential evidence of malin- gering. Waddell described a simple list of five physical Workers’ compensation tends to function as an ad- signs to help establish a distinction between organic and vocacy system involving numerous parties, including the nonorganic findings in patients with low back pain (Ta- worker and possible legal representation, the treating ble 2). Findings of three or more positive signs are con- physician, the employer, the employer’s insurance car- sidered clinically significant. rier, case managers, and physicians performing indepen- dent medical examinations (IMEs). These examinations Following a thorough physical examination, the phy- are usually performed at the request of either the insur- sician formulates a treatment plan. In many cases, treat- ance carrier or the patient’s legal representation. Unfor- ment cannot commence without permission of the insur- tunately, the parties involved often have conflicting ance carrier. This is often the rate-limiting step in goals. providing definitive care for an injured worker. Most patients wish to receive care and get better, al- Depending on the cost of proposed treatment, the though there are often some noninjury-related issues or carrier may request an IME before initiation of nonur- barriers. On occasion patients may not want to return to gent care. The physician administering that examination work, because of issues as far ranging as a hostile work is theoretically rendering an independent opinion, but is environment to possible secondary monetary gain. Most being paid by the insurance carrier. At times, claimant treating physicians desire to administer care as expedi- attorneys may request additional “independent” exami- tiously as possible. Employers generally want employees nations. It is important to remember that the insurance to have as little sick or compensable time away as possi- adjuster’s main job is to limit the expense to the insur- ble, while their insurance carriers endeavor to resolve ance company of the administered care and that the American Academy of Orthopaedic Surgeons 143

Work-Related Illnesses, Cumulative Trauma, and Compensation Orthopaedic Knowledge Update 8 Table 1 |Basic Workers’ Compensation Terms Table 2 | Waddell’s Nonorganic Physical Signs in Low Back Pain Impairment Deviation from normal function, which may be 1. Tenderness Tenderness related to physical disease should Disability either permanent or temporary. be specific and localized to specific anatomic 2. Simulation Tests structures. Apportionment A nonmedical term pertaining to the loss or Superficial: tenderness to pinch or light touch diminution of the ability to perform a function 3. Distraction Tests over a wide area of lumbar skin. Loss of use or functions. It is possible to be impaired 4. Regional Nonanatomic: deep tenderness over a wide Maximal medical without necessarily being disabled. A tran- area, not localized to a specific structure. improvement scriptionist with a below-knee amputation has Disturbances an impairment but is still able to perform all 5. Overreaction These tests should not be uncomfortable. of his or her job functions. The terms are often Axial loading – reproduction of low back pain incorrectly used interchangeably. Disability with vertical pressure on the skull. may be partial or total as well as temporary Rotation – reproduction of back pain when or permanent. Disability determinations help shoulders and pelvis are passively rotated in establish the amount of ongoing financial the same plane. compensation received during periods of disability. The amount is usually a percentage Findings that are present during physical exam- of the regular salary. ination and disappear at other times, particu- larly while the patient is distracted. A term referring to the relative contribution of different factors to overall disability. This ap- Findings inconsistent with neuroanatomy. plies in cases of either underlying illnesses or Motor – nonanatomic “voluntary release” or prior injuries that make the current disability unexplained “giving way” of muscle groups. materially and substantially greater than it Sensory – nondermatomal sensory abnormali- would otherwise be. Both treating and inde- ties. pendent medical physicians are often asked to assign fixed percentages to the relative Disproportionate verbal or physical reactions. contributing factors. The occupational descriptions should include a list of Usually refers to a permanent relatively static the specific activities performed for each job, as well as loss of function, usually of an extremity. This is their frequency and duration. It is also important to a distinct category from disability. In certain note any recreational activity involving significant phys- states, loss of use determinations are used to ical exertion. Obviously, any history of other claims as help determine the appropriate lump sum well as nonwork-related injuries or illnesses should be settlement necessary to settle a case. documented. The point at which no further recovery from an injury or illness is expected. IME physician may be under pressure to render a favor- Interacting With the Caseworker able decision for the carrier. Many insurance companies hire caseworkers to manage Functional capacity evaluations are an attempt to individual claims. Under ideal circumstances, they can create an objective measurement of physical capabili- expedite patient care, and manage the transition from ties. They are a useful adjunct in determining work rehabilitation to work hardening (discussed in more de- readiness and are at the very least more objective than tail later in this chapter) to the ultimate return to work. arbitrary physician estimates. They also can provide evi- dence of submaximal or inconsistent patient effort, The caseworker’s main role should be facilitating which may be of use in detecting malingering. Unfortu- communication between the involved parties. To be ef- nately, they also provide an additional layer of expenses fective, the caseworker needs to be conversant in ortho- to the care of injured workers. paedic and ergonomic issues (see next section). Specific ergonomic training increases caseworker effectiveness. Points of Documentation The caseworker can accompany the patient to office vis- its and learn their specific work capabilities. A job site Typically, the first step in the filing of a claim is to fill visit, including both an ergonomic assessment of the out an incident report. However, these reports are at workstation and a discussion with the employer regard- times filed retrospectively after treatment has already ing availability of specific light duty positions, can help been sought and possibly initiated, either via out-of- speed the return to work. pocket expense or private insurance. Patients need to be informed of the role of the case- A detailed, specific occupational history including a worker as well as their own right to privacy. Given the list of current and previous occupations is paramount. organization of most current workers’ compensation systems, caseworkers can be very effective. Because 144 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 13 Work-Related Illnesses, Cumulative Trauma, and Compensation the employer’s insurance carrier employs the casework- Does This Exist and Is It an Epidemic? ers, it also is possible that bias can be introduced into the system. There is little doubt that CTDs exist, but that does not mean that they are easy to describe or quantify. If a Cumulative Trauma Disorders and Ergonomics body is exposed to repetitive force over time, given enough repetitions the body will show signs of wear. What is the Concept? Many CTDs have multifactorial causes and represent changes that may have occurred over a significant time Cumulative trauma disorders (CTDs) is a term applying period. Controversy exists because an immediate cause to health disorders arising from repetitive biomechani- and ultimate responsibility for CTDs can therefore be cal stress. A discussion of ergonomics is central to this hard to determine. topic. Ergonomics is a relatively recent word, dating to approximately 1945, defined as a branch of ecology per- With carpal tunnel syndrome, for example, there is taining to human factors in machine design and opera- support in the literature for the role of extreme wrist tion as well as the physical environment. The Occupa- position and vibration exposure in the development of tional Safety and Health Administration’s (OSHA) the condition, both of which are potential occupational current definitions of ergonomics listed on their website causes. Many nonoccupational causes exist, including include both the science of fitting the job to the worker gender, obesity, tobacco use, and diabetes. Therefore, it and the practice of designing equipment and tasks con- is difficult to ascribe causation to one particular factor. forming to workers’ capabilities. The situation is similar with other CTDs. This issue is paramount in workers’ compensation because causation The Occupational Safety and Health Act of 1970 plays a key role in who ultimately pays for care. states that it is the employer’s responsibility to provide a workplace free from