Orthopaedic Knowledge Home Study by R. Alexander

Adult Spinal Deformity Orthopaedic Knowledge Update 8 Figure 2 Preoperative PA (A) and lateral (B) weight-bearing radiographs of an adult patient with scoliosis who was treated with staged anterior and posterior fusion with posterior fixation to the pelvis using iliac screw fixation. Postoperative PA (C) and lateral (D) weight-bearing radiographs of the same patient. adults with good bone stock, extension of the fusion to result is associated with increasing patient comorbidi- include the involved segments and reinstrumentation ties, thoracic pseudarthrosis, and adjacent segment are sufficient treatment. However, in patients with a breakdown caudad to the fusion. To restore lumbar lor- fixed deformity with coronal or sagittal imbalance, espe- dosis in patients with multiple pseudarthrosis or fusions cially in the presence of osteopenia, a combined ap- that are not intact to the sacrum, a combined approach proach is preferable. is preferable. This may be performed as a first-stage pos- terior procedure with osteotomies and instrumentation Disk degeneration may develop below a fusion and to the sacrum followed by anterior interbody fusion require salvage reconstruction. If there is isolated spinal with structural allograft or vice versa (Figure 4). For se- stenosis, decompression alone is usually sufficient. If the vere, rigid, unbalanced deformity, a spinal shortening patient has a vertebral insufficiency fracture below the procedure such as a vertebral body resection is neces- fusion, extension of the fusion and instrumentation is sary. necessary. Postoperatively, adult patients are mobilized within Loss of lumbar lordosis occurs gradually with aging. 24 to 48 hours depending on pain tolerance and overall Iatrogenic loss of lumbar lordosis is typically caused by general condition. Then the patient is given intravenous the use of distraction implants across the lumbar spine. narcotic medication via a patient-controlled pump until Some patients who undergo salvage procedures experi- oral pain medication is tolerated. The use of postopera- ence loss of lumbar lordosis secondary to sagittal plane tive anti-inflammatory agents such as ketorolac is con- imbalance. In these patients, the primary goal of the in- traindicated because the fusion rate is adversely af- dex procedure was coronal plane correction. These pa- fected. Perioperative antibiotics can be continued for 36 tients are best treated with a combined surgical proce- to 48 hours. Antiembolic stockings and sequential com- dure. For patients with a solid arthrodesis, a pedicle pression devices are used to minimize the incidence of subtraction osteotomy with vertebral body decancella- venous thrombosis until the patients are ambulatory. tion using the posterior approach and rigid internal fixa- Anticoagulation is not performed routinely, but it may tion can provide up to 30° to 40° of sagittal plane cor- be considered in high-risk patients and in patients with rection. This procedure is particularly useful in patients a preexisting history of thromboembolic disease. In pa- with combined anterior and posterior fusion who still tients with a history of pulmonary embolism, a vena have flat-back deformity (Figure 3). A poorer clinical 570 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 46 Adult Spinal Deformity Figure 3 PA (A) and lateral (B) full-length weight-bearing radiographs of a 56-year-old woman with lumbar flat-back syndrome following lumbar decompression and instru- mented fusion. The patient had severe sagittal plane decompensation and recurrent spinal stenosis with back pain and bilateral buttock and leg radiculopathy. Note that the lateral radiograph demonstrates evidence of severe sagittal plane decompensation. Postoperative PA (C) and lateral (D) full-length weight-bearing radiographs of the same patient after revision laminectomy and transpedicular wedge resection at L3 with restoration of sagittal balance. cava filter may be considered before surgical interven- source of bone graft. It is well known that pulmonary tion. The patients are fitted with a lightweight plastic function can deteriorate after thoracotomy and thoraco- orthosis within 5 to 7 days of surgery and are instructed plasty. These procedures should be used with extreme to wear the brace full time, except when in bed and for caution in patients with severely compromised pulmo- hygiene. nary function. Unlike adolescents, adult patients with scoliosis do not recover lost pulmonary function, even at Controversial Issues in Managing Adult 2-year follow-up. Patients With Scoliosis Results and Complications The absolute indications for combined surgery versus posterior fusion and instrumentation alone are unclear. The results of surgical correction of spinal deformity in Combined surgery allows for better correction and rees- adults have improved significantly over the past decade. tablishment of physiologic lumbar lordosis through the The rate of complications ranges from 12% to 23% of use of anterior structural grafting, and it increases the patients. Pseudarthrosis rates have varied between 5% probability of successful fusion. In patients with com- to 27% of patients, with higher rates of pseudarthrosis plex deformities involving the lumbar spine in which fu- occurring after revision surgery and after using nonseg- sion across the lumbosacral junction is necessary to mental posterior implants in distraction mode. Pain in achieve spinal balance, combined procedures are prefer- these patients is seldom totally alleviated by surgical able because 15% to 20% of patients who undergo pos- correction. However, reports of residual pain after com- terior instrumentation and fusion have pseudarthrosis, plex spinal reconstructive surgery vary between 5% and even when the stiffer third-generation instrumentation 25% of patients. Approximately 61% of patients report systems are used. improved sleep patterns after surgical treatment, and 57% are able to return to work. Mortality remains low Thoracoplasty is a useful adjunct in treating patients in patients who undergo complex spinal reconstructive with spinal deformity. Thoracoplasty reduces rib promi- surgery, but it is not insignificant (< 1% to 5% of pa- nence by 71% compared with only a 17% reduction in tients). Overall, patient outcomes as assessed by the control subjects. Rib resection also provides a good American Academy of Orthopaedic Surgeons 571

Adult Spinal Deformity Orthopaedic Knowledge Update 8 Figure 4 Preoperative PA (A) and lateral (B) full-length weight-bearing radiographs of a 50-year-old woman with flat-back syndrome and pseudarthrosis after posterior lumbar interbody fusion with threaded cages at L4-5 and instrumented posterolateral fusion at L5-S1. Note that the lateral radiograph shows evidence of significant sagittal plane decompensation. Postoperative PA (C) and lateral (D) radiographs of the same patient after multiple level Smith-Peterson osteotomies and instrumented fusion and repair of pseudarthrosis. Note that the postoperative lateral radiograph shows evidence of restoration of lumbar lordosis. Medical Outcomes Study Short Form 36-Item Health of the curve, and preexisting atherosclerosis. Thus, Survey (SF-36) and the American Academy of Ortho- proper postoperative volume support and vigilance are paedic Surgeons’ Modems Instrument are significantly essential. Loss of vision as a complication of spinal re- associated with radiographic correction of the lumbar constructive surgery is a rare but often permanent event lordosis to greater than 25° and coronal plumb align- that can occur as the result of ischemic optic neuropa- ment to within 2.5 cm. Patients with primary degenera- thy, retinal artery occlusion, or cerebral ischemia. The tive lumbar scoliosis as well as those who have had long incidence of pulmonary embolism varies from 1% to fusions to L4, L5, or the sacrum have improved gait pa- 20% of patients, depending on the series. Air embolism rameters (both speed and endurance) after spinal de- can occur in patients with patent foramen ovale. How- compression and fusion, with restoration of coronal and ever, only a few isolated instances of this complication sagittal balance. Outcomes assessment in this challeng- have been reported. Flail chest can occur with overag- ing group of patients is necessary to determine the im- gressive thoracoplasty, especially in revision situations. pact of deformity correction on the patients’ quality of life and daily function. The Modified Scoliosis Research Infection is a relatively rare event in patients who Society Outcomes Instrument for Adult Deformity, the undergo surgery for spinal deformities; it occurs in be- Oswestry Disability Index, and the SF-36 are the most tween 1% and 8% of patients. In addition, infection af- commonly used validated outcomes questionnaires for ter anterior surgery alone occurs in about 1% of pa- adult patients undergoing spinal deformity surgery. tients. However, the sequelae of deep postoperative infection are substantial, with up to 38% to 64% of pa- Neurologic injury occurs in fewer than 1% to 5% of tients having pseudarthrosis at 37-month follow-up. De- patients who undergo surgical treatment for spinal de- layed infections can occur more than 2 years postopera- formities. Significant risk factors for major intraopera- tively, typically with low virulent organisms. tive neurologic deficits include combined anterior and posterior surgery and hyperkyphosis. Delayed postoper- If coronal and sagittal balance is achieved and main- ative paraplegia is another devastating complication af- tained with a solid fusion, the outcomes are generally ter extensive spinal reconstructive surgery, and it can oc- excellent. Pulmonary improvement after correction of cur several hours after the completion of the procedure. spinal deformity is unlikely to occur in the adult and the This phenomenon has been attributed to ischemia of use of thoracoplasty may actually reduce pulmonary the spinal cord from postoperative hypovolemia, me- function. The correction of curvature varies from 30% chanical tension of spinal blood vessels on the concavity to 60% and depends on the nature and flexibility of the patient’s preoperative curve and the technique used for 572 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 46 Adult Spinal Deformity correction. Despite these relatively modest gains, satis- Suk S, Kim WJ, Lee SM, et al: Thoracic pedicle screw faction with surgical correction is generally high and can fixation in spinal deformities: Are they really safe? reach up to 90% of patients. Spine 2001;26:2049-2057. Annotated Bibliography In this study, 4,604 thoracic pedicle screws were placed in the treatment of adult patients with spinal deformity; the au- Prevalence and Natural History thors report an overall rate of screw malposition of 1.5%. Most thoracic pedicle screws were placed inferior or lateral to Kovacs FM, Gestoso M, Gil del Real MT, Lopez J, Mu- the pedicle. Screw-related complications occurred in 0.8% of fraggi N, Mendez JI: Risks factors for non-specific low patients. Deformity correction was 69.9% for patients with back pain in school children and their parents: A popu- coronal plane deformities and 47° for those with kyphosis. lation based study. Pain 2003;103:259-268. Voos K, Boachie-Adeji O, Rawlins BA: Multiple verte- In this European study involving 16,394 adolescents and bral osteotomies in the treatment of rigid adult spinal their parents, the lifetime prevalence of low back pain was deformities. Spine 2001;26:526-533. 50.9% for males and 69.3% for females. Scoliosis was an inde- pendent risk factor. This retrospective chart and radiographic review of 27 consecutive adult patients with spinal deformity demonstrated Schwab F, Dubey A, Pagala M, et al: Adult scoliosis: A the efficacy of multiple vertebral osteotomies in the manage- health assessment analysis by SF-36. Spine 2003;28:602- ment of rigid adult spinal deformities. The authors reported 606. that the average scoliosis correction for these patients was 40% and the average correction in sagittal balance was 6.5 cm. This prospective self-assessment of a consecutive series of adult patients with scoliosis showed that scoliosis has a signifi- Degenerative Lumbar Scoliosis cant impact on patients’ perception of health. Berven S, Hu SS, Deverin V: Lumbar end plate osteot- Weinstein SL, Dolan LA, Spratt KF, Peterson KK, omy in adult patients with scoliosis. Clin Orthop 2003; Spoonamore MJ, Ponseti IV: Health and function of pa- 411:70-76. tients with untreated idiopathic scoliosis: A 50-year nat- ural history study. JAMA 2003;289:559-567. The authors of this study discuss a technique of end plate osteotomy and concave osteophyte excision in adults with This prospective cohort analysis of 117 untreated patients fixed lumbosacral fractional curves that avoids extension of with idiopathic scoliosis followed over a 50-year span showed fusion to the sacrum. a greater incidence for back pain and cosmetic deformity in patients with scoliosis compared with 62 control patients. Pa- Bridwell KH, Edwards CC II, Lenke LG: The pros and tients with thoracic curves greater than 80° were more likely cons to saving the L5-S1 motion segment in a long scoli- to report shortness of breath, suggesting a deterioration of osis fusion construct. Spine 2003;28:S234-S242. pulmonary function in this subgroup. This article presents a review of the literature and the au- Patient Assessment thors’ personal experiences concerning the advantages and disadvantages of extending a long scoliosis fusion to the Davis BJ, Gadgil A, Trivedi J: Ahmed el NB: Traction ra- sacrum. The subject is controversial and no good studies exist diography performed under general anesthetic: A new that definitively answer the question. technique for assessing idiopathic scoliosis curves. Spine 2004;29:2466-2470. Tribus CB: Degenerative lumbar scoliosis: Evaluation and management. J Am Acad Orthop Surg 2003;11:174- Traction radiographs taken with the patient under general 183. anesthesia allow a better assessment of curve flexibility than standard supine bending radiographs. This finding may obviate This article presents a review of evaluation and treatment the need for anterior release and fusion in select patients. of degenerative scoliosis. Comparison to fulcrum bending radiographs was not per- formed in this study. Salvage Procedures in Adult Patients Treatment Berven SH, Deviren V, Smith JA, Hu SH, Bradford DS: Management of fixed sagittal plane deformity: Outcome Ali R, Boachie-Adjei O, Rawlins BA: Functional and ra- of combined anterior and posterior surgery. Spine 2003; diographic outcomes after surgery for adult scoliosis us- 28:1710-1715. ing third-generation instrumentation techniques. Spine 2003;28:1163-1169. Twenty-five patients with fixed sagittal imbalances were treated with combined anterior-posterior fusion. This study This retrospective radiographic and chart review of 28 pa- showed that combined surgery is an effective method to treat tients with adult scoliosis treated with primary corrective sur- fixed sagittal deformity. Patients with preoperative hypolordo- gery showed significant clinical and radiographic improve- sis (relative flat-back syndrome) who had good restoration of ments using third-generation spinal implants. lumbar lordosis and sagittal plane balance had the best out- comes. American Academy of Orthopaedic Surgeons 573