serious hazards. This includes the Further epidemiologic study is necessary to estimate prevention of ergonomic hazards. To meet these goals, relative causation in diseases with more than one risk OSHA has developed a series of manuals and programs factor and ergonomic intervention needs to be preferen- to help employers meet workers’ ergonomic needs that tially directed toward high-risk groups. High-risk groups include a generalized framework of health and safety include patients with multiple claims, multiple medical programs as well as guidelines for specific industries. problems, and prolonged absence from work. These guidelines have been developed with the assis- tance of the National Institute for Occupational Safety Legal Issues in Occupational Medicine and Health, current scientific information, the medical literature, and OSHA’s own enforcement experience. Workers’ compensation is generally set up as a no-fault system. As such, employers are legally shielded from be- Specifically, the guidelines include a process for pro- ing sued for negligence. Many of the legal issues focus tecting workers as well as a means of identifying specific therefore on causal relationship, degree of ongoing dis- problems and implementing solutions. There are also ability, and ultimate disability settlement. sections on task-specific training. Appropriately, most of the focus is on prevention. Causal relationship is the key factor that determines who pays for care. The clinician must be careful to docu- CTDs refer to disorders from trauma occurring over ment any evidence of a presumed causally-related ill- time, rather than from one specific incident. In the early ness or injury. It is also important to document any his- 1990s there was a significant increase in the reporting of tory of prior illnesses and injuries, especially any that CTDs. According to the Bureau of Labor, statistics from resulted in missed work. Patients’ recreational and other that time show that CTDs represented half of the occu- nonoccupational activities need to be carefully noted. pational illnesses reported in their annual survey. The The duration and relative number of repetitions of both very term cumulative trauma disorder is fraught with work and nonwork activities should be dutifully re- controversy because it implies a level of a presumed corded. If there is any possible evidence that an injury is knowledge regarding the etiology of certain conditions, not causally related, an insurance carrier is likely to at- which does not necessarily exist. OSHA literature now tempt to avoid payment for the condition. Direct com- uses the less specific and therefore more benign term munication with the insurance adjuster can sometimes musculoskeletal disorders. OSHA manuals mention low help expedite care decisions. back pain, sciatica, rotator cuff injuries, epicondylitis, and carpal tunnel syndrome as common musculoskeletal Assignment of Disability disorders, conceding that more needs to be learned about the connection between the workplace and these Disability Rating disorders. Because disability is not a medical term, disability rating is not based solely on medical factors. Disability can be partial or total as well as temporary or permanent. Cer- tain states publish guidelines giving criteria for types of partial disability. Ultimately, the physician makes a American Academy of Orthopaedic Surgeons 145

Work-Related Illnesses, Cumulative Trauma, and Compensation Orthopaedic Knowledge Update 8 somewhat arbitrary determination of whether or not the One area of recent controversy has been docu- patient is capable of performing his or her job and to mented reports of insurance companies altering reports what degree. Administrative panels or workers’ com- as well as requesting specific opinions and wording from pensation judges often settle disputes and make final the examining physician. Presumably because of this, the determinations. state of New York recently changed regulations regard- ing reports, specifying that they can only be issued after Disputes can arise between worker and employer being read and signed by the examining physician. over the issue of partial disability. Insurance carriers of- ten urge physicians to state that patients are available The certification process for qualified medical exam- for light duty and thus not totally disabled. Unfortu- iners is an evolving process and varies considerably nately, they often make these urgings in the absence of from state to state. In the state of New York, laws have firsthand knowledge regarding the workplace and the recently changed requiring that examining physicians be availability of specific types of light duty. Another prob- board certified. Ironically, there is no such requirement lem with so-called light duty designations is that they of treating physicians, allowing the possibility that a sur- are often not job-specific and only provide simple lifting geon may legally operate on compensation patients, but and time restrictions. Caseworker jobsite visits and com- not be able to render independent opinions. munication with the physician, patient, and employer can help resolve some of these issues. In addition to orthopaedic board certification, there are other types of certification such as those by the Role and Certification of the Qualified board of disability examiners, which enable physician credentialing, and courses on occupational orthopaedics Medical Examiner and workers’ compensation. The theoretical role of the qualified medical examiner is Return to Work Strategies to provide an independent opinion regarding the pa- tients’ illness or injury as well as the care they have re- The Maximal Medical Improvement Concept ceived. These are most commonly requested and paid for by the employer’s insurance carrier. The typical as- As stated earlier, maximal medical improvement is the sessment usually includes a history of present illness, point at which no further improvement is generally ex- past medical and surgical history, occupational and so- pected. When this occurs, the patient is evaluated to de- cial history, record review, physical examination, and the termine if there is any permanent impairment. In cases formulation of an opinion. Examiners are usually asked of permanent impairment, a final settlement is made. to comment on specific issues requested by the carrier Different criteria exist for establishing these settle- and not to offer unsolicited opinions. Commonly, opin- ments, which can be grouped into three main categories: ions are requested regarding diagnosis, causal relation- functional, anatomic, and diagnostic. ship, treatment to date, further treatment recommenda- tions, and degree of disability. In certain instances where The functional impairment system is based on what there have been prior injuries or underlying illnesses, effect the impairment has had on the ability to work. examiners may comment on apportionment. The anatomic system is based on the loss of a body part. An amputation is a 100% loss; lesser injuries are quanti- The IME is often a rate-limiting step of workers’ fied via mobility, sensibility, and strength measurements compensation care. Insurance adjusters commonly as compared with normal findings. The diagnostic sys- refuse to authorize diagnostic testing as well as both sur- tem is based on the diagnosis code. All of these tech- gical and nonsurgical care without a concurring inde- niques are incorporated into the Fifth Edition of the pendent opinion. If the treating and independent opin- American Medical Association Guides to the Evaluation ions differ, a compensation judge or administrative of Permanent Impairment. panel often has to settle the dispute. These steps can de- lay care for many months. Generally, most states rely on some form of the ana- tomic system to determine final settlement sums. The There continues to be a lack of consensus regarding state of New York divides final determinations into loss how to manage workers’ compensation claims. Typically of use and disability. In static cases of extremity injuries and predictably, the more say patients have in their care in which patients are not completely disabled and fur- the more satisfied they are with the outcome. However, ther dramatic deterioration in function is not expected, this does not consistently result in measurable outcome a percentage loss of use is determined based on the in- differences. The prevailing fear against allowing more volved body part. The award is then based on that per- patient and physician autonomy is that costs will rise. centage as well as the occupation and income level of However, experience has thus far not borne out this the injured worker. fear. In fact, there has been evidence that increased us- age of musculoskeletal specialists tends to decrease Patients with neck and back problems as well as ex- overall costs. Additional prospective study is necessary. tremity injuries involving ongoing significant disability, particularly where further deterioration is expected, 146 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 13 Work-Related Illnesses, Cumulative Trauma, and Compensation may be classified as permanently disabled on