Adult Spinal Deformity Orthopaedic Knowledge Update 8 Bridwell K, Lewis S, Lenke LG, et al: Pedicle subtrac- evaluated for severity of back pain and overall function. Func- tion osteotomy for the treatment of fixed sagittal imbal- tional scores for patients with scoliosis were lower than those ance. J Bone Joint Surg Am 2003;85-A:454-463. for the control group. Frequency and severity of back pain scores were lower in patients treated with fusion than in the In this study, 27 consecutive patients with fixed sagittal im- patients with untreated scoliosis. balance and treated with pedicle subtraction osteotomy were evaluated using Oswestry and Modified Scoliosis Research So- Classic Bibliography ciety Outcomes Instrument for Adult Deformity question- naires. The authors report that pedicle subtraction osteotomy Albert TJ, Purtill J, Mesa J, McIntosh T, Balderston RA: is an effective procedure in this group of patients, with signifi- Health outcome assessment before and after adult de- cant improvements in overall Oswestry scores and decreased formity surgery: A prospective study. Spine 1995;20: pain scores. A poorer clinical result was associated with in- 2002-2005. creasing patient comorbidities, pseudarthrosis in the thoracic spine, and subsequent breakdown caudad to the fusion. Ascani E, Bartolozzi P, Logroscino CA, et al: Natural history of untreated idiopathic scoliosis after skeletal Results and Complications maturity. Spine 1986;11:784-789. Eck KR, Bridwell KH, Ungacta FF, et al: Complications Boachie-Adjei O, Bradford DS: Vertebral column resec- and results of long adult deformity fusions down to L4, tion and arthrodesis for complex spinal deformities. L5, and the sacrum. Spine 2001;26:E182-E192. J Spinal Disord 1991;4:193-202. The authors of this study report the outcomes and compli- Bradford DS, Tribus CB: Vertebral column resection for cation rates of patients treated surgically for adult lumbar the treatment of rigid coronal decompensation. Spine scoliosis at an average 5-year follow-up (minimum 2-year 1997;22:1590-1599. follow-up). They report that patients with fusions short of the sacrum who developed distal spinal degeneration had worse Collis DK, Ponseti IV: Long-term follow-up of patients outcomes that those patients with fusion to the sacrum. with idiopathic scoliosis not treated surgically. J Bone Joint Surg Am 1969;51:425-445. Emami A, Deverin V, Berven S, et al: Outcome and complications of long fusions to the sacrum in adult spi- Dickson JH, Mirkovic S, Noble PC, Nalty T, Erwin WD: nal deformity. Spine 2002;27:776-786. Results of operative treatment of idiopathic scoliosis in adults. J Bone Joint Surg Am 1995;77:513-523. This is a retrospective study of 54 adult patients with spi- nal deformities who were treated with different techniques to Goldberg MS, Mayo NE, Poitras B, Scott S, Hanley J: achieve long fusion to the sacrum. All patients had combined The Ste-Justine Adolescent Idiopathic Scoliosis Cohort anterior and posterior reconstruction with a minimum 2-year Study: Part II. Perception of health, self and body im- follow-up. The authors report a 34% pseudarthrosis rate in pa- age, and participation in physical activities. Spine 1994; tients who had Luque-Galveston fixation compared with bi- 19:1562-1572. cortical sacral screw and iliac screw fixation. Hu SS, Fontaine F, Kelly B, Bradford DS: Nutritional Lapp MA, Bridwell KH, Lenke LG, et al: Long-term depletion in staged spinal reconstructive surgery: The ef- complications in adult deformity patients having com- fect of total parenteral nutrition. Spine 1998;23:1401- bined surgery: A comparison of primary to revision pa- 1405. tients. Spine 2001;26:973-983. Hu SS, Holly EA, Lele C, et al: Patient outcomes after This outcomes analysis compares the complication rates of spinal reconstructive surgery in patients > or = 40 years primary surgery and revision surgery in 44 consecutive pa- of age. J Spinal Disord 1996;9:460-469. tients who underwent combined procedures for correction of adult spinal deformity with a minimum 2-year follow-up. The Jackson RP, Simmons EH, Stripinis D: Incidence and se- results demonstrated similar rates of minor complications verity of back pain in adult idiopathic scoliosis. Spine (22% to 23% of patients). The primary surgery group had a 1983;8:749-756. higher rate of major complications and a significantly higher rate of pseudarthrosis compared with the revision surgery Lenke LG, Bridwell KH, Blanke K, Baldus C: Analysis group. of pulmonary function and chest cage dimension changes after thoracoplasty in idiopathic scoliosis. Spine Parsch D, Gaertner V, Brocai DR, Carstens C: The effect 1995;20:1343-1350. of spinal fusion on the long-term outcome of idiopathic scoliosis: A case control study. J Bone Joint Surg Br Nachemson A: Adult scoliosis and back pain. Spine 2001;83:1133-1136. 1979;4:513-517. In this study, 68 patients with scoliosis (34 treated and 34 untreated) compared with age- and sex-matched controls were 574 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 46 Adult Spinal Deformity Thomasen E: Vertebral osteotomy for correction of ky- Weinstein SL, Ponseti IV: Curve progression in idio- phosis in ankylosing spondylitis. Clin Orthop 1985;194: pathic scoliosis. J Bone Joint Surg Am 1983;65:447-455. 142-152. Vanderpool DW, James JI, Wynne-Davies R: Scoliosis in the elderly. J Bone Joint Surg Am 1969;51:446-455. American Academy of Orthopaedic Surgeons 575



Chapter 47 Spinal Infections Eric S. Wieser, MD Jeffrey C. Wang, MD Introduction injection). Contiguous spread of infection to the spine is most commonly associated with retropharyngeal and Historically, patients with spinal infections experienced retroperitoneal abscesses. Any condition that causes a poor results with high morbidity and mortality rates. transient bacteremia may ultimately lead to hematoge- Medical innovations over the past several decades, in- nous vertebral osteomyelitis. cluding the improvement of antimicrobial chemother- apy, powerful laboratory and imaging techniques, and The pathogenesis of spinal infection in children dif- advancements in surgical techniques have significantly fers significantly from that of adults because of the dif- improved the outcomes of patients with spinal infec- ferences in the vascular anatomy of the vertebrae and tions. Earlier detection of vertebral osteomyelitis and intervertebral disks. Isolated diskitis primarily occurs in diskitis through increased clinician awareness and the children and vertebral osteomyelitis is common in adult- use of advanced imaging modalities are crucial in limit- hood. In children, vascularity extends through the carti- ing or avoiding complications associated with progres- laginous growth plate into the nucleus pulposus, allow- sive spinal infection such as epidural abscess, structural ing direct deposition of bacterial emboli into the center deformities, chronic osteomyelitis, paralysis, sepsis, and of the disk. However, in adults, blood vessels reach only death. to the anulus fibrosus, limiting deposition of bacteria to the vertebral body metaphysis and end plate. Pyogenic Vertebral Osteomyelitis Hematogenous seeding of the vertebrae is described Epidemiology and Pathogenesis by two major theories. First, Batson described retro- grade flow through the valveless vertebral venous The demographic features of patients with vertebral os- plexus within the vertebral metaphyseal region where teomyelitis have changed over the past years because of bacterial seeding could occur under increased abdomi- medical advances and the aging of the population. Ver- nal pressure. This theory was refuted with another the- tebral osteomyelitis affects approximately 2% to 7% of ory that proposed that bacteria can become wedged in all patients with pyogenic osteomyelitis in developed the end metaphyseal arteriole loops. Infection spreads countries. Despite an overall decrease in the incidence after the microorganisms are lodged in the low-flow vas- of tuberculous spondylitis, the incidence of pyogenic cular loops in the metaphysis and at the end plates. Af- vertebral osteomyelitis appears to have increased. This ter the infection is established near the end plate of one increase is probably related to the growth in the elderly vertebral body, it can penetrate through the end plate and immunocompromised populations, increases in the into the adjoining disk. The avascular disk material is number of invasive medical procedures, and an increase destroyed by bacterial enzymes, allowing the infection in intravenous drug use. Risk factors for pyogenic verte- to spread to the adjacent vertebral body. Posterior spi- bral osteomyelitis that have recently been described in nal arteries have abundant anastomoses about the disk, the literature are listed in Table 1. which probably contributes to the spread of the infec- tion from one level to the next. Several theories exist regarding the mechanism of bacterial seeding of the spine. Pyogenic vertebral osteo- Staphylococcus aureus remains the most common or- myelitis is a bacterial infection with several possible ganism cultured from pyogenic vertebral osteomyelitis sources including direct inoculation, contiguous spread and is found in 50% to 65% of culture positive cases. from local infection, or hematogenous seeding. Direct S aureus accounts for more than 80% of pediatric spinal inoculation can occur after penetrating trauma, open infections. There also has been an increase in the num- spinal fracture, and following percutaneous or open spi- ber of gram-negative bacillus spinal infections over the nal procedures (such as diskography, diskectomy, past decade. The genitourinary tract, respiratory tract, chemonucleolysis, or any other diagnostic or therapeutic and soft-tissue infections are often the source of these American Academy of Orthopaedic Surgeons 577

Spinal Infections Orthopaedic Knowledge Update 8 Table 1 | Risk Factors for Pyogenic Vertebral Osteomyelitis Table 2 | Risk Factors for Neurologic Deterioration With Vertebral Osteomyelitis Male sex Intravenous drug abuse Diabetes mellitus Diabetes mellitus Rheumatoid arthritis Urinary tract infection Systemic corticosteroid use Respiratory tract infection Advanced age Recent genitourinary procedure Cephalad level of infection (high thoracic or cervical) Previous spinal procedure Staphylococcal infection Morbid obesity Alcohol abuse to paralysis include diabetes, rheumatoid arthritis, sys- Human immunodeficiency virus/acquired immunodeficiency syndrome temic steroid use, increasing age, Staphylococcus infec- Malignancy tion, and a more cephalad level of infection. The risk Corticosteroid use factors for neurologic deterioration with vertebral os- Penetrating trauma teomyelitis are summarized in Table 2. gram-negative infections. Escherichia coli, Pseudomo- Laboratory Evaluation nas, and Proteus infections often occur after genitouri- nary infections or procedures. Pseudomonas infections Laboratory studies often support the diagnosis of infec- are also often seen in intravenous drug users. From in- tion but remain nonspecific. The white blood cell count testinal flora, Salmonella can cause vertebral osteomy- is elevated in about 50% of patients. The erythrocyte elitis in children with sickle cell disease. Enterococcus, sedimentation rate (ESR) is a much more sensitive test Propionobacterium acnes, Streptococcus viridans, Sta- and is elevated in more than 90% of patients; however, phylococcus epidermidis and diphtheroids have all been its specificity for infection is poor. All patients should causative organisms of pyogenic vertebral osteomyelitis. have a C-reactive protein (CRP) test, which is slightly more sensitive and specific than the ESR. The CRP is Clinical Characteristics also elevated sooner than the ESR. Both tests are help- ful in following the course of treatment of the infection. The clinical presentation of vertebral osteomyelitis is However, each of these markers of inflammation will be highly variable depending on the location of infection, elevated following an invasive procedure without any the virulence of the organism, and the immunocompe- infection present. A substantial decrease in the ESR and tency of the host. Pyogenic infections of the spine occur CRP suggests an adequate response to treatment. 50% of the time in the lumbar spine followed by ap- proximately 40% in the thoracic spine, and only about The definitive diagnosis of spinal pyogenic osteomy- 10% of the time in the cervical spine. Fever and consti- elitis requires identification of the organism through ei- tutional symptoms are present in approximately 50% of ther a positive blood culture with confirmatory clinical the affected population. Weight loss is common but and imaging features or from a biopsy and culture of rarely recognized by the patient. the infected site. Blood and urine cultures should be done on all patients before the administration of any Approximately 90% of patients with pyogenic infec- antibiotics. Blood cultures have been reported to be tions will have back or neck pain that is often quite se- positive in 25% to 60% of patients. A positive urine cul- vere and insidious in onset, which accounts for the fre- ture does not necessarily confirm the diagnosis because quent delay in diagnosis. Because the pain is often a different organism may be identified at the time of present at rest and at night, there is concern for the dif- vertebral biopsy. In general, it is appropriate to delay ferential diagnosis of potential malignancy. Muscle antibiotics until all cultures have been obtained; how- spasms often are associated with neck or back pain. Tor- ever, if the patient is septic or critically ill, antibiotics ticollis and dysphagia often accompany fever as the only should be initiated immediately. symptoms of cervical infection. Lumbar infection can lead to loss of lumbar lordosis, hamstring tightness, hip Biopsy of the infected site is often necessary to iden- flexion contracture, or a positive straight leg raising test. tify the infecting organism and exclude other potential etiologies. Spinal biopsies may be performed percutane- Neurologic deficits are present in about 10% of pa- ously using fluoroscopy or more accurately with CT. A tients secondary to nerve root or spinal cord compres- second closed biopsy is recommended if the diagnosis is sion, especially with cervical or thoracic level disease. not confirmed after the first attempt. CT-guided biopsy Patients may report radicular pain, motor nerve root provides the best results, with positive cultures in 68% paresis, and paralysis. Risk factors predisposing patients to 86% of patients. Open biopsy is indicated when nee- dle biopsy fails to identify the organism. Minimally inva- 578 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 47 Spinal Infections sive techniques such as endoscopic or thoracoscopic ap- dality of choice for the diagnosis of spinal infections. proaches may be considered when appropriate. Open MRI has a sensitivity of 96% and specificity of 93% for biopsies yield positive results in more than 80% of pa- the diagnosis of vertebral osteomyelitis. On T1-weighted tients. All biopsy specimens should be sent for Gram images, the affected vertebral body and disk both show stain, acid-fast and potassium hydroxide staining, and low signal intensity with loss of distinction at their mar- cultures (including aerobic, anaerobic, mycobacterium, gins, secondary to the marrow edema and decreased fat fungi, and atypical mycobacterium). All cultures should content. In contrast, on T2-weighted images, the verte- be retained to allow for the growth of mycobacterium bral body has increased signal intensity secondary to the and low virulence organisms. Especially with low- increase in water content associated with the inflamma- virulence and indolent bacteria, polymerase chain reac- tion and edema. On gadolinium-enhanced T1-weighted tion has facilitated earlier identification of the infecting images, abscess collections show abnormal rim enhance- organism. Caution is needed to avoid cross contamina- ment, whereas areas of active inflammation in the verte- tion with the use of polymerase chain reaction. Speci- bral body and disk are enhanced. mens also should routinely be sent for histologic analy- sis to rule out malignancy. Treatment Malnutrition is often coincident with spinal infec- The goals for treatment of spinal infections include es- tion; therefore, an evaluation of the patient’s nutritional tablishing a diagnosis and identifying the organism, status is crucial in determining appropriate nutritional eliminating the infection, preventing or improving neu- therapy as a part of treatment. Laboratory measures rologic involvement, and maintaining spinal stability. As such as serum albumin level less than 3 g/dL, a serum with other illnesses, nutritional repletion and optimiza- transferrin level of less than 150 ug/dL, and an absolute tion of medical comorbidities are crucial to eradication lymphocyte count less than 800/mL suggest severe mal- of the infection. nutrition, which should be addressed as part of the treatment of the vertebral osteomyelitis. Treatment of vertebral osteomyelitis usually entails a trial of nonsurgical treatment with spinal immobiliza- Radiographic Evaluation tion, early ambulation, proper nutritional support, and intravenous antibiotics followed by oral antibiotics (spe- Imaging studies lag behind the clinical course of pyo- cific for the organism cultured). If the offending organ- genic vertebral osteomyelitis but are vital in localizing ism cannot be identified even after biopsy, empiric and determining the extent of involvement of the infec- parenteral antibiotics should be administered. tion and for assessing the response to treatment. Plain Parenteral antibiotics are generally recommended for 4 radiographs can show subtle paravertebral soft-tissue to 6 weeks to prevent high failure rates of nonsurgical swelling in the first few days of infection. After 7 to 10 treatment in patients with pyogenic infections. Patients days, disk space narrowing can be observed. After sev- are converted to oral antibiotics after signs of clinical eral weeks, radiographs show frank erosion and destruc- improvement, normalization of the ESR and CRP lev- tion of the vertebral end plates and anterior vertebrae els, or resolution of the infection on imaging studies. with extension into the central portion of the vertebral body. The disk space continues to collapse and vertebral Immobilization of the affected area helps prevent compression and paraspinal mass are noted. CT scans deformity and aids in pain relief. The application of a show paravertebral soft-tissue masses and, most impor- rigid contact brace is effective in the lumbar region. A tantly, define the extent of bony involvement of the in- rigid cervicothoracic orthosis or halo is often required fection. CT scans show the anatomy in detail and can be for cervical osteomyelitis. Serial laboratory tests (CRP used to guide percutaneous drainage or biopsy and for and ESR) should be followed to monitor response to preoperative planning. treatment. Approximately 75% of patients respond to nonsurgical treatment with resolution of pain and often Radionuclide studies also are useful in evaluating spontaneous fusion. spinal infections and can be positive before the develop- ment of radiographic changes. Technetium Tc 99m bone Surgical intervention is warranted to obtain a tissue scintigraphy is more than 90% sensitive, but it lacks diagnosis after failed percutaneous needle biopsies, to specificity for infection. Scans that combine technetium address neurologic deficit secondary to compression, to Tc 99m with gallium 67 increase both the sensitivity and treat spinal instability or significant deformity, to drain specificity for identifying infection. Indium 111-labeled infectious foci causing sepsis, or for failure of nonsurgi- leukocyte scans are not recommended for vertebral os- cal medical treatment alone. Nonsurgical treatment is teomyelitis because of poor sensitivity (17%). Gallium often unsuccessful in elderly and immunocompromised scans may be used to follow treatment response because patients, who then require surgical management. The lo- they begin to normalize during the recovery phase. MRI cation of the infection and the goals of the surgery dic- with gadolinium contrast has become the imaging mo- tate the intervention performed. If the surgery is in- tended to obtain a specimen for diagnosis, then an American Academy of Orthopaedic Surgeons 579

Spinal Infections Orthopaedic Knowledge Update 8 Figure 1 Imaging studies of an 80-year-old man with a 3-month history of increasing neck pain and recent onset of fever. A, A lateral radiograph shows collapse of the C5 vertebral body and end plate erosion of C4 and C6 with segmental kyphosis secondary to pyogenic vertebral osteomyelitis. The patient was treated with anterior débridement and corpectomy of C5, with partial corpectomy of C4 and C6, and with allograft fibula strut graft. This treatment was followed by posterior stabilization with C3-7 lateral mass fixation and iliac crest bone graft. Postoperative lateral (B) and AP (C) radiographs. anterior or posterior transpedicular biopsy (possibly us- Spinal Epidural Abscess ing minimally invasive techniques) is appropriate. Epidemiology and Pathogenesis The anterior approach is preferred for the treatment of vertebral osteomyelitis because it permits débride- There has been an increased incidence of spinal epidu- ment of the infected bone and tissue, decompression of ral abscess over the past decade. The reported incidence the neural elements, drainage of an epidural abscess, of the disease, however, is only 1.2 per 10,000 hospital and stabilization of adjacent spinal segments. Posterior admissions. Patients are most often age 60 years or old- infections are exceedingly rare but are amenable to a er; men and women are equally affected. Factors that posterior approach for débridement. Cultures should al- contribute to the relative increased incidence of epidu- ways be obtained intraoperatively and thorough irriga- ral abscess include an increase in intravenous drug use, tion and débridement of all infected and necrotic tissue an increase in the number of immunocompromised is required. The anterior débridement inevitably leaves hosts secondary to malignancy or human immunodefi- a bony void, which often requires stabilization of the an- ciency virus and/or acquired immunodeficiency syn- terior column with interbody arthrodesis and posterior drome, and an increase in the number of invasive spinal stabilization (Figure 1). If a kyphotic deformity is operations and procedures (such as epidural anesthesia, present, it can be reduced and maintained with appro- spinal injections, and diskography). priate interbody graft placement. Autogenous tricortical iliac crest, rib, or fibular strut grafting (vascularized or A spinal epidural abscess is a collection of pus or in- nonvascularized) has proven safe and effective in the flammatory granulation tissue between the dura mater presence of acute infection. Freeze-dried allografts are and the surrounding epidural adipose tissue.The presence being used with successful results, but autogenous of a spinal epidural abscess is typically associated with a sources are preferred because of better incorporation. coexistent vertebral osteomyelitis or diskitis. Contiguous In the presence of a severe kyphotic deformity or when spread of pathogens from adjacent disk or bone is the a multilevel anterior construct is required, the addition most common route of infection. However, hematogenous of posterior fusion with instrumentation is recom- seeding of bacteria into the epidural space occurs rarely. mended to adequately stabilize the spine (Figure 2). The Recently, studies have documented spinal epidural ab- procedure can be performed concomitantly or in a scess after direct inoculation during spinal procedures. staged manner. A recent study showed superior defor- The causative organism remains S aureus in more than mity correction with anterior titanium mesh cages filled 60% of patients. Gram-negative rods account for approx- with autograft followed by posterior instrumentation. imately 18% of infections. Pseudomonas is commonly found in intravenous drug users. Epidural abscesses are found in the cervical spine in approximately 14% of patients, and most are found an- 580 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 47 Spinal Infections Figure 2 Imaging studies of a 60-year-old man who had worsening back pain for 2 months. A, Lateral radiograph of the lumbar spine shows complete loss of disk space at L3-4 and end plate erosions of the L3 and L4 vertebrae. B, T2-fat suppressed MRI scan of the lumbar spine shows L3-4 diskitis and associated pyogenic vertebral osteomyelitis. C, The patient was treated with anterior débridement with interbody fusion using allograft strut followed by posterior fusion with instrumentation. teriorly. The majority of spinal epidural abscesses are Patients with an acute epidural abscess usually have found in the thoracic (51%) and lumbar (35%) spine. more systemic illness than those patients with vertebral Most of these infections are posterior unless contiguous osteomyelitis. Laboratory evaluation shows leukocytosis with vertebral osteomyelitis. Three to four spinal seg- (mean, 22,000 cells/mm3), elevated ESR (mean, 86.3 mm ments are usually involved, but the entire spinal column in 1 hour), and an elevated CRP. Plain radiographs are is at risk. usually normal unless contiguous vertebral osteomyelitis or diskitis has been present long enough for the radio- Initially, there is an inflammatory reaction in the epi- graphic findings to be positive. CT scans have a poor dural fat that progresses to suppuration, necrosis, and fi- sensitivity for epidural abscess. MRI with gadolinium brosis in the epidural space. The pathogenesis of the contrast is the imaging modality of choice for the diag- neurologic manifestations is related either to direct nosis and evaluation of spinal epidural abscess. The ex- compression of the neural elements or to compromise act location and extent of the abscess, the amount of of the intrinsic circulation of the spinal cord. neurologic compression, and the presence and severity of contiguous infection can all be evaluated with MRI. Clinical Characteristics and Diagnosis Pus in the epidural space will enhance with gadolinium, whereas the cerebrospinal fluid will show low signal in- Intractable back or neck pain is the most common tensity on T1-weighted images. Biopsy of the adjacent symptom in patients with a spinal epidural abscess. disk, vertebral body, or surrounding tissue provides the However, the clinical presentation of a patient with an definitive diagnosis of spinal epidural abscess and iden- epidural abscess can be highly variable; this variability tification of the offending organism. leads to frequent misdiagnosis on initial presentation. Most patients with an acute spinal epidural abscess have Treatment and Prognosis fever, back pain, and spinal tenderness; however, these outward signs may be absent if the disease is chronic. If Historically, the presence of spinal epidural abscess has treatment is not initiated early, the back pain is followed been regarded as a medical and surgical emergency. The by radicular pain, weakness, paralysis, and even frank objectives of treatment of epidural abscesses are eradi- sepsis. The immune status of the host and the virulence cation of infection, prevention or improvement of neu- of the offending pathogen dictate the timing and sever- rologic sequelae, and preservation of spinal stability. ity of the progression of the infection. If the abscess Nonsurgical treatment of a spinal epidural abscess is penetrates the dura, a subdural abscess or meningitis only indicated in patients who are neurologically stable may occur. or are unsuitable surgical candidates because of medical American Academy of Orthopaedic Surgeons 581