either a This article studies the effect of using visiting musculoskel- partial or total basis. etal specialists to assist primary care physicians. Claim costs were significantly lower in this system than in a typical work- Wisconsin uses a modification of the no-fault system. ers’ compensation managed care model. Awards can be increased or decreased in cases of unsafe work places and unsafe work practices, respectively. Bernacki EJ, Tsai SP: Ten years experience using an in- tegrated workers’ compensation management system to Minnesota is one of the only states to rely on diag- control workers compensation costs. J Occup Environ nosis codes to determine impairment, whereas Califor- Med 2003;45:508-516. nia is one of the only states to rely on functional deter- mination. Regardless of the system, one must remain This article examines the positive effect of an integrative cognizant of the distinction between disability and im- approach to managing workers’ compensation claims. It pre- pairment and make a determination based on the guide- sents 10 years of experience using a small group of health care lines of the particular system. providers who address both physical and psychological needs. It also illustrates the importance of maintaining open lines of Work Hardening: How Does This Work? communication between all involved parties. Work hardening is an intermediate step between ther- Durand MJ, Loisel P, Hong QN, Charpentier N: Helping apy and return to work. It has evolved over the past two clinicians in work disability prevention: The work dis- decades as an outgrowth of traditional rehabilitation. A ability diagnosis interview. J Occup Rehabil 2002;12:191- work-like environment is created for the recovering 204. worker, who is then able to build both physical stamina and psychological confidence by replicating work activi- This article illuminates the multifactorial nature of muscu- ties in a controlled environment. loskeletal disorders. It describes the development of a work disability diagnosis interview as a means of helping detect In this unique setting, the therapist provides prognostic factors in musculoskeletal pain patients. occupation-specific ergonomic instruction, hopefully minimizing risk factors for re-injury upon return to Gross DP, Battie MC: Reliability of safe maximum lift- work. Although additional prospective controlled effi- ing determinations of a functional capacity evaluation. cacy studies of work hardening would be helpful, there Phys Ther 2002;82:264-271. already exists significant documented evidence of its benefits. Functional capacity evaluations are evaluated for both in- terrater and test-retest reliability. Overall, functional capacity Summary evaluations demonstrated excellent interrater and good test- retest reproducibility. The greatest source of variability was in- The intent of the workers’ compensation system is ad- consistent patient performance. mirable, namely treating and compensating workers for work-related injuries. Ultimately that intent is usually Harper JD: Determining foot and ankle impairments by realized. Most of the patient and physician dissatisfac- the AMA Fifth Edition guides. Foot Ankle Clin 2002;7: tion with the system stems from the mode and timing of 291-303. rendered care. Unfortunately, most state systems are cumbersome with multiple layers of administration, This article describes how to determine impairments based leading simultaneously to delayed care delivery and in- on the American Medical Association Fifth Edition guide. It creased overall costs. offers a good discussion of the different techniques of deter- mining impairment and the difficulty of accounting for pain as Several states have experimented with different part of this determination. models of administered care. Successful strategies in- clude more integrated care, increased physician auton- Lincoln AE, Feuerstein M, Shaw WS: MillerVI: Impact omy, increased specialist involvement, and use of well- of case manager training on worksite accommodations trained case managers. Additional study is necessary. in workers’ compensation claimants with upper extrem- Hopefully, in the coming years, some of these strategies ity disorders. J Occup Environ Med 2002;44:237-245. can be implemented on a larger scale. This is a case control study that illustrates the effect of a Annotated Bibliography two-day training course on the ability of nurse case managers to design and implement workplace changes. The trained Atcheson SG, Brunner RL, Greenwald EJ, Rivera VG, nurses offered more specific accommodations and modifica- Cox JC, Bigos SJ: Paying doctors more: Use of muscu- tions whereas the untrained nurses more often recommended loskeletal specialists and increased physicians pay to de- light duty and lifting restrictions. crease worker’s compensation cost. J Occup Environ Med 2001;43:672-679. Schonstein E, Kenny DT, Keating J, Koes BW: Work conditioning, work hardening and functional restoration American Academy of Orthopaedic Surgeons 147

Work-Related Illnesses, Cumulative Trauma, and Compensation Orthopaedic Knowledge Update 8 for workers with back and neck pain, Cochrane Data- Classic Bibliography base System Review (on CD-ROM). 2003;(1) CD001822. Cocchiarella L, Anderson GBJ (eds): Guides to the Evaluation of Permanent Impairment, ed 5. Chicago, IL, This article compares the effectiveness of management American Medical Association, 2000. strategies for return to work in patients with back and neck pain. Patients with chronic back pain benefited from physical Creighton J: Workers’ compensation and job disability, conditioning, even when non-job specific, having a reduced in Peimer CA (ed): Surgery of the Hand and Upper Ex- number of sick days compared with patients who did not un- tremity. McGraw Hill, 1996, pp 2345-2351. dergo physical conditioning. US Department of Labor: Guidelines for Nursing Gordon SL, Blair SJ, Fine LJ (eds): Repetitive Motion Homes: Ergonomics for the Prevention of Musculoskele- Disorders of the Upper Extremity. Rosemont, IL, Ameri- tal Disorders. OSHA 2003;3182. can Academy of Orthopedic Surgeons, 1995. This manual is a one of a series for different industries Lepping V: Work hardening: A valuable resource for the commissioned by Elaine Chao, United States Secretary of La- occupational health nurse. AAOHN J 1990;38:313-317. bor, as part of an overall strategy to reduce ergonomic inju- ries. It provides both a process for protecting workers and Lieber SJ, Rudy TE, Boston JR: Effects of body me- identifies solutions for specific work-related problems. chanics training on performance of repetitive lifting. Am J Occup Ther 2000;54:166-175. US Department of Labor: All About OSHA Occupa- tional Safety and Health Administration. OSHA 2003; Luck JV Jr, Florence DW: A brief history and compara- 2056-07R. tive analysis of disability systems and impairment rating systems. Orthop Clin North Am 1988;19:839-844. This manual describes the origin and function of OSHA. It also provides a concise summary of state programs, standards Norris CR: Understanding Workers’ Compensation and guidance, as well as available programs and services. Law. Hand Clin 1993;9:231-239. Wickizer TM, Franklin G, Plaeger-Brockway R, Mootz US Department of Labor: Ergonomics Program Man- RD: Improving the quality of workers’ compensation agement Guidelines for Meatpacking Plants. (OSHA) health care delivery: The Washington State Occupa- 1993;3123. tional Health Services Project. Milbank Q 2001;79:5-33. Waddell G, McCulloch JA, Kummel E, Venner RM: This is a summary of research and policy adopted in Wash- Nonorganic physical sign in low back pain. Spine ington State over recent years to identify and correct prob- 1980;5:117-125. lems resulting in poor care and increased disability for injured workers. It points to a lack of integrative occupational health services as the most powerful predictor of adverse results. 148 American Academy of Orthopaedic Surgeons