Spinal Infections Orthopaedic Knowledge Update 8 Figure 3 Imaging studies fof a 65-year- old man who developed cervical pyogenic osteomyelitis with associated epidural ab- scess and neurologic deficits with con- comitant lumbar diskitis. A, Sagittal T2- weighted MRI scan of the cervical spine shows increased signal intensity through- out the C6 and C7 vertebral bodies with associated diskitis and epidural abscess causing anterior mass effect on the spinal cord. B, Sagittal T2-weighted image of lumbar spine shows signal enhancement of L2-3 disk and end plates consistent with diskitis and early pyogenic vertebral osteomyelitis. comorbidities. A recent study showed that nonsurgical with spinal epidural abscess included younger age, less treatment of spinal epidural abscess is possible if no than 50% thecal sac compression, lumbosacral location, neurologic compromise has occurred. A new or progres- the presence of pustular abscesses as opposed to granu- sive neurologic deterioration warrants immediate lation tissue, and shorter duration of symptoms. change from nonsurgical to surgical treatment. Nonpyogenic Vertebral Osteomyelitis Surgical intervention is the current treatment for most patients with spinal epidural abscess. The surgical Nonpyogenic or granulomatous infections of the spine approach and technique depend on the location and ex- may be caused by fungi, atypical bacteria, or spiro- tent of the infection. Because the location is usually pos- chetes. These infections are grouped together because, terior, a decompressive laminectomy over the involved although the lesions resulting from these causes are not levels generally is the treatment of choice. Wide decom- common, when they occur they have a similar clinical pression with facetectomy is not usually required for ad- and histologic presentation. Most spinal infections in pa- equate débridement and should be avoided because iat- tients in the United States are pyogenic; however, with rogenic spinal instability may result. If anterior the increased number of immunocompromised hosts, vertebral osteomyelitis or diskitis is present, combined more nonpyogenic infections have emerged in the past anterior and posterior débridement may be necessary decade. The pathophysiology of granulomatous spinal (Figure 3). Reconstruction of the anterior column with infection differs from that of pyogenic infections. By far, structural graft or instrumentation may be required if the most common granulomatous disease of the spine is significant bony destruction has occurred. Posterior fu- caused by Mycobacterium tuberculosis. Tuberculous sion with instrumentation often is preferred when acute spondylitis (Pott’s disease) is the most extensively re- infection is present after anterior débridement. searched disease in this group of infections. Parenteral antibiotics are chosen based on the culture and sensitivity results, and are continued for 2 to 4 Epidemiology and Pathogenesis weeks after adequate surgical débridement. If vertebral osteomyelitis is present, parenteral antibiotics should be Although tuberculosis (TB) is endemic in many devel- administered for at least 6 weeks. oping countries, it was nearly eradicated in the United States. Nevertheless, there has been a resurgence of TB Spinal epidural abscesses continue to have signifi- infection in the past decade, with the disease often oc- cant morbidity and mortality as a result of diagnostic curring in immunocompromised patients and with resis- delay. Recent literature reports that early diagnosis re- tant strains of the organism. The human immunodefi- mains the most essential factor in preventing devastat- ciency virus and acquired immunodeficiency syndrome ing outcomes. A recent retrospective study found that epidemic is a major cause of the increase in TB infec- factors associated with improved outcome of patients tion in the United States. Ten percent of patients in- 582 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 47 Spinal Infections fected with TB will develop musculoskeletal infection, tional symptoms of chronic illness including intermittent but 50% of these patients will have spinal involvement. fever, malaise, night sweats, and weight loss. Neurologic deficit is present in 10% to 47% of patients with Pott’s Hematogenous seeding from the respiratory or geni- disease. Deformity at the time of diagnosis is more com- tourinary tract is the usual mode of spread of infection mon in TB infection than in pyogenic spinal infection. to the spine. Local spread by direct extension is also possible. Most active cases of spinal TB in adults are ac- Laboratory studies are helpful but nonspecific. The tually reactivations of quiescent lesions from previous white blood cell count often is not elevated. The ESR is infection. usually elevated but may be normal in up to 25% of pa- tients. Purified protein derivative skin tests typically are The three major types of spinal involvement of ver- positive, which suggests either active or previous dis- tebral TB describe the pattern of bony involvement. The ease. False negative results are possible because of an- most common form is the peridiskal type, which begins ergy, which could result from any condition that com- with infection in the metaphyseal area that spreads un- promises host immunity. A chest radiograph should be der the anterior longitudinal ligament and later involves obtained in all patients to rule out active lung involve- the adjacent vertebral bodies. In contrast to pyogenic in- ment. fection, the disk is relatively resistant to infection and is often preserved until late in the infection process de- Plain radiographs are useful in diagnosis, but they spite extensive bony destruction. With the anterior type, will vary in appearance depending on the pathologic infection spreads beneath the anterior longitudinal liga- type and chronicity of the infection. After several weeks ment and may involve several vertebral levels, causing of infection, radiographs show vertebral end plate lu- anterior erosions on the involved vertebral bodies. Cen- cency and loss of cortical margins. Soft-tissue swelling tral type infections often are mistaken for tumors be- and expansion across two to three spinal segments fol- cause they remain isolated to one vertebra and often low. Eventually, the classic pattern of disk space destruc- cause collapse and deformity. Isolated posterior element tion with lucency and compression of adjacent vertebral involvement has been described but is exceedingly rare. bodies is seen, followed by further collapse into a ky- photic deformity. The pathologic findings in tuberculous spondylitis differ in several respects from pyogenic vertebral osteo- Nuclear medicine studies with a combination of myelitis. The disk is relatively resistant to infection by technetium and gallium nuclear scans have been shown TB. In addition, the development of the infection takes to have the highest sensitivity for detecting infection. a longer period of time, and more deformity is typically CT scans are beneficial in evaluating the extent of bony observed at the time of presentation. Large paraspinal destruction and in surgical planning. However, the pre- abscesses are more common with tuberculous infections. ferred imaging study for the diagnosis of tuberculous The thoracic spine is the most common location for spi- and fungal infections remains MRI with gadolinium nal TB followed by lumbar involvement. The cervical contrast. MRI helps to differentiate metastatic disease spine is rarely involved. from vertebral osteomyelitis; the lack of disk space in- volvement is seen with MRI only with metastatic dis- Other etiologies of granulomatous infection are also ease. increasing in incidence with the increasing number of immunocompromised hosts. Atypical bacteria such as Definitive diagnosis requires a positive biopsy with Actinomyces israelii, Nocardia asteroids, and Brucella culture of the organism. Studies have shown that CT- species also cause chronic granulomatous infection. Tre- guided biopsy with cultures and staining allows identifi- ponema pallidum, the organism responsible for syphilis, cation of the organism. Mycobacteria are acid-fast ba- causes gummatous lesions in the spine, which are syphi- cilli and may take up to 10 weeks to grow in culture. litic granulomas representing the local reaction of the Polymerase chain reaction has been used for fast identi- tissues to the organism and its products. Fungal infec- fication of mycobacteria with a sensitivity of 95% and tions of the spine are uncommon and often have a sig- accuracy of 93%. nificant delay in diagnosis. Coccidioides immitis, Blasto- myces dermatitidis, Cryptococcus neoformans, Candida Treatment species, and Aspergillosis are all responsible for fungal infections of the spine. In a recent study of patients with Nonpyogenic vertebral osteomyelitis is usually treated fungal spinal infections, the Candida species were the with chemotherapy directed at the offending pathogen. most common fungal pathogens. Additionally, an external immobilization device may be used for pain control and prevention of deformity. Tu- Clinical Presentation and Evaluation berculous spondylitis is treated with isoniazid, rifampin, and pyrazinamide for 9 to 18 months depending on re- The onset of symptoms with tuberculous spondylitis is sponse to treatment. Ethambutol or streptomycin is usu- typically more insidious than with a pyogenic infection. ally added to the regimen for at least part of the treat- Patients usually report pain in the spine and constitu- ment. It is recommended that an infectious disease American Academy of Orthopaedic Surgeons 583

Spinal Infections Orthopaedic Knowledge Update 8 Figure 4 Imaging studies of a 48-year-old woman who presented with a 6-month history of severe low back pain. A, Plain radiograph shows evidence of chronic pyogenic vertebral osteomyelitis of L4-5 with sclerosis and apparent autofusion consistent with the duration of symptoms. B, Sagittal T2-weighted MRI shows continued enhancement of L4 and L5 vertebral bodies as well as diskitis at L5-S1. AP (C) and lateral (D) postoperative radiographs of the patient who was treated with anterior débridement and interbody fusion of L4-L5 and L5-S1, with femoral ring allografts followed by posterior fusion with instrumentation. consultation be done in conjunction with the chemo- gest that anterior instrumentation reduces kyphotic de- therapy regimen because of varying regional resistance formity without increasing the risk of disease recur- patterns. Amphotericin B and ketoconazole provide the rence. In patients with neurologic deficit, earlier mainstay for the treatment of most fungal infections. débridement led to a faster and better neurologic recov- Brucellosis is typically treated with tetracycline and ery. There is a direct correlation between duration of streptomycin. Nocardia infections are treated with sul- preoperative symptoms and neurologic recovery. fonamides, whereas actinomycosis is still treated with penicillin. Postoperative Spinal Infections The surgical indications for treatment of nonpyo- An increase in the incidence of postoperative infections genic spinal infections are neurologic deficits, failure of has been documented in the past decade. Postoperative response to nonsurgical treatment after 3 to 6 months, infections result from inoculation during the index pro- the need for tissue for diagnosis, spinal instability, pro- cedure or by hematogenous seeding of the surgical site. gressive kyphotic deformity, and/or recurrence of the Lumbar diskectomy performed with the use of prophy- disease. Surgical options include anterior débridement lactic antibiotics carries a 0.7% incidence of infection. and strut graft alone or with posterior instrumentation The use of the operating microscope for diskectomy in- and fusion (Figure 4), or posterior débridement without creases that rate to 1.4%. Studies have shown that lum- anterior surgery done only for isolated posterior dis- bar fusion with instrumentation has an estimated inci- ease. If a laminectomy were performed for isolated pos- dence of postoperative infection of 6%. A recent terior arch disease or posterior epidural abscess, then a retrospective review showed a wound infection rate of supplemental fusion would be recommended. Anterior 10% in trauma patients who underwent fusion for tho- débridement and reconstruction at the site of pathology racolumbar fractures. The authors concluded that the has shown the best long-term neurologic and structural overall risk of infection is higher in the trauma patient results. Graft choice is dependent on surgeon prefer- than in the elective surgery population and that those ence. Autogenous and allograft strut grafts are accept- patients with complete neurologic deficit are at a able with good results. A recent study showed that ante- greater risk of infection. Another recent study showed rior spinal instrumentation with structural allograft that late pain at the surgical site appearing 12 to fibula could be used after proper anterior débridement 20 months after scoliosis surgery with posterior instru- of tuberculous spondylitis with a 96% fusion rate and mentation is most often attributable to a subacute low- no recurrence of infection. Patients did not require ex- grade implant infection. ternal support in the postoperative period. Another study, using fresh frozen femoral allografts and stabiliza- Prophylactic antibiotics have been shown in several tion with a single-rod construct after anterior débride- studies to significantly reduce the incidence of postoper- ment, showed excellent results with incorporation of the ative infections. Prophylactic antibiotics should reach allografts between 12 and 18 months. These studies sug- peak concentrations quickly and cover S aureus and S epidermidis. Cefazolin, a first-generation cephalospo- 584 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 47 Spinal Infections Table 3 | Risk Factors for Developing Postoperative tibiotics taken for 6 weeks are required for patients with Infections deep infection, bony involvement, or retained hardware. Advanced age Annotated Bibliography Obesity Diabetes mellitus Pyogenic Vertebral Osteomyelitis Smoking Immunocompromised host Hee HT, Majd ME, Holt RT, Pienkowski D: Better Length of preoperative hospitalization treatment of vertebral osteomyelitis using posterior sta- Myelodysplasia bilization and titanium mesh cages. J Spinal Disord Tech Revision surgery 2002;15:149-156. Increased surgical time Spinal instrumentation The authors evaluated the efficacy of using titanium mesh Bone graft cages anteriorly and posterior instrumentation after anterior Methylmethacrylate débridement in the surgical treatment of vertebral osteomyeli- Arthrodesis tis. Patients treated with cages had better sagittal and coronal Trauma correction. rin, has good Staphylococcus coverage and should be ad- Schimmer RC, Jeanneret C, Nunley PD, Jeanneret B: ministered at least 20 minutes before surgery. To prevent Osteomyelitis of the cervical spine: A potentially dra- resistance, vancomycin should be used for prophylaxis matic disease. J Spinal Disord Tech 2002;15:110-117. only in patients at high risk for methicillin-resistant S au- reus. Risk factors for postoperative spinal infections are A retrospective review of 15 patients treated for osteomy- listed in Table 3. elitis of the cervical spine is presented. Good results were achieved by early and aggressive surgical intervention. Clinical presentation of postoperative infections de- pends on timing and the depth of the infection. In the Spinal Epidural Abscess immediate postoperative period, patients with superfi- cial wound infections may have pain, fever, tenderness, Tang HJ, Lin HJ, Liu YC, Li CM: Spinal epidural ab- erythema, and drainage from the incision site. Diagnosis scess: Experience with 46 patients and evaluation of of deep wound infections is more difficult because com- prognostic factors. J Infect 2002;45:76-81. plete onset may be delayed, with only constitutional symptoms and a well healed surgical incision. Labora- This article reviewed 46 patients treated for spinal epidu- tory values including leukocyte count, ESR, and CRP ral abscess with emphasis on defining clinical characteristics, are often elevated. The acute phase reactants are nor- treatment options, and evaluation of prognostic factors. mally elevated in the immediate postoperative period. The ESR remains elevated for up to 6 weeks, whereas Nonpyogenic Vertebral Osteomyelitis the CRP normalizes in approximately 2 weeks. S aureus is cultured in about 60% of wound infections. Frazier DD, Campbell DR, Garvey TA, Wiesel S, Bohl- man HH, Eismont FJ: Fungal infections of the spine: Aggressive surgical intervention is generally recom- Report of eleven patients with long-term follow-up. mended for postoperative infections. Administration of J Bone Joint Surg Am 2001;83:560-565. antibiotics should be delayed until intraoperative super- ficial and deep cultures are obtained. Aggressive dé- This article presents a retrospective review of 11 patients bridement followed by copious irrigation is recom- treated for spinal osteomyelitis caused by a fungus. The au- mended. Wound closure over closed suction drains is thors describe delay in treatment and diagnosis as important required unless the wound is packed open for repeat factors in poor outcomes. They recommend performing fungal débridements. Recent studies advocate the use of antibi- cultures whenever a spinal infection is suspected. otic beads, especially in the presence of hardware. Un- less the fusion is solid, most surgeons retain the instru- Govender S: The outcome of allografts and anterior in- mentation and bone graft. If significant soft-tissue strumentation in spinal tuberculosis. Clin Orthop 2002; necrosis or dead space is present, plastic surgical tech- 398:50-59. niques including musculocutaneous flaps may be neces- sary. For patients with soft-tissue and wound infections, This article presents a review of 41 patients with neuro- 10 to 14 days of antibiotics are sufficient. Parenteral an- logic deficits caused by spinal TB who were treated with radi- cal anterior decompression with reconstruction of the anterior column with fresh-frozen femoral ring allograft and stabilized with a single-rod screw instrumentation construct. Ozdemir HM, Us AK, Ogun T: The role of anterior spi- nal instrumentation and allograft fibula for the treat- ment of pott disease. Spine 2003;28:474-479. The authors retrospectively reviewed 28 patients with mul- tilevel spinal TB who had anterior débridement, decompres- sion, and fusion with anterior spinal instrumentation and fibu- American Academy of Orthopaedic Surgeons 585

Spinal Infections Orthopaedic Knowledge Update 8 lar allograft. A 96% fusion rate with no graft complications tumors and infections with magnetic resonance imaging. was recorded. Spine 1991;16(suppl 8):S334-S338. Postoperative Spinal Infections Carragee EJ: Pyogenic vertebral osteomyelitis. J Bone Joint Surg Am 1997;79:874-880. Kothari NA, Pelchovitz DJ, Meyer JS: Imaging of mus- culoskeletal infections. Radiol Clin North Am 2001;39: Currier BL, Eismont FJ: Infections of the spine, in 653-671. Herkowitz HN, Garfin GR, Balderston RA, Eismont FJ, Ball GR, Wiesel SW (eds): The Spine. Philadelphia, PA, This article reviews the epidemiology, pathophysiology, WB Saunders, 1999, pp 1207-1258. and the clinical and imaging presentations of musculosketetal infections of all types. Discussion is presented on the imaging Eismont FJ, Bohlman HH, Soni PL, Goldberg VM, Free- characteristics of plain radiographs, CT scans, MRI, and nu- hafer AA: Pyogenic and fungal vertebral osteomyelitis clear studies for various spinal infections. with paralysis. J Bone Joint Surg Am 1983;65:19-29. Rechtine GR, Bono PL, Cahill D, Bolesta MJ, Chrin Emery SE, Chan DP, Woodward HR: Treatment of he- AM: Postoperative wound infection after instrumenta- matogenous pyogenic vertebral osteomyelitis with ante- tion of thoracic and lumbar fractures. J Orthop Trauma rior debridement and primary bone grafting. Spine 1989; 2001;15:566-569. 14:284-291. Twelve of 117 patients (10%) with thoracolumbar frac- Heggeness MH, Esses SI, Errico T, et al: Late infection tures who had surgical intervention developed postoperative of spinal instrumentation by hematogenous seeding. wound infections. The authors observed that the overall risk of Spine 1993;18:492-496. infection is higher in trauma patients especially those with neurologic deficit. Tay BK, Deckey J, Hu SS: Spinal Infections. J Am Acad Moon MS: Tuberculosis of the spine: Controversies and Orthop Surg 2002;10:188-197. a new challenge. Spine 1997;22:1791-1797. A thorough review of the literature and a concise descrip- Rezai AR, Woo HH, Errico TJ, Cooper PR: Contempo- tion of current methods of diagnosis, laboratory assessment, rary management of spinal osteomyelitis. Neurosurgery imaging, and treatment of spinal infections in both children 1999;44:1018-1026. and adults are presented. Vaccaro AR, Harris BM, Madigan L: Spinal infections, Thalgott JS, Cotler HB, Sasso RC, LaRocca H, Gardner pyogenic osteomyelitis, and epidural abscess, in Vaccaro V: Postoperative infections in spinal implants classifica- A, Betz R, Zeidman S (eds): Principles and Practice of tion and analysis: A multicenter study. Spine 1991;16: Spine Surgery. Philadelphia, PA, Mosby, 2003, pp 165- 981-984. 174. Wheeler D, Keiser P, Rigamont D, Keay S: Medical This chapter presents a current comprehensive review of management of spinal epidural abscesses: Case report and review. Clin Infect Dis 1992;15:22-27. spinal infections. Classic Bibliography Yilmaz C, Selek HY, Gurkan I, Erdemli B, Korkusu Z: Anterior instrumentation for the treatment of spinal tu- An HS, Vaccaro AR, Dolinskas CA, Colter JM, Balder- berculosis. J Bone Joint Surg Am 1999;81:1261-1267. ston RA, Bauerle WB: Differentiation between spinal 586 American Academy of Orthopaedic Surgeons

Chapter 48 Tumors of the Spine Gurvinder S. Deol, MD Rex Haydon, MD, PhD Frank M. Phillips, MD Introduction represent perhaps the most sensitive test for osteoid os- teoma, a CT scan is the most specific. Treatment of this Primary and metastatic tumors of the spine encompass a disorder includes both medical and surgical options. wide spectrum of disease processes requiring many dif- Pain associated with osteoid osteoma, as a rule, re- ferent treatment algorithms. The treatment of spinal tu- sponds to treatment with NSAIDs. Given the usually mors has evolved over the course of the past decade self-limited nature of osteoid osteoma, NSAIDs and ob- with the advent of improved diagnosis, staging, and non- servation are the initial treatment. In patients in whom surgical and surgical treatment. NSAIDs are either not tolerated or are contraindicated or in patients whose osteoid osteoma is associated with Primary Tumors progressive scoliotic deformities, more aggressive thera- pies can be considered. Excision of the lesions results in Primary tumors of the spine account for 2% to 5% of reliable pain relief, and most associated scoliotic defor- all spinal neoplasms, with metastatic tumors accounting mities improve. Good short-term results with percutane- for most spinal tumors. Within the group of primary tu- ous radiofrequency ablation of osteoid osteoma have mors, benign tumors are far more common than malig- been reported. nant tumors. Benign Tumors Osteoblastoma Histologically, osteoblastomas are often indistinguishable Osteoid Osteoma from osteoid osteomas except for their size, but the clin- Osteoid osteomas are probably the most common pri- ical features and natural history of these two disorders mary benign vertebral tumors, and they are usually di- have notable differences. Spine involvement is even more agnosed during the first three decades of life, with a commonly associated with osteoblastoma, accounting for peak incidence at age 15 years. Ten percent to 25% of approximately 40% of instances; lesions typically localize all osteoid osteomas occur in the spine, and nearly 70% to the posterior elements in 55% of patients. The most of painful juvenile scoliotic deformities are associated common presenting symptom in patients with osteoblas- with osteoid osteomas that typically occur at the apex of toma is focal pain, which is less responsive to NSAIDs the concavity of the curve as a cortically based nidus of than the pain associated with osteoid osteoma.The pain is osteoid-producing cells surrounded by a dense halo of more typically activity-related. Cortical expansion can re- sclerosis, which may be the only radiographic sign at di- sult in impingement of neural elements. Painful scoliotic agnosis. Histologically, the lesion manifests as a nidus of deformities can also occur in the setting of osteoblasto- highly vascular osteoid-producing spindle cells sur- ma; however, this is much less common than with osteoid rounded by dense sclerotic bone. Pain is the most com- osteoma. Osteoblastomas are more readily detected on mon presenting symptom and is characteristically worse plain radiographs because of their larger size (> 2 cm), and at night and relieved by treatment with nonsteroidal their propensity to cause cortical expansion. The internal anti-inflammatory drugs (NSAIDs). On plain radio- characteristics of osteoblastomas can be variable, but os- graphs, the overlying bony structures often obscure the sification is the predominant pattern, which is consistent appearance of osteoid osteoma, making additional im- with its osteoblastic origin. Osteoblastoma is a slowly pro- aging studies necessary. The most sensitive study for os- gressive lesion that does not normally respond to conser- teoid osteoma is the bone scan, which targets the rapid vative management. Surgical resection of the lesion is bone turnover, a hallmark of this lesion. Increased up- therefore indicated; however, local recurrences occur in take of technetium Tc 99m occurs in the area of the le- 10% to 15% of patients, and the recurrence rate can be as sion, often surrounded by a zone of diminished uptake, high as 50% in patients with high-grade subtypes of os- creating a distinctive target sign. Although bone scans American Academy of Orthopaedic Surgeons 587