Chapter 14 Medical Care of Athletes Mark Anthony Duca, MD Introduction The Preparticipation Evaluation The physician’s role in the medical care of athletes has The goal of the preparticipation evaluation, defined as become increasingly complex as the understanding of the assessment of an individual athlete’s qualification to physiology and its application to athletic performance compete in a particular sport or activity, is multifaceted. expands. With ever-developing technologies and ongo- The preparticipation evaluation must be comprehensive, ing research to improve the care of the athlete, the re- yet at the same time sport-specific and focused, in an at- sponsibilities of the team physician have grown rapidly. tempt to identify any illness or conditions that predis- pose the athlete to injury, assess appropriateness for The care of an individual athlete often requires a participation, and identify athletes at risk for specific, multidisciplinary approach. Expert opinions may be re- sport-related injuries. For example, a detailed ocular and quired from many medical specialties, and it is the role visual acuity examination would be much more impor- of the team physician to serve as the gatekeeper and li- tant to the competitive archer than the Olympic swim- aison between the athlete and the health care system. mer; similar sports-specific factors should to be taken into consideration when preparing for the evaluation. Medical care of athletes now not only requires an ability to assess and diagnose but a unique skill in coor- The timing and frequency of the preparticipation dinating an overall game plan for their management. evaluation should be completed at least 4 to 6 weeks be- The role of the team physician has evolved from one in fore competition. The optimal frequency of the exami- which preparticipation qualification and game-time in- nation has been debated in the literature. Annual exam- jury management were sole responsibilities to one in inations with health maintenance and training which coordination of medical expertise with other counseling have been advocated. Another approach has health-related professionals such as medical specialists, been a baseline examination at any new level of compe- athletic trainers, nutritionists, pharmacists, physical ther- tition followed by interval history review at the begin- apists, and psychologists is essential. This dialog leads to ning of each new season. The examination may need to the safe participation of the athlete and maximizing of be done much more frequently, particularly with ath- their potential. letes who participate in multiple sports throughout the year. The medical management of the athlete not only re- quires the ability to coordinate the preparticipation as- The examination is divided into the history and sessment with management of on-the-field injuries, but physical. Patient history is essential in identifying ath- also the skill to outline a plan for rehabilitation and re- letes at risk for a particular injury. A standardized, turn to participation after an injury or illness. health-history questionnaire, completed by the athlete and reviewed by a health-related professional, can be The team physician must also be adept with proper very helpful (Figure 1). This tool can be modified for documentation when it comes to the care of athletes specific sports and improve the efficiency of the evalua- and equally skilled at communicating treatment plans tion. with coaches, administrators, media, agents, and family members. The team physician must also communicate The physical examination is an assessment of overall with others in a way that does not violate patient confi- general health, with specific focus on organ systems per- dentiality and is in strict compliance with Health Insur- tinent to the athlete’s history or central to safe partici- ance Portability and Accountability Act guidelines. pation in their particular sport. Vital information includ- ing height, weight, blood pressure, heart and respiratory Athletic care from a medical standpoint, whether it rates, and more recently, body mass index, should be re- be for an elite, recreational, or nonprofessional athlete, corded for every potential participant, and common requires a detailed understanding of basic principles and standards of care. American Academy of Orthopaedic Surgeons 149

Medical Care of Athletes Orthopaedic Knowledge Update 8 Figure 1 Sample preparticipation examination health questionnaire. (Reproduced with permission from Fields KB: Preparticipation evaluation of the school athlete, in Rich- mond JC, Shahaday EJ, Fields KB (eds): Sports Medicine for Primary Care. Ann Arbor, MI, Blackwell Science, 1996, p 68.) 150 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 14 Medical Care of Athletes Table 1 | Classification of Sports by Contact Table 2 | Medical Conditions Affecting Sports Participation Contact Noncontact Conditions Requiring Clearance Before Sports Participation Collision/Contact Limited Contact Strenuous Nonstrenuous Atlantoaxial instability Hypertension Basketball Baseball Dancing Archery Dysrhythmia Field hockey Cycling Heart murmur/valvular heart disease Football Diving Discus Bowling Diabetes mellitus Ice hockey Fencing Heat illness history Lacrosse Field Javelin Golf Hepatomegaly, splenomegaly Martial arts High jump History of repeated concussion Soccer Pole vault Shot put Rifle Asthma Water polo Gymnastics Absent/undescended testicle Wrestling Raquetball Rowing One-eyed athletes or athletes with vision < 20/40 in one eye Skating Bleeding diathesis Skiing Running/Cross Congenital heart disease Softball Seizure disorder Volleyball country Febrile illness Eating disorders Strength training One-kidney athletes Malignancy Swimming Organ transplant recipient Obesity Tennis Dermatologic disorder Track ment of a conditioning program. Whether it be sport- specific or for general overall fitness, concepts such as general health problems such as obesity and hyperten- specificity, prioritization, periodization, and work over- sion should quickly be identified. Multiple studies have load need to be addressed. Also, it needs to be under- directly linked increased body mass indices with in- stood that conditioning and readiness is a combined creased morbidity and mortality rates. Recent, stricter product of overall general fitness, sport-specific fitness, blood pressure screening guidelines established for the and skills specific to the individual sport. Becoming fa- general public will no doubt affect preparticipation ex- miliar with calculation of workloads for the purpose of aminations as well. outlining a conditioning and fitness program using heart rates and metabolic measurements such as maximum The role of screening tests in the routine medical oxygen consumption (MVO2) can be useful as well. evaluation of athletes remains unproven. Many studies, looking at long-term benefits of screening modalities Conditioning specificity refers to the unique condi- such as electrocardiograms, echocardiograms, or even tioning demands of an individual sport and the neces- urinalysis and chemistry screening profiles, have repeat- sary adjustments an athlete has to make to accommo- edly failed to show any clear benefit. Thus, at this time date those demands. Each sport has differences in these screening tests cannot be universally recom- muscle groups needed, aerobic capacity, flexibility, envi- mended unless specifically indicated by the history or ronmental and even psychological factors. Thus, the spe- physical examination. cifics of a conditioning program are adjusted to meet these particular demands. Clearance for participation and fitness assessment is dependent on the preparticipation physical examina- Prioritization refers to different levels of emphasis tion. The results of the examination then must be evalu- placed on certain components of a conditioning pro- ated in conjunction with the specific demands of the gram based on the athlete’s preference with varying lev- sport before a final determination on clearance for par- els of input from coaches, trainers, and ultimately, physi- ticipation can be made. Sport-specific requirements such cians. Basketball players looking to improve their as degree of exertion, degree of contact, agility, and en- jumping ability may prioritize lower extremity strength- vironmental influences play a role in determining eligi- ening and agility training much in the same way a base- bility (Tables 1 and 2). The team physician must be skilled and knowledge- able about acting on any clearance recommendations. A willingness to clearly communicate and document the results of the preparticipation evaluation with the ath- lete must be established. It is preferable that the exam- ining physician coordinate any follow-up required to complete or change the clearance determination. Conditioning and Preparation Several basic principles of conditioning must be under- stood to provide medical consultation in the develop- American Academy of Orthopaedic Surgeons 151

Medical Care of Athletes Orthopaedic Knowledge Update 8 ball pitcher may emphasize upper extremity and arm bility is the ability of joints and particular muscle groups flexibility workouts. to maximize their natural range of motion without com- promising strength and endurance. Certainly flexibility Periodization refers to a planned variation in inten- can vary from athlete to athlete. Thus, no set standard sity and duration of a specific workout over a pre- can be developed for outlining a flexibility program. A defined duration of time. A distance runner training for large body of evidence suggests that improved flexibility an upcoming marathon uses periodization as a condi- decreases risk for injury although few data exist to im- tioning method by changing the length in miles and in- ply improved performance. tensity measured in speed at each training session be- fore competition. The ultimate goal of periodization is In contrast to flexibility, specific standards and obtaining maximal performance based on the concept of guidelines can be developed for both aerobic capacity progressive overload, one at which conditioning is and strength training. For aerobic training, three meth- started at moderate tolerable levels of exertion and pro- ods are preferred to establish training guidelines. The gressively pushed to maximum exertion. Multiple stud- first, which is relatively easy to calculate, uses the maxi- ies have demonstrated this method of conditioning is su- mum heart rate as a predictor of intensity. The sug- perior to training techniques in which intensity and gested intensity level is expressed as a percentage of the duration of training are kept constant over a given pe- maximal predicted HR. The target HR for conditioning riod of time. Periodization cycles are defined by length should be 60% to 90% of the maximum HR. A more of time and are referred to as macrocycles, mesocycles, highly competitive athlete would aim for a larger per- or microcycles. Macrocycles generally refer to an entire centage of the maximum rate, whereas the daily jogger training year (season to season), mesocycles 3 to trying to stay in shape may use a lower percentage. For 6 months, and microcycles 3 to 6 weeks. Multiple vari- example, a 40-year-old recreational jogger may use 75% ables can be adjusted during a periodization cycle in ad- of his maximum HR to calculate his target HR. Calcula- dition to intensity and duration of a conditioning work- tion of the maximum predicted HR is done by subtract- out. They can include variations in types of exercises, ing his age from 220. In this instance it would be 180 number of repetitions of individual exercises, or length beats per minute (bpm); 180 is then multiplied by 0.75 of rest periods between exercises. for a product of 135, which now becomes a projected target HR of 135 bpm. The second method requires a Conditioning can be further defined as a product of few simple calculations. First, the maximal predicted HR aerobic capacity, strength, and flexibility. Aerobic capac- is established (example: age 40; 220 – 40 = 180 bpm HR ity cannot only be subjectively measured by perfor- maximum). Next, the HR reserve is calculated by sub- mance, but also objectively by measurement of the tracting the resting HR from the maximal predicted MVO2 or VO2max, referred to as maximum oxygen up- HR. The HR reserve is then multiplied by an intensity take. MVO2 represents the maximum oxygen-carrying factor based on an individual athlete’s goals and level of capacity of the oxygen transport system, which drives conditioning. A beginner should use an intensity factor adenosine triphosphate (ATP) synthesis during aerobic in the range of 50% to 65% of HR reserve. A moderate metabolism. The oxygen transport system allows tissue conditioned or recreational athlete should use 65% to to extract oxygen from oxygenated blood and synthesize 75% of HR reserve. Finally, a highly conditioned athlete ATP for energy for muscle activity. A very efficient sys- trying to maximize aerobic capacity for competition tem allows for maximum performance. The MVO2 is de- uses 75% to 85% of HR reserve. The product of the HR fined as the product of heart rate (HR), stroke volume reserve and intensity factor (example: HR reserve 140 × (SV), and the difference between arterial and mixed 0.70 for a recreational athlete) is then added to the rest- venous oxygen concentrations (a – VO2), or: MVO2 = ing HR to calculate the target exercise HR. HR × SV × a – VO2. A third method, which requires direct measurement HR times SV is referred to as the cardiac output, of MVO2 via calorimetry during maximal exercise stress whereas SV is the difference in left ventricular volume testing, is less practical but ultimately more accurate between end diastole and end systole. Routine measure- than the second method. Similar to the HR method, the ment of MVO2 is not practical because it requires the oximetry method establishes the target as a percentage use of a calorimeter, which may not be readily available. of the MVO2 obtained during maximum exercise testing. Similar intensity factors are used as guidelines for these Strength is an integral component to overall condi- percentages. For example, an elite athlete should target tioning and fitness and is defined as the ability of a par- 75% to 85% of the MVO2 as his conditioning intensity ticular muscle or muscle group to perform work. Al- whereas an intermediate or novice athlete would target though specific strength training programs are beyond ranges from 65% to 75% and 55% to 65%, respectively. the scope of this chapter, the concepts mentioned earlier A relationship can then be established between heart of specificity, periodization, and progressive work over- rate and VO2 during exercise testing to determine a tar- load all apply here as well. get HR for training. Flexibility training and development represents the final component of a total conditioning program. Flexi- 152 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 14 Medical Care of Athletes Much in the way HR or MVO2 are central to devel- competition, and involves review of the athlete’s pro- oping guidelines for aerobic training, the repetition posed competition schedule. maximum (RM) can be used for developing strength- training guidelines. The repetition maximum, or 1-RM, Medical care of the athlete involves coordination of is defined as the maximum amount of weight or resis- administrative duties such as establishment and docu- tance that can be lifted for one repetition. An RM also mentation of an emergency response plan for the seri- refers to a specific number of repetitions limited by a ously ill or injured competitor. Additionally, a policy to particular weight or resistance. For example, a weight assess playing condition and environmental factors at that can be lifted 10 times until fatigue would be 10- the time of competition must be established, and a pro- RM. A preferable utilization of the RM allows the pre- tocol involving administrators, competition officials, scriber to establish an RM training zone based on the coaches, and staff to make an educated decision regard- target goal of strength training. A training zone is usu- ing safe competition conditions should be clearly delin- ally a range of three RMs (eg, 8 to 10 RM), which re- eated. Finally, medical record keeping is essential in the duces the need to exercise to fatigue with each set. care of athletes and preseason planning should ensure that this takes place. The concept of specificity mentioned earlier can be applied to strength training based on the goals and de- Game-day preparations and operations involve the mands of an individual athlete’s sport. Four common assessment and management of game-day injuries and variables may be adjusted within the training program illnesses and final determinations on clearance for par- to achieve target goals. The RM, number of repetitions, ticipation. A review of game-time playing conditions is number of sets, and rest period between sets can all be conducted according to the established preseason policy adjusted to optimize power, strength, and endurance. and any concerns should be promptly brought to the at- Exercises focusing on improvements in power use lower tention of coaches, officials, and relevant staff. A well- RMs (ie, higher weights or resistance), fewer numbers prepared medical staff also needs to be familiar with of repetitions, higher numbers of sets, and longer recov- medical equipment and examination and treatment fa- ery times between sets. In contrast, training focusing on cilities available. When traveling, game-time review of muscular endurance uses higher RMs (ie, lower weights locations of examination areas, x-ray equipment, ambu- or resistance), much higher number of repetitions, fewer lances, and local hospitals with the hometown medical number of sets and less recovery time in between sets. staff is essential to ensure a quick and efficient response Strength training uses lower RMs than does power and to any athletic injuries. The team physician also needs to endurance training with repetition numbers, set num- have a clear vantage point of the competition and easy bers, and recovery times being similar to that of power access to the athletes competing. Return to competition training. decisions are a part of the game-day responsibilities. Evaluation of concussions, soft-tissue injuries, and eye Sideline Medicine trauma are a few examples where return to play deci- sions are made by the team physician during competi- Sideline medicine is a phrase used to refer to the team tion. Game-day assessment also requires a postcompeti- physician’s approach to handling game-time injuries and tion review of all injuries and illnesses that have illnesses and developing a well-documented and orga- developed and an action plan to ensure necessary nized plan for implementation at the site of competition follow-up. The postcompetition assessment should in- and practices. From a consensus statement released in volve the team physician, trainers, coaches, and relevant 2001 regarding sideline preparedness for the team phy- administrators. sician, the definition of sideline medicine is the identifi- cation of and planning for medical services to promote The postseason evaluation involves a comprehensive the safety of the athlete. Goals are to limit injury and summary of all athletic injuries and illnesses acquired provide medical care at the site of competition. In addi- during competition. It provides a good opportunity to tion, sideline medicine deals with three integrated as- collect data and identify trends during recent competi- pects of athletic competition: preseason planning, game- tion. It also is the time for the team physician to coordi- day operations, and postseason evaluation. nate appropriate follow-up during the off-season. Preseason planning involves the use of the prepartic- Dehydration and Heat Syndromes ipation evaluation to identify potential problems during the season. The team physician must have access to any Dehydration is a loss of all body water caused by de- prior relevant health information before determining el- creased intake or increased losses by evaporation and igibility for participation. Timely completion of the excretion. Prolonged dehydration can lead to tissue dys- preparticipation evaluation is advantageous because it function and eventual hemodynamic collapse as the cir- allows treatment or follow-up to be initiated before culating intravascular volume drops to a critical level sufficient to lower cardiac output. As cardiac output de- creases, so does blood supply to the skin, resulting in de- American Academy of Orthopaedic Surgeons 153