Tumors of the Spine Orthopaedic Knowledge Update 8 teoblastoma. Debate exists regarding the adequacy of ited number of patients with this disorder, it is difficult curettage in the treatment of osteoblastoma, and it has yet to define a clear predilection for either the anterior or to be determined whether marginal resection results in a posterior spinal elements; however, it has been reported lower risk of recurrence. Surgical treatment (simple curet- that most spinal chondroblastomas occur in the poste- tage or resection) should be planned based on the loca- rior elements. Chondroblastomas usually contain nu- tion of the lesion, concomitant symptoms, and risk of mor- merous osteoclast-like giant cells; matrix calcification, bidity. Malignant transformation of osteoblastomas has when present, often has a distinctive chicken-wire ap- been documented. pearance, which is a histologic hallmark of this lesion. Cellular atypia can vary from moderate to high, which is Giant Cell Tumor believed to reflect the spectrum of behavior of chondro- Giant cell tumors can range in behavior from slowly blastoma from slowly progressive local growth to ag- growing, relatively innocuous tumors to locally aggres- gressive local growth and metastatic spread. Treatment sive tumors that metastasize. The spine is a relatively of these lesions consists predominantly of curettage or common site for giant cell tumors, comprising between excision; however, it is not clear whether this treatment 5% and 10% of all instances of giant cell tumor. Unlike is effective in the spine, given the limited number of pa- their appendicular counterparts, however, there is often tients with spinal chondroblastomas. The recurrence rate a significant delay between the onset of symptoms in for chondroblastomas of the spine is likewise unclear. the spine and the diagnosis. Pain and radiculopathy are the most common presenting symptoms, and they have Osteochondroma often been present for several months before the pa- Spinal osteochondromas account for less than 10% of tient’s initial contact with a physician. Spinal giant cell all osteochondromas. They usually arise from the poste- tumors are most commonly diagnosed during the third rior elements. Typically, they are slow-growing masses and fourth decades of life, and they occur at a slightly and rarely cause mechanical or compressive symptoms. more frequent rate in women. Within the axial skeleton, They are therefore largely observed unless they begin to the sacrum is the most common region affected, and le- cause problems such as persistent pain or radiculopathy. sions are typically found in the vertebral body. Plain If this occurs, these tumors can be resected. The rate of films generally demonstrate a well-demarcated, radiolu- recurrence after resection in adults is low, and in skele- cent lesion with a variable amount of cortical expansion tally immature patients it is imperative to resect the car- and local remodeling. Even in the most aggressive in- tilage cap to prevent recurrence. Malignant transforma- stances of giant cell tumor, a thin shell of cortical bone tion to chondrosarcomas has been reported and occurs will usually remain at the periphery of the lesion, which more commonly in patients with multiple hereditary ex- helps distinguish it from a malignant bone tumor. Giant ostoses. These lesions tend to be low grade and respond cell tumors involving the spine are typically treated by well to local wide resection. curettage. En bloc surgical resection is considered to be the optimal treatment of this disorder and appears to Langerhans Cell Histiocytosis reduce the rate of local recurrence. In the spine, the This condition, more commonly known as eosinophilic proximity of vital structures to the lesion, as well as the granuloma, represents a usually benign, self-limiting considerable morbidity associated with this approach process that usually causes focal areas of well- has limited the use of en bloc resections. Spinal giant demarcated bone resorption, which in the spine gives cell tumors have a considerably poorer prognosis than rise to the classic vertebra plana sign. The underlying those in the appendicular skeleton, with recurrence etiology of this disorder is unknown, and it usually af- rates reaching almost 80% in grade III giant cell tumors. fects individuals during the first and second decades of Furthermore, metastasis occurs in just under 10% of pa- life, with a 2:1 predilection for males. The spine is in- tients. volved in 10% to 15% of patients, but the condition more commonly affects the skull and flat bones of the Chondroblastoma pelvis, rib cage, and shoulder. Although most instances Chondroblastoma of the spine is extremely rare, and of this disorder are self-limiting and resolve on their published articles regarding spinal chondroblastoma are own, surgical intervention may be indicated in patients mostly limited to case reports. Nonetheless, most pa- with progressive kyphosis or neurologic symptoms. Low- tients with this disorder have been diagnosed during the dose radiation therapy has also shown to be effective in second or third decade of life. Radiographic evaluation patients who are not amenable to resection. It is impor- of spinal chondroblastomas generally reveals a well- tant to be aware of two systemic disease processes asso- demarcated radiolucent lesion. Evidence of internal ma- ciated with eosinophilic granuloma: Hand-Schüller- trix calcification may be apparent on plain radiographs Christian disease and Letterer-Siwe disease. Both of or CT scans; however, this is not a universal finding in these disease processes involve multifocal lesions along all patients with chondroblastoma. Because of the lim- with other systemic manifestations. 588 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 48 Tumors of the Spine Aneurysmal Bone Cyst a variety of histologic subtypes. Treatment and progno- Aneurysmal bone cysts involve the spine in 10% to 30% sis are, therefore, dependent on appropriate histologic of patients, and they are most commonly found in the diagnosis. There is a bimodal distribution in the age of posterior elements of the thoracolumbar spine. They can presentation of patients with osteosarcomas involving occur at any age but are most common during the first the spine; a young patient population (age 10 to 25 two decades of life. Unique to aneurysmal bone cysts is years) typically has the more classic type of osteosar- their ability to involve multilevel adjacent spinal seg- coma, whereas patients older than 50 years typically ments. Radiographically, aneurysmal bone cysts cause have secondary osteosarcomas. When viewed collec- cortical expansion and thinning, and have a characteris- tively, osteosarcoma of the spine has a generally poorer tic “bubbly” appearance created by multiple cavernous prognosis and occurs in older age groups when com- chambers. MRI is needed to detect smaller aneurysmal pared with appendicular osteosarcoma. The primary le- bone cysts, and fluid/fluid levels, which represent old ar- sion can be either radiolucent or radiodense, with prom- eas of hemorrhage, are almost pathognomonic for aneu- inent periosteal reaction and usually soft-tissue rysmal bone cysts. Treatment includes curettage, wide lo- extension. The internal characteristics of the lesion dem- cal excision, embolization, and sometimes radiation. The onstrate ossification consistent with the degree of os- rate of local recurrence has been estimated to be be- teoid production. Numerous histologic subtypes of os- tween 15% and 30% of patients; recurrence is treated teosarcoma exist that are designated by location by repeat curettage. (central, parosteal, and periosteal), grade (low versus high), predominant cell type (osteoblastic, chondroblas- Hemangioma tic, and fibroblastic), or etiology (radiation-induced, and Hemangiomas of the spine represent the most common Paget’s sarcoma). With the exception of low-grade le- tumor of the spine and are usually identified as an inci- sions such as parosteal osteosarcomas, patients with os- dental finding. At autopsy, 11% of individuals are re- teosarcoma of the spine receive preoperative chemo- ported to have hemangiomas. These occur as singular le- therapy followed by surgical resection and usually sions in approximately two thirds of individuals, and the adjuvant therapy. As with other malignant lesions of the lesions are characterized radiographically by vertical spine, wide resections or even marginal resections are trabecular striations resembling a honeycomb that most often not possible, making radiation therapy and adju- commonly involve the vertebral body, with the thoracic vant chemotherapy necessary to treat the residual dis- spine being the most commonly affected. Plain radio- ease. Estimation of the outcome in patients with os- graphs can be sufficient to diagnose those lesions that teosarcoma of the spine has been hampered by its involve greater than 30% to 40% of the vertebral body; relative rarity. Metastasis at diagnosis, large size, sacral however, CT or MRI may be more helpful in detecting location, and intralesional resections are associated with the presence of more subtle lesions. Neurologic symp- adverse outcomes. toms may occur as a result of neural compression caused by cortical expansion or soft-tissue extension be- Chondrosarcoma yond the vertebral body. Hemangiomas are radiosensi- After chordomas, chondrosarcoma is the most common tive, and low-dose radiation has been shown to be effec- primary malignant tumor of bone in the spine, account- tive as a treatment of symptomatic lesions, as has ing for approximately 7% to 12% of all spine tumors. embolization via angiography. In those instances where Chondrosarcomas occur more commonly in men than pathologic fracture or deformity results in instability or women and later in life, with the average age at diagno- neurologic compromise, surgical resection and stabiliza- sis being 45 years. Chondrosarcoma can vary consid- tion may be indicated. Vertebral cement augmentation erably in its behavior, and it is generally described ac- procedures (vertebroplasty and kyphoplasty) have also cording to grades I through III, with each grade been successfully used to treat hemangiomas. corresponding to an increasing tendency for metastasis and, therefore, a poorer prognosis. Plain films typically Malignant Tumors demonstrate a centrally based destructive lesion with calcification. In patients with low-grade chondrosar- Osteosarcoma coma, the lesion can cause scalloping of the bony cortex Osteosarcoma of the spine carries with it an especially or cortical expansion. In patients with high-grade chon- bleak prognosis. Osteosarcoma of the spine accounts for drosarcoma, the tumor can erode through the cortex approximately 2% of all osteosarcomas throughout the and form a large extraosseous mass, also containing dif- body, and 3% to 14% of malignant tumors involving the fuse areas of calcification. Identification of the grade of spine. Most tumors arise in the lumbosacral region and the tumor is essential to determine prognosis, and it is involve the vertebral body in up to 90% of patients. As based primarily on the cellularity of the tumor and pleo- an entity, osteosarcoma includes any malignant spindle morphism of the tumor cells. Such information is also tumor that produces osteoid; however, this encompasses useful to determine the usefulness of adjuvant treat- American Academy of Orthopaedic Surgeons 589

Tumors of the Spine Orthopaedic Knowledge Update 8 ments such as radiation therapy. The treatment of chon- in the spine. Originating from remnants of the noto- drosarcoma is complicated by its lack of response to chord, chordomas typically involve either the sacrococ- conventional chemotherapy and/or radiation therapy. cygeal or sphenooccipital regions of the axial skeleton. No known clinical trials have demonstrated any survival The average age at diagnosis is 56 years; however, these benefit among patients receiving chemotherapy, and the tumors can occur in almost any age group. Clinical pre- use of radiation in this patient population is controver- sentation is often subtle, with a gradual onset of neuro- sial. Surgical excision, therefore, is the mainstay of treat- logic symptoms including pain, numbness, motor weak- ment of chondrosarcoma. As a result, the survival rate ness, incontinence, and constipation. Chordomas are of patients with chondrosarcoma is closely associated slowly growing lesions and are often quite large when with adequate lesion excision and clean margins. Me- initially discovered. When located in the sacrum, the dian survival in patients with chondrosarcoma of the mass usually protrudes anteriorly, thereby preventing spine is approximately 6 years. the lesion from causing a noticeable external mass. On radiographic evaluation, the bone from which the tumor Ewing’s Sarcoma arises may demonstrate noticeable changes, but the Ewing’s sarcoma of the spine is a relatively rare entity, most impressive feature of chordomas is the large soft- accounting for only 8% of a large reported series of pa- tissue mass. Unless a significant amount of internal cal- tients with Ewing’s sarcoma. It is actually more common cification is present, the soft-tissue component can be for this tumor to metastasize to the spine from other lo- missed or underestimated on the basis of plain radio- cations than it is for it to originate in the spine as a pri- graphs; therefore, either CT or MRI is required for de- mary tumor. Its clinical features are similar to those for finitive evaluation. On MRI chordomas are lobulated all patients with Ewing’s sarcoma; it most commonly masses with a distinctly myxoid (mucoid) consistency. arises during the second decade of life, and it affects Because they are generally slow-growing tumors, they males more frequently than females. The most common are associated with a pseudocapsule. The histologic ap- presenting symptom among patients with Ewing’s sar- pearance of chordomas can vary from relatively cellular coma is pain, often in the sacrococcygeal area. Although masses to fluid-filled cysts. Classically, they are com- instances of Ewing’s sarcoma involving the cervical posed of chords of physaliphorous cells that are orga- spine have been reported, they are extremely rare. Os- nized into lobules. Similar to chondrosarcoma, chordo- seous findings in patients with Ewing’s sarcoma can be mas demonstrate a poor response to both radiotherapy extremely subtle. Plain radiographs can, therefore, ap- and chemotherapy. Surgical excision with wide margins, pear normal, often belying a large soft-tissue mass. In therefore, offers the only significant possibility of cure this respect, CT or MRI may be far more informative in in these patients. The average 10-year survival rate defining tumor extent. In patients with Ewing’s sar- among patients with sacral chordomas is 20% to 40%, coma, these imaging modalities can demonstrate evi- usually because of recurrence and direct spread of the dence of a large mass originating in the vertebral body, tumor. The reported rate of metastasis varies widely in with variable amounts of internal mineralization. different series, ranging from 10% to 27% for sacral le- C-reactive protein levels and erythrocyte sedimentation sions; however, this rarely represents the cause of death rates are often elevated, and can therefore be useful ad- in patients with chordomas. juncts for the diagnosis of Ewing’s sarcoma. Histologi- cally, Ewing’s sarcomas are composed of sheets of small Multiple Myeloma blue cells, occasionally forming pseudorosettes around Multiple myeloma and its solitary counterpart, plasma- areas of necrosis. Nearly all Ewing’s sarcomas possess a cytoma, are both B-cell lymphoproliferative diseases. characteristic t11:22 chromosomal translocation. Al- Solitary plasmacytoma often progresses to multiple my- though the treatment of patients with Ewing’s sarcoma eloma. Multiple myeloma is the most common primary has varied considerably, the condition currently is malignancy of bone and the spine. Patients often treated using a combination of chemotherapy, surgical present with pain from spontaneous vertebral compres- resection, and radiation therapy, each of which is effec- sion fractures. Multiple punched-out lesions on a lateral tive against this tumor individually. The use of adjuvant skull radiograph are a classic finding, and this warrants a treatments is especially critical given the difficulty of skeletal survey which may reveal other lesions. Bone performing wide resection in the spine. scans are classically negative because of the lack of local bone reaction, and the diagnosis is confirmed with the Chordoma presence of a monoclonal spike with serum electro- Chordomas are the most common nonhematogenous phoresis. Chemotherapy and radiation therapy have primary malignant tumors of the spine, and, unlike long been the mainstays of treatment of this condition. other malignant tumors discussed, they do not normally occur outside of the spine. They account for 1% to 4% With advances in chemotherapeutic treatments, pa- of all primary bone tumors, with 20% of those occurring tients with multiple myeloma often live longer than pa- tients with bone metastases from other malignancies. 590 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 48 Tumors of the Spine This has prompted a more aggressive approach in the sible, excision is indicated. Although epidural lipomas treatment of myeloma affecting the spine to improve are uncommon, they are a well-documented entity and quality of life. Radiation may be quite effective in treat- can cause cord compression. Lipomatosis, especially ing spinal cord compression from epidural tumor. In pa- when steroid-induced, is another possible diagnosis in tients with vertebral collapse with neurologic symptoms patients with extradural tumors. Extradural tumors can or advanced kyphosis, surgery may be indicated. Even initially be observed using MRI, but excision is recom- with more advanced disease, surgical decompression mended in patients with any progressive neurologic def- and reconstruction may be warranted, and the outcomes icits. Epidural hemangioma and meningioma are both from a recent study seem to favor this approach in care- rare. fully selected patients. Similarly, in patients with my- eloma and pathologic vertebral compression fractures, Intradural-extramedullary tumors make up approxi- kyphoplasty has been shown to result in improved qual- mately 85% of intradural tumors and largely consist of ity of life as well as correction of vertebral deformity. neurofibromas, meningiomas, and ependymomas. The two predominant intramedullary tumors are astrocy- Metastatic Tumors toma (high and low grade) and ependymomas, with he- mangiomas and lipomas being exceedingly rare. As with Because the spine is the most common site of skeletal extradural neurofibromas, the intradural counterpart involvement of metastatic disease, metastases account also arises from the nerve roots, usually the dorsal sen- for most tumors surgically encountered in the spine. Ap- sory roots. The so-called “dumbbell” tumor is an intra- proximately 50% of these tumors arise from carcinoma dural neurofibroma that is following the nerve root (lung or breast), lymphoma, or myeloma. In regard to through the foramen. Again, complete excision is the the solid tumor primaries, breast, lung, and prostate are treatment of choice. Meningiomas are usually found in the most common, followed by renal, thyroid, gas- the anterolateral canal and should be excised when trointestinal, and rarely primary soft-tissue sarcomas. identified. Ependymomas usually arise from within the Breast, prostate, and renal metastases are more likely to cord and should be excised; however, extramedullary be seen by the spine surgeon than either pulmonary or ependymomas can arise from the tip of the conus at its gastrointestinal tumors because of longer patient sur- junction with the filum terminale. Astrocytomas are in- vival rates. tramedullary and should be excised. High-grade astrocy- tomas have no visible margin and are usually debulked The most common and usually the first symptom of followed by neoadjuvant chemotherapy. Patients with spinal metastases is that of localized pain, which may high-grade astrocytomas have a bleak prognosis. occur at night and awaken patients from sleep. Patients may also present with radicular or myelopathic symp- Diagnosis and Evaluation toms. If a suspected metastatic spinal lesion is found, a search for the primary tumor as well as for other sites of The most common presenting symptom among patients metastatic disease must be made. This workup may with tumors of the spine is pain, which is reported by identify other lesions that are more accessible for biopsy more than 80% of patients at initial visit. Typically, tu- than the spine. The type of tumor often dictates the mors with a more rapid onset of pain reflect more ag- treatment; however, the goals of treatment include de- gressive tumors, whereas benign or more slowly growing creasing the tumor burden, relief of pain, prevention tumors may be characterized by gradually increasing and reversal of neurologic deficits, and preserving or re- pain spanning several months to years, with sudden in- storing spinal stability. The modes of treatment will be creases in pain suggesting pathologic fracture. Neuro- discussed later in the chapter. logic compromise can also be a presenting symptom be- cause of compression of either nerve roots or the spinal Spinal Cord Tumors cord. Depending on the precise location and size of the tumor, neurologic symptoms can range from subtle mo- Tumors of the spinal cord are divided into three catego- tor or sensory deficits to paraplegia. Other presenting ries: extradural, intradural-extramedullary, and intra- symptoms such as spinal deformity are considerably less medullary. common. A careful history should also include constitu- tional symptoms such as weight loss, fevers and chills, Extradural tumors are very uncommon. The most and lethargy as well as a complete medical history, in- common malignancy in the epidural space is lymphoma, cluding any personal history or family history of malig- with most being spread from the vertebral body or nancy. paraspinous nodes; however, a small number do arise primarily from the epidural space. Excision and poste- Radiographic evaluation generally begins with plain rior neural decompression is usually the treatment of films, with notation of the location of the lesion, any choice for extradural tumors. Ten percent of neurofibro- soft-tissue extension, the zone of transition, and internal mas are extradural. They usually arise from a spinal characteristics. For tumors involving the spine, certain nerve root, and because malignant degeneration is pos- American Academy of Orthopaedic Surgeons 591

Tumors of the Spine Orthopaedic Knowledge Update 8 Figure 2 Enneking’s oncologic stages (IA, IIA, IB, and IIB) of malignant tumors to the spine. 1 = tumor capsule, 2 = pseudocapsule, 3 = tumor with pseudocapsule, 4 = skip metastases. (Reproduced with permission from Boriani S, Biagini R, DeJure F: Bone tumors of the spine and epidural cord compression: Treatment options. Semin Spine Surg 1995;7:317-322.) Figure 1 AP radiograph demonstrating the winking owl sign in which the right-sided necrosis, and extent of marrow involvement. When the pedicle has been destroyed by tumor, so that the pedicle ring is absent (arrow). lesion is primarily bony, CT provides excellent detail and is a valuable tool for preoperative planning. For pa- classic radiographic signs have been described, such as tients with malignant tumors or metastatic disease, stag- the winking owl sign, in which the pedicle has been ing studies should also include a chest radiograph, chest, eroded by an expanding tumor (Figure 1), or vertebra abdominal, and pelvic CT, and bone scan. Finally, before plana, in which there is vertebral body collapse. Al- beginning any definitive treatment, a pathologic diagno- though these signs are considered to be classic radio- sis should be obtained by performing a biopsy, either graphic signs for spinal lesions, they are typically seen CT-guided or open, depending on the location and size only after considerable bony destruction has occurred. of the lesion. Advanced imaging studies are mandatory in any evalua- tion of spinal tumors. MRI provides not only unparal- Staging systems attempt to predict outcome among leled soft-tissue detail, but it also evaluates the neural patients with benign and malignant tumors by using elements. MRI can reveal important tissue characteris- clinical variables such as the histologic grade of the tu- tics of the tumor, such as density, vascular perfusion and mor, local behavior, and metastatic spread. In bone and soft-tissue sarcomas, staging systems have also been de- signed as preoperative aides to define the surgical plan- ning for optimal local control. For benign tumors of bone, the Enneking system is commonly used and di- vides tumors into one of three categories: inactive, ac- tive, and aggressive. To address malignant bone lesions, Enneking developed a surgical staging system based on the grade of the tumor, intracompartmental or extra- compartmental status, and metastatic disease (Figure 2). Although this staging system has been adopted for the staging of pelvic and extremity tumors, it has proved to be less useful in the treatment of spinal tumors. A stag- 592 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 48 Tumors of the Spine ing system for spinal tumors was developed based on the lesion’s location and local extension (Figure 3). The vertebral body is divided into twelve sectors similar to a clockface, and the tumor location is plotted according to this grid. Furthermore, five layers are described, begin- ning with the paraspinal soft tissues peripherally to the intradural space centrally. The system is primarily de- scriptive, and it can therefore be for the staging of both benign and malignant tumors. The Harrington staging system has been applied to metastatic spinal tumors (Figure 4). Nonsurgical Treatment Figure 3 Proposed system of surgical staging of spine tumors, defining the extent of the tumor. A = extraosseous soft tissues, B = intraosseous (superficial), C = in- The management of patients with benign primary tu- traosseous (deep), D = extraosseous (extradural), E = extraosseous (intradural), and mors includes close clinical and radiographic observa- M = metastasis. Numbers 1 through 12 represent location of tumor. (Reproduced with tion. Bracing has a limited role in treatment, but it may permission from Boriani S, Weinstein JN, Biagini R: Primary bone tumors of the spine. provide some symptomatic relief of pain. Specific strate- Spine 1997;22:1036-1044.) gies for certain tumors have been discussed individually. Surgical excision should be considered when the patient and/or neurologic deterioration may be considered. Spe- has evidence of neurologic deficit, tumor progression, cific treatment considerations for the various types of progressive deformity, or pain. spinal tumors have been discussed. In patients with highly vascular tumors such as renal cell carcinoma, pre- In patients with malignancies, chemotherapy plays operative tumor embolization may help reduce intraop- an important role in treating tumors such as osteosar- erative bleeding. In general, the location and extent of coma, Ewing’s sarcoma, and lymphoma for which che- the tumor dictate the approach (anterior, posterior, or motherapeutic regimens have proved to be systemically combined), and the extent of destabilization caused by effective. Chemotherapy can be used both preopera- the decompression or removal of tumor then deter- tively and postoperatively as an adjuvant agent, and in mines the method of restabilization and reconstruction some patients, it can even be used as a primary treat- of the spine. The immediate proximity of vital structures ment to reduce tumor burden. Stem cell and bone mar- (particularly the neural elements) to the tumor often row salvage is allowing higher doses of chemotherapy to precludes wide surgical excision, and spinal tumors are be administered for longer periods, which in turn is invariably treated with intralesional surgery. Such sur- more lethal to tumors. Radiation therapy, as with che- geries are therefore palliative, and are performed in an motherapy, can be used either as an adjuvant or primary attempt to improve the quality of the patient’s life. treatment. Patients with radiosensitive tumors (lung, prostate, breast) who present early with metastatic dis- Spinal Stability ease without spinal instability or dense neurologic com- promise can be managed with radiation therapy. In pa- The definition of spinal instability in the setting of ver- tients with higher tumor load requiring surgical tebral destruction by tumor remains elusive. Unlike long intervention, external beam irradiation can be used as bones, the spine may continue to exhibit a degree of an adjuvant therapy either preoperatively or postopera- load bearing without catastrophic failure after fracture, tively. Recent advances in radiosurgery allow the deliv- so that the concept of patients being at risk for patho- ery of a single, large dose of radiation (proton beam) to logic fracture is not as intuitive for those with tumor- a localized tumor using a stereotactic approach, result- related spinal instability. Although various criteria for ing in precise delivery to the target. This may be useful spinal stability in the face of spinal tumors have been in the treatment of chordomas, recurrent tumors, or sar- reported, they have not been particularly useful in pre- comas without clear resection margins. dicting which patients may benefit from spinal surgery before the development of profound instability or neu- Surgical Treatment rologic deficit. The primary goals of surgery in patients with spinal tu- Varied grading systems and parameters have been mors are to reduce pain, to preserve or restore neuro- devised to determine when surgical intervention is re- logic function, and to establish spinal column structural integrity. Less commonly, excision of the tumor in an at- tempt at a cure is performed. In patients with tumors that do not respond to radiotherapy and chemotherapy, earlier surgery to prevent impending vertebral collapse American Academy of Orthopaedic Surgeons 593

Tumors of the Spine Orthopaedic Knowledge Update 8 Figure 4 Illustration of Harrington’s clas- sification of spinal metastases. Numbers 1 through 4 represent the anatomic loca- tion of tumor. A = tumor confined to the vertebra; B = tumor extends beyond the vertebra; C = distant metastases. (Repro- duced from Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, Ameri- can Academy of Orthopaedic Surgeons, 1999, pp 723-736.) quired to treat impending instability as a result of to unnecessary risks, morbidity, and a prolonged recov- pathologic vertebral replacement. In the thoracic spine, ery. In patients for whom posterior stability is main- 50% to 60% of vertebral body involvement or 25% to tained, reconstructing the anterior spinal column with 30% of body involvement with costovertebral involve- anterior surgery only after tumor removal may be all ment have been suggested as criteria for impending col- that is necessary. The corollary to this is that performing lapse. In the lumbar spine the suggested criteria for im- “too little” surgery does the patient a similar disservice. pending collapse are 35% to 40% of body involvement In patients with significant comorbidities and reduced alone or 25% of body involvement with pedicle or pos- life expectancy, it is tempting to perform a lesser proce- terior body involvement. Even when adhering to these dure. If however the patient does not leave the operat- guidelines, each patient should be assessed individually, ing room with effective neural decompression and spi- taking tumor load, type, location, and prognosis of the nal stability, the likelihood of early or late failure is patient into account. More recently, finite element mod- great. Having to return a patient to surgery after a els have shown that tumor size, magnitude of spinal failed initial surgical procedure is an extremely undesir- loading, and bone density are predictive of the initiation able and potentially avoidable situation. of burst fractures in metastatically affected vertebrae and that pedicle involvement and disk degeneration are In general, the site of the lesion dictates the surgical less important. approach. When the vertebral body is involved and neu- ral compression is anterior, an anterior approach will al- Radiation Treatment low for tumor resection and direct decompression of the neural elements. Anterior reconstruction, usually involv- In patients with spinal tumors causing neural compres- ing a strut spanning the excised level or levels is re- sion, treating physicians are required to weigh the rela- quired to restore spinal stability. The involved segments tive advantages of initiating treatment with radiation are typically further stabilized with rigid anterior instru- therapy against primary surgical decompression. If the mentation. If the morbidity of an anterior approach is tumor is radiosensitive and neural progression is grad- prohibitive, vertebral body excision and anterior neural ual, radiotherapy may be the initial treatment of choice. decompression may be accomplished through a postero- Patients with limited ambulatory function as a result of lateral approach involving removal of the pedicles so tumor causing neural compression have a 60% chance that the vertebral body can be accessed lateral to the of improvement after undergoing radiation treatment. dura. A posterior approach is also preferred when the Patients who have lost sphincter function have less than tumor involves the posterior elements (Figure 5). The a 40% chance of regaining function after radiation posterior approach will also allow for multilevel poste- treatment. When spinal radiation is ineffective in im- rior segmental fixation to stabilize the spine, whereas proving neurologic deficits, subsequent surgical decom- anterior approaches tend to allow for stabilization of pression is fraught with complications. Operating fewer segments. If both the vertebral body and posterior through a radiated field will increase the risk of wound elements of the spine are involved, posterior instrumen- nonhealing and surgical site infections. In some patients, tation in addition to anterior decompression-recon- radiation injury to the skin in the surgical field may pre- struction will be necessary to stabilize the involved vent or delay surgical intervention. In addition, the po- spine (Figure 6). Isolated laminectomy has a small role tential advantages of initiating radiation treatments af- in the treatment of spinal tumors. ter surgical resection (when the tumor volume has been significantly reduced) must be considered. Optimal timing of treatments such as chemotherapy and radiation therapy after spinal surgery remains Surgical Approach poorly defined. These treatments will interfere with wound healing as well as with bone graft incorporation Performing an anterior and posterior surgery when ei- and fusion. Animal research suggests that radiation ther- ther approach alone would suffice exposes the patient apy should be delayed for 6 weeks after spinal recon- 594 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 48 Tumors of the Spine Figure 5 AP (A) and lateral (B) radiographs of a 29-year-old man with a 2-year history of slowly progressive low back pain; the pain oc- casionally radiated to the right thigh, but no paresthesias nor weakness was reported. The AP radiograph is significant for a classic wink- ing owl sign at the right pedicle of L4 (arrow). C, A subsequent CT scan reveals an expansile lesion involving the right pedicle and trans- verse process of L4 that contains a limited amount of intralesional mineralization. D, MRI further demonstrates the extent of the lesion and suggests that the lesion may be com- pressing the L3 nerve root. No central com- pression was present. Clinical history and im- aging suggested a benign lesion, although a precise diagnosis was not possible. Osteoblas- toma was considered to be the most likely di- agnosis. E, Histologic analysis of the pathol- ogy specimen contained polygonal chondroblasts with numerous giant cells, indi- cating that the lesion was, in reality, a chon- droblastoma. F, Postoperative AP and lateral radiographs show that an excision was per- formed with posterior instrumented L3-L5 fu- sion. struction involving arthrodesis to permit the critical This has been reported to provide palliation in many se- early phases of bone graft revascularization. Obviously, ries; however, the recurrence rates have been quite high. decisions regarding the timing of adjuvant treatments This has prompted interest in en bloc spondylectomy need to be made by taking into account the likely for the treatment of patients with solitary metastases or course of the patient’s underlying malignancy. intracompartmental primary malignant tumors. In case reports, en bloc resection or total spondylectomy has En Bloc Tumor Resection been suggested to decrease recurrence and improve sur- vival. En bloc spondylectomy usually involves removal Surgery for spinal tumors typically involves intralesional of the posterior elements and osteotomy of the pedicles, excision with debulking followed by adjuvant therapy. followed by posterior stabilization with pedicle fixation American Academy of Orthopaedic Surgeons 595

Tumors of the Spine Orthopaedic Knowledge Update 8 Figure 6 AP (A) and lateral (B) radio- graphs of a 44-year-old man with a several-month history of progressive neck pain, no radicular symptoms, and no up- per motor neuron signs at presentation demonstrate a lesion (arrow) involving the body and posterior elements of the C3 vertebra with soft-tissue extension. C, Ax- ial CT demonstrates the mass and sug- gests that it contains mineralized matrix. D, MRI further delineates the extent of the tumor and reveals that there is no spinal cord compression. The patient underwent a CT-directed biopsy of the C3 mass, and the results of histologic analysis (E) were most consistent with the presence of a low-grade chondrosarcoma. Because wide resection was not possible because of the proximity of the mass to both vertebral ar- teries and the spinal cord, the patient un- derwent preoperative radiotherapy, fol- lowed by a front-back resection of C3 with an anterior cage/C2-C4 plate and C2-C5 posterior instrumentation. Intraoperative radiotherapy was administered to the an- terior dura, and the patient underwent proton radiotherapy postoperatively. F, Postoperative radiograph. one to two levels above and below the resected level. vere pain and preventing neurologic impairment, includ- This is followed by the en bloc removal of the vertebral ing retention of bowel and bladder control. Recent stud- body and reconstruction of the anterior column, which ies have demonstrated that in appropriately selected can be accomplished either through the same posterior patients, surgical management is able to positively affect surgical approach or through a separate anterior ap- the overall quality of life in those with spinal me- proach. tastases. Metastatic Disease Vertebral Augmentation Diffuse metastatic disease still poses a significant chal- Vertebroplasty and kyphoplasty have shown promise in lenge for the spinal surgeon, and the combination of de- the treatment of patients with multiple myeloma or spi- bulking, intralesional excision, and spinal reconstruction nal metastases. These percutaneous modalities have is the mainstay of treatment. The surgical approach is ei- been widely used for the treatment of benign os- ther anterior, posterior, or both, depending on the loca- teoporotic fractures and are increasingly being used to tion of the tumor. Even though surgery is palliative, it treat pathologic compression fractures caused by meta- can enhance a patient’s quality of life by relieving se- static disease and vertebral body pain secondary to tu- 596 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 48 Tumors of the Spine mor infiltration. The indications for these techniques in- Nonsurgical Treatment clude refractory pain without neurologic compromise. The posterior vertebral body wall must be intact to pre- Ryu S, Fang YF, Rock J, et al: Image-guided and vent extravasation of cement into the spinal canal. intensity-modulated radiosurgery for patients with spi- Short-term results appear promising, with good and nal metastasis. Cancer 2003;97:2013-2018. rapid relief of pain, improved function, and even resto- ration of vertebral body height with kyphoplasty in In this study, 10 patients with spinal metastasis were some patients. Most reported complications in patients treated with image-guided and intensity-modulated radiosur- who have undergone vertebroplasty have been the re- gery. The authors reported that the most patients had pain re- sult of extravertebral cement extravasation. This risk is lief within 2 to 4 weeks of treatment. higher when treating patients with metastatic as op- posed to osteoporotic vertebral fractures. Kyphoplasty, Surgical Treatment which involves the creation of an intravertebral cavity with a balloon tamp, has a lower risk of extravertebral Dudeney S, Lieberman IH, Reinhardt MK, Hussein M: cement extravasation than vertebroplasty. Although Kyphoplasty in the treatment of osteolytic vertebral these minimally invasive treatments may not impact the compression fractures as a result of multiple myeloma. prognosis or the disease process, they can provide sub- J Clin Oncol 2002;20:2382-2387. stantial and immediate pain relief with a reported low risk of complications. Fifty-five consecutive kyphoplasties were prospectively evaluated in 18 patients. Mean follow-up was 7.4 months, and Annotated Bibliography there was significant improvement in Short Form-36 scores for bodily pain, physical function, vitality, and social function. Primary Tumors Fourney DR, Schomer DF, Nader R, et al: Percutaneous Abe E, Koboyashi T, Murai H, et al: Total spondylec- vertebroplasty and kyphoplasty for painful vertebral tomy for primary malignant, aggressive benign and soli- body fractures in cancer patients. J Neurosurg 2003;98: tary metastatic bone tumors of the thoracolumbar spine. 21-30. J Spinal Disord 2001;14:237-246. In this study, 97 procedures (65 vertebroplasty and 32 ky- Fourteen patients with malignant or aggressive benign ver- phoplasty) were performed in 56 patients with myeloma and tebral tumors of the thoracolumbar spine underwent total primary malignancies. The authors report that 84% of patients spondylectomy. Pain relief was achieved in all 14 patients, and experienced complete pain relief at a median follow-up of 4.5 no serious complications occurred. Local recurrence was months. found in three patients at a mean follow-up of 3.2 years. Total spondylectomy appears to be an effective method for control- Krepler P, Windhager R, Bretschneider W, et al: Total ling local recurrence without major complications. vertebrectomy for primary malignant tumors of the spine. J Bone Joint Surg Br 2002;84:712-715. Durr HR, Wegener B, Krodel A, Muller PE, Jansson V, Refior HJ: Multiple myeloma: Surgery of the spine. Ret- Vertebrectomy was performed on seven patients, with a rospective analysis of 27 patients. Spine 2002;27:320-324. mean follow-up of 52 months. In five patients, a wide resection was achieved. The authors conclude that vertebrectomy seems This is a report on the clinical course of 27 consecutive pa- to be an appropriate procedure for the treatment of primary tients who were surgically treated for solitary or multiple my- lesions of the spine. eloma of the spine. Life quality, reported to be 48% before surgery, improved to 59% 1 month after surgery and to 73% Sundaresan N, Rothman A, Manhart K, Kelliher K: Sur- in 24 survivors after 1 year. The authors concluded that surgi- gery for solitary metastases of the spine, rationale and cal treatment of myeloma of the spine seemed to be an effec- results of treatment. Spine 2002;27:1802-1806. tive method of treatment with respect to neurologic function and life quality in selected patients. This is a retrospective review of 80 consecutive patients with solitary sites of spine involvement from solid tumors. The Ghanem I, Collet LM, Kharrat K, et al: Percutaneous overall median length of survival after surgery was 30 months. radiofrequency coagulation of osteoid osteoma in chil- Complete surgical excision before irradiation was recom- dren and adolescents. J Pediatr Orthop B 2003;12:244- mended to increase the prospects of palliation and possible 252. cure. In this study, 23 patients who underwent percutaneous ra- Wai EK, Finkelstein JA, Tangente RP, et al: Quality of diofrequency coagulation for osteoid osteoma were retrospec- life in surgical treatment of metastatic spine disease. tively reviewed. Pain disappeared immediately after the proce- Spine 2003;28:508-512. dure in 21 patients. At an average of 3.5-year follow-up, all patients were pain free. In this study, 25 consecutive patients undergoing surgery for spinal metastases were prospectively evaluated. After sur- gery, the largest improvement was with pain, but there were also improvements with tiredness, nausea, anxiety, drowsiness, appetite, and well-being. American Academy of Orthopaedic Surgeons 597

Tumors of the Spine Orthopaedic Knowledge Update 8 Whyne CM, Hu SS, Lotz JC: Burst fracture in the meta- cutaneous catheter embolisation. Neuroradiology 1972; statically involved spine: Development, validation, and 3:160-164. parametric analysis of a three-dimensional poroelastic finite-element model. Spine 2003;28:652-660. Kostuik JP, Errico TJ, Gleason TF, Errico CC: Spinal sta- bilization of vertebral column tumors. Spine 1988;13: A finite-element study and in vitro experimental valida- 250-256. tion was performed for an investigation of features that con- tribute to burst fracture risk. The authors report that the prin- Marsh BW, Bonfiglio M, Brady LP, Enneking WF: Be- cipal factors affecting the initiation of fracture were tumor nign osteoblastoma: Range of manifestations. J Bone size, magnitude of spinal loading, and bone density. Joint Surg Am 1975;57:1-9. Classic Bibliography Pettine KA, Klassen RA: Osteoid osteoma and osteo- blastoma of the spine. J Bone