Medical Care of Athletes Orthopaedic Knowledge Update 8 Table 3 | Participants at Risk for Dehydration/Heatstroke Table 4 | Total Body Water/Na+ Deficit Calculations General Calculation of Total Body Water Calculation of Na+ Deficit Poorly acclimated or inexperienced competitors Obese or poorly conditioned Deficit Meq Na+ deficit = 0.6 (wt in kg) Elderly TBW = 0.6 (wt in kg) x ([Na+] − 1) (140 − [Na+]) + (140) x (vol def in Prior history of dehydration/heatstroke L) 140 Medication Usage Antihistamines TBW = total body water; [Na+] = measured serum sodium concentration (mEq/L) Anticholinergics Diuretics Table 5 | Clinical Estimates of Degree of Dehydration Neuroleptics % Dehydration (% wt) Clinical Signs/Symptoms Illness Acute febrile illness 3% to 5% (Mild to Moderate) Orthostasis Recent vomiting or diarrhea 8% to 10% (Moderate to Severe) Thirst Uncontrolled systemic condition (for example, diabetes mellitus or 12% to 15% (Severe) Decreased voiding hypertension) Dry mucous membranes Reduced skin turgor creased heat dissipation and a subsequent rise in core Dry axillary folds body temperature. At extremes of dehydration, sweating mechanisms cease in an attempt to preserve intravascu- All of the above plus: lar volume. This in turn can lead to further increases in Supine hypotension core body temperature, which left unchecked can be fa- Lethargy tal. As little as a 1% drop in total body water has been Tachycardia shown to affect performance. Tachypnea Athletes are particularly at risk for dehydration and Hemodynamic collapse heat illnesses based on the increased demands of com- petition. It is not unusual for competitive athletes to creases in serum sodium levels can produce fatigue, leth- lose as much as 1 to 2 L of sweat per hour with vigor- argy, weakness, confusion, and even hemodynamic col- ous, intense exercise. Athletic participants at risk for de- lapse and death. Salt loading is not recommended hydration and heatstroke are outlined in Table 3. because of the plasma hypertonicity it may produce. Ta- bles 4 through 7 serve as a brief guide for fluid and elec- Aggressive volume replacement is essential during trolyte replacement. exercise. Rehydration also requires electrolyte replace- ment in addition to volume. Although electrolyte con- Thirst is a poor indicator of hydration status in hu- centrations are highly variable, sodium is the cation ex- mans and should not be used alone as a guide for vol- creted in the highest concentration, with lower ume replacement. Measurement of the weight of the concentrations of potassium usually found. Both elec- athlete while unclothed, both before and after competi- trolytes should be replaced, although the necessity is tion, is an excellent way to monitor fluid losses. Hydra- lessened in low-intensity or short-duration exercise and tion before, during, and after exercise should be empha- in those who consume a normal diet. At least 16 oz of sized. fluid supplemented with sodium and potassium should be ingested for every pound of weight lost with exercise. Overuse Injuries Hypotonic salt, or isotonic, carbohydrate supplemented beverages referred to as “sports drinks” are effective re- Overuse injuries refer to musculoskeletal maladies that hydration solutions for palatability and rapid effective develop as a result of environmental, biomechanical, absorption. The presence of increased ingested sodium and equipment factors. They involve one of the follow- and glucose in the intestinal lumen promotes their ing anatomic structures: bursae, tendons, bones, joints, cotransport for absorption in the small intestine. This ac- and ligaments. Overuse injuries are often classified into tive transport creates an osmotic gradient that enhances four stages based on degree of pain. Stage 1 is mild pain net water absorption by passive mechanisms. Plain wa- that develops only after activity. Stage 2 is moderate ter ingestion can be effective for maintaining hydration, pain that occurs during activity but does not restrict or but rehydration after exercise can be slowed by the interfere with performance. Stage 3 is moderate to se- drop in serum osmolality it may create. If allowed to vere pain that interferes with performance. Stage 4 is progress, replacement of sweat losses with hypotonic the most severe form of an overuse injury with signifi- fluid (water) leads to hyponatremia. Significant de- 154 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 14 Medical Care of Athletes Table 6 | Approximate Deficits in Mild to Moderate Table 7 | Guide to Fluid/Electrolyte Replacement Dehydration (5%) Isotonic Dehydration: Serum [Na+]134-145 meq/L Type of Dehydration [Na+] meq/kg [K+] meq/kg Net loss of solute and electrolytes equal to water loss Ex: Common; healthy athlete with inadequate hydration Isotonic 4-5 4-5 Tx: Replace sum of maintenance losses (30-35 mL/kg body weight), [Na+] 134-145 meq/L 0-2 0-2 insensible losses (600-800 mL/day) and estimated water/electrolyte 5-6 5-6 losses over first 24 h; replace 1/2 of volume within first 8 h, rest over Hypertonic next 16 h [Na+] >145 meq/L Hypertonic Dehydration [Na+] >145 meq/L Hypotonic Net loss of water greater than solute [Na+] <134 meq/L Ex: Inadequate hydration with strenuous exercise Tx: Repair TBW deficit over 48 h; rate of reduction of serum Na+ not to *Deficits are doubled for moderate-severe dehydration (10%) exceed 10 meq per/24 h cant pain even at rest. Table 8 outlines common overuse Hypotonic Dehydration [Na+] < 134meq/L injuries. Net loss of solute/electrolytes less than water Ex: Unusual; seen in ultraendurance competitors who overhydrate Medical Care of the Female Athlete Tx: Do not replace more than one half total sodium deficit within first 24 h to avoid central pontine myelinolysis Providing optimal medical care for the female athlete 3% NS used in rare situations with seizure requires an understanding of unique gender-specific is- [Na+] of NS 154 meq/L [Na+] of ½ NS 77 meq/L [Na+] of 3% NS 513 sues. A comprehensive review of these topics is beyond meq/L the scope of this chapter but topics such as exercise in pregnancy, postmenopausal fitness, the female triad (al- Ex = example; Tx = treatment; TBW = total body water; NS = normal saline tered menstrual cycle, eating disorder, abnormal bone metabolism), and athletic injuries seen disproportion- falls should be avoided. Because of decreased venous ately in female competitors will be briefly reviewed. return and a subsequent drop in cardiac output, exercise requiring prolonged, stationary standing after the first Exercise during pregnancy is a vital part of the over- trimester should be avoided. It is also important to re- all health of the mother and fetus. Recent studies have member that physiologic changes may not occur for 6 to shown a decreased morbidity and mortality rate among 10 weeks postpartum and that prepregnancy exercise expectant mothers who established a regular prepartum practices should not be started immediately postpartum. exercise regimen. Normal physiologic changes during pregnancy such as increased weight, increased intravas- The benefits of regular exercise during pregnancy cular volume, increased total body water content, and are numerous and include maintenance of a healthy low back pain as a result of anatomic changes may weight and prevention of excess weight gain, more rapid make exercise more challenging during pregnancy. How- postpartum recovery, improved posture and fewer mus- ever, the intensity and frequency of exercise can be rela- culoskeletal problems such as low back pain. Less pe- tively maintained at prepregnancy levels until late in the ripheral edema, improved sleep quality, improved en- pregnancy. Several modifications should be made. Preg- ergy levels, and an improved overall sense of well-being nant women who exercise should be keenly aware of contribute to a positive experience during the preg- the propensity for thermal dysregulation and should nancy. However, every physician supervising an exercise make extra effort to ensure adequate hydration and program during pregnancy should be aware of absolute provide an exercise environment that is optimal for ade- and relative contraindications to exercise. Absolute con- quate heat exchange. Pregnant women should be aware traindications include preexisting uncontrolled hyper- of increased caloric requirements, roughly 300 to 400 tension, diabetes mellitus, or valvular heart disease. Ob- kcal/day, during pregnancy and adjust diet accordingly. stetrical specific contraindications include preeclampsia Furthermore, because of diminished maternal aerobic or pregnancy-induced hypertension, preterm labor with capacity, the intensity of exercise may need to be modi- the current or previous pregnancy, premature rupture of fied. Exercise to exhaustion, even for elite athletes, is to membranes, second or third trimester bleeding, or in- be discouraged during pregnancy and maternal per- competent cervix. Relative contraindications to exercise ceived exertion should be used as a guide for intensity during pregnancy include history of multiple miscar- levels. Certain specific types of exercises during preg- riages, precipitous labor, breech fetal positioning, and nancy should be avoided. Any type of exercise with a multiple gestations. chance of abdominal contact should be avoided. In gen- eral, complex exercises associated with a propensity for The benefits of exercise in the postmenopausal fe- male are just as clear. A regular aerobic exercise program American Academy of Orthopaedic Surgeons 155

Medical Care of Athletes Orthopaedic Knowledge Update 8 Table 8 | Common Overuse Syndromes Symptoms Treatment Anterior/inferior knee pain and swelling Structures Involved Protective padding, ice, NSAIDs, aspiration, corticosteriod injection Bursae Prepatellar bursitis Rest, ice, PT, local injection Protective padding, ice, NSAIDs, aspiration, Greater trochanteric bursitis Focal, lateral hip pain Olecranon bursitis Elbow pain, swelling corticosteroid injection Ice, NSAIDs, aspiration, corticosteroid injection Pes anserine bursitis Inferior knee pain Tendon PT, rest, NSAIDs, corticosteroid injection Nonlocalized shoulder pain Corticosteroid injection, rest, NSAIDs Rotator cuff tendinitis Localized anterior shoulder pain PT, rest, NSAIDs Biceps tendinitis Knee pain PT, rest, NSAIDs Patellar tendinitis Heel pain PT, rest, NSAIDs Achilles tendinitis Shin pain Corticosteroid injection, PT, rest, NSAIDs Anterior tibialis tendinitis Focal medial/lateral elbow pain Medial/lateral epicondylitis Rest, correction of precipitating factors Bones Localized pain Stress fractures PT, orthoses, splinting, ECSWT Heel, instep pain Insufficiency fractures Apophysitis Ligaments Plantar fasciitis NSAIDs = nonsteroidal anti-inflammatory drugs; PT = physical therapy; ECSWT = extracorporeal shock wave therapy of intermediate intensity most days of the week com- history is often central to the development of menstrual bined with strength and flexibility exercises is essential to irregularities. Menstrual dysfunction is believed to be the health of the postmenopausal athlete. Improvements caused by a lack of a pulsatile release of gonadotropin- in bone density measurements, lipid profiles, body mass releasing hormone from the hypothalamus, which in indices, and sleep quality, all problematic in postmeno- turn leads to diminished release of luteinizing and pausal females, are well established with regular condi- follicle-stimulating hormone from the anterior pituitary tioning. gland. The exact cause of diminished gonadotropin- releasing hormone release is unclear but the role of cir- The female athlete triad consists of abnormal bone culating β-endorphins, cortisol, catecholamines, melato- metabolism, disordered eating, and abnormal menstrual nin, and androgens are all currently under investigation. function. The exact incidence of the disorder is unknown Treatment options include optimizing diet and nutri- but several recent studies suggest that it may be as high tional status, exercise intensity modification, and hor- as 12% of all competitive female athletes. Prevalence mone therapy. rates differ among individual components of the triad ex- isting independently and also differ among individual Eating disorders encompass everything from restric- sports. A prevalence rate of nearly 50% for menstrual tion before competition to frank starvation or binging dysfunction has been reported in some distance runners and purging, referred to as anorexia nervosa and bu- compared with a general prevalence rate of 2% to 5%. limia nervosa, respectively. Signs and symptoms include a characteristically thin body habitus, thin hair and hir- Menstrual dysfunction comprises an entire spectrum sute features, parotid gland hypertrophy, dental caries, of irregularity of menstruation. From delayed onset of subconjunctival hemorrhages, scarring on the dorsum of menarche, defined as onset of menses after age 16 years, the hands, and rectal tears. Treatment depends on the to complete amenorrhea, defined as the absence of 3 to severity of the condition and often involves a multispe- 12 consecutive menstrual periods in the absence of cialty approach including physicians, mental health spe- pregnancy, to oligomenorrhea (irregular, infrequent cialists, and nutritionists. The exact prevalence of eating menses), menstrual dysfunction is common in the fe- disorders among female athletes is unknown. male athlete. Females at risk tend to be younger, nullip- arous, have lower body weights, and are involved with Regular exercise in females leads to increased bone more strenuous, high-intensity sports. A poor dietary density by increasing mechanical stress on bone. A low 156 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 14 Medical Care of Athletes estrogen state seen with delayed or infrequent me- contribute to abnormal patellar tracking. A wider pelvis narche, as is the case with the female triad, leads to poor and increased Q angles have also been proposed as pos- primary bone mass accumulation and the early develop- sible etiologic factors. A propensity for plantar flexion ment of osteoporosis. If allowed to continue, the hy- leading to internal torsion of the tibia and femur accen- poestrogenic state promotes premature bone resorption, tuates lateral patellar tracking and is also believed to be further compounding the problem. Combined with poor a contributing factor. Treatment consists of biomechani- nutrition status, in particular a deficiency in calcium and cal modification and physical therapy modalities. vitamin D, the rate of bone loss can be startling. Several studies have recorded bone densities of female athletes Annotated Bibliography in their 20s that were comparable to those of females in their 60s and 70s. Preparticipation Examination Although not exclusive to female athletes, several Chobanian AV, Bakris GL, Black HR, et al: The Seventh common musculoskeletal athletic injuries are often seen Report of the Joint National Committee on Prevention, in females. Two ligamentous injuries more commonly Detection, Evaluation, and Treatment of High Blood seen in females include ankle sprains (particularly ante- Pressure: The JNC 7 report. JAMA 2003;289:2560-2572. rior talofibular) and anterior cruciate sprains and com- plete tears. Women are particularly vulnerable to ante- This article presents new guidelines for hypertension man- rior cruciate injuries but the exact cause is believed to agement and prevention. be multifactorial. Hormonally-mediated ligamentous hy- perlaxity, decreased ligament size, and a narrowed inter- Carek PJ, Hunter L: The preparticipation physical exam- condylar notch have all been proposed as possible etio- ination for athletics: A critical review of current recom- logic factors. Ankle sprains seem to be more easily mendations. J Med Liban 2001;49:292-297. explained because of the relatively reduced stability of the talus from an inflexible heel cord and the propensity A critical review of current recommendations for the of the female foot to favor a plantar-flexed position. preparticipation examination is presented. Lateral epicondylitis and rotator cuff tendinitis tend Seto CK: Preparticipation cardiovascular screening. Clin to be more prevalent in females, who are believed to be Sports Med 2003;22:23-35. more susceptible to these injuries because of postural differences produced by strength deficiencies and soft- This review article advocates the standardization of the tissue laxity. preparticipation examination. Overuse injuries of bone, particularly stress frac- Conditioning and Preparation tures, are more commonly encountered in females who comprise the classic triad. Healthy female athletes also American Academy of Family Physicians, American are at increased risk because of hormonal factors and Academy of Orthopaedic Surgeons, American College lower muscle to body mass ratios. Spondylolysis, a stress of Sports Medicine, American Orthopaedic Society for fracture to the pars interarticularis of the lumbar spine, Sports Medicine, American Osteopathic Academy for is also seen more frequently in female athletes. Sports Medicine, American Medical Society for Sports Medicine: The team physician and conditioning of ath- Mechanical low back pain is ubiquitous among fe- letes for sports: A consensus statement. Med Sci Sports males; the etiology is usually multifactorial. Two unique Exerc 2001;33:1789-1793. sources of back pain among women are the aforemen- tioned spondylolysis and pelvic instability produced by This article presents a governing body consensus state- sacroiliac joint dysfunction. Hormonal and mechanical ment on conditioning principles for athletes. (particularly the effects of childbirth) factors lead to in- creased laxity among the ligamentous, muscular, and Ebben WP, Blackard DO: Strength and conditioning joint structures that comprise the pelvic ring. This in- practices of National Football League strength and con- creased laxity leads to a propensity for subluxation, par- ditioning coaches. J Strength Cond Res 2001;15:48-58. ticularly anteriorly, that leads to pelvic ring asymmetry and subsequent back pain. A review of conditioning practices in the National Foot- ball League reveals 69% of conditioning coaches follow a pe- Patellofemoral syndrome is another athletic injury riodization model. common in females. The athlete has anterior deep knee pain with varying degrees of swelling and pain that of- Kraemer WJ, Knuttgen HG: Strength training basics: ten is noted to be worsened by walking down steps. The Designing workouts to meet patients goals. Phys Sports increased propensity in females is believed to be the re- Med 2003;31:39-45. sult of increased ligamentous laxity leading to abnormal lateral patellar tracking. A lack of flexibility and weak- Human power production capabilities and differences of ness of the hamstrings and vastus medialis obliquus also physiologic response to varying intensities of exercise are out- lined. American Academy of Orthopaedic Surgeons 157

Medical Care of Athletes Orthopaedic Knowledge Update 8 Sideline Medicine Medical Care of the Female Athlete Mellion M, Walsh WM, Shelton G: The Team Physician’s Brown W: The benefits of physical activity during preg- Handbook, ed 3. Philadelphia, PA, Hanley & Belfus, nancy. J Sci Med Sport 2002;5:37-45. 2001, pp 126-135. Maintenance of a regular exercise program during preg- This book chapter presents an outline for game day man- nancy leads to improved maternal-fetal outcomes. agement for the team physician. Burrows M, Nevill AM, Bird S, Simpson D: Physiologi- Stricker PR: The sports medicine kit: Basics of the bag. cal factors associated with low bone mineral density in Pediatr Ann 2002;31:14-16. female endurance runners. Br J Sports Med 2003;37: 67-71. A review of essential on-site materials for the team physi- cian is presented. This article provides examples of very low bone mineral densities in a sample of 52 female endurance runners. Dehydration and Heat Syndromes Classic Bibliography Burke LM: Nutritional needs for exercise in the heat. Comp Biochem Physiol A Mol Integr Physiol 2001;128: American College of Sports Medicine Position Stand: 735-748. The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and mus- This article reviews the necessity for carbohydrate, vol- cular fitness, and flexibility in healthy adults. Med Sci ume, and electrolyte replacement for vigorous exercise. Sports Exerc 1998;30:975-991. Overuse Injuries Anderson SD, Griesemer BA: Medical concerns in the female athlete. Pediatrics 2000;106:610-613. Maier M, Steinborn M, Schmitz C, et al: Extracorporeal shock-wave therapy for chronic lateral tennis elbow: Buettner CM: The team physician’s bag. Clin Sports Prediction of outcome by imaging. Arch Orthop Trauma Med 1998;17:365-373. Surg 2001;121:379-384. Clapp JF III: Exercise during pregnancy. Clin Sports Forty-two patients were assessed before and after extra- Med 2000;19:273-286. corporeal shock wave therapy; 84% of men and 52% and of women showed a good outcome by MRI at 18 months. Ten- Eichner ER: Treatment of suspected heat illness. Int J dons that were thickened and swollen were most likely to re- Sports Med 1998;19(suppl 2):S150-S153. spond. McFarlane D: Current views on the diagnosis and treat- Grafe MW, Paul GR, Foster TE: The preparticipation ment of upper limb overuse syndromes. Ergonomics sports examination for high school and college athletes. 2002;45:732-735. Clin Sports Med 1997;16:569-587. Treatment remains focused on modification of biomechan- Kurowski K, Chandran S: The preparticipation athletic evaluation. Am Fam Physician 2000;61:2683-2690. ical factors that precipitate these injuries. Panni AS, Biedert RM, Maffulli N, Tartarone M, Roma- Shirreffs SM, Maughan RJ: Rehydration and recovery nini E: Overuse injuries of the extensor mechanism in of fluid balance after exercise. Exerc Sport Sci Rev 2000; athletes. Clin Sports Med 2002;21:483-498. 28:27-32. This article reviews the functional anatomy, pathophysiol- Warren MP, Shantha S: The female athlete. Baillieres Best Prac Res Clin Endocrinol Metab 2000;14:37-53. ogy, and overall management of overuse injuries of the exten- sor mechanism in athletes. 158 American Academy of Orthopaedic Surgeons

Chapter 15 The Polytrauma Patient Hargovind DeWal, MD Robert McLain, MD Introduction and rehabilitation. Psychological support, occupational and physical therapy programs, and multidisciplinary The management of the multiply injured or polytrauma follow-up all contribute to full and timely recovery, and patient requires a multidisciplinary approach integrating improve the likelihood of a satisfactory return to func- organ- and injury-specific treatment protocols. Multiple tion and community life. trauma—injury to multiple organ systems—can directly or indirectly trigger processes that may injure specific These patients often face some likelihood of perma- organs, disrupt metabolic processes, interrupt normal nent impairment and long-term disability. Advances endocrine function, create hemodynamic and physio- have been made in all aspects of polytrauma care, rang- logic instability, and lead to highly lethal systemic dis- ing from improved prehospital care to more aggressive eases and multiple organ failure. By definition, multiple resuscitation and surgical management to aggressive trauma is a life-threatening disorder. physical therapy and spinal cord injury rehabilitation. The treating physician must be conversant in all of these Successful management of the polytrauma patient areas, and keep an eye on all aspects of the patient’s re- requires a team approach and a broad focus. Within a covery if the best outcomes are to be obtained and the few days of injury, the polytrauma patient will be having worst complications avoided. or be at risk for a myriad of potentially serious disor- ders, in addition to their actual, initial injuries. A list of Assessment of the Polytrauma Patient some of these disorders is found in Table 1. An orderly, structured assessment of the polytrauma pa- The concept of a “damage control” approach to or- tient has been shown to improve care and reduce the thopaedic injuries is discussed in the recent literature likelihood of missed injuries. Patients with multiple inju- and should be observed to minimize the risk of com- ries typically arrive in the emergency department under pounding systemic injury through added surgical injury. the care of another health care provider, most often a A dedicated intensivist, skilled anesthesia staff, trauma trained emergency medical technician, who will have as- and orthopaedic trauma surgeons, nutritional support sessed the patient in the field, established intravenous services, infectious disease specialists, and plastic and re- access, and may have intubated the patient to restore or constructive surgeons may all play a role in the care of a maintain the airway. They will provide important infor- single patient. It is imperative that all of these individu- mation on the mechanism of injury, the patient’s condi- als buy into the principles of trauma management and tion at the time of first contact, and evidence of neuro- communicate well with the other members of the team. logic function, respiratory status, and responsiveness at the time of initial resuscitation. Their initial observa- The environment for patient care must support the tions may provide important perspective as to the pa- level of care required. Access to diagnostic studies, inter- tient’s improvement or deterioration when compared ventions, line care, and respiratory support must be im- with the initial assessment in the emergency depart- mediate and available around the clock. Nursing staff ment. must understand the fragility of the patient and recog- nize that changes in respiratory or circulatory parame- Once the patient arrives in the emergency depart- ters may require immediate attention and response. ment, resuscitation and a primary assessment begin si- Staff must also be familiar with protocols for mobiliza- multaneously. These two processes are interdependent tion, deep venous thrombosis prophylaxis, and pulmo- in that the purpose of the primary assessment is to find nary and bowel care. the causes of hemodynamic instability, respiratory im- pairment, and circulatory collapse at the same time oth- After the patient’s condition is stabilized, attention ers on the team are trying to restore those functions to nutrition, infection control, pulmonary function, and skin care play an often underappreciated role in healing American Academy of Orthopaedic Surgeons 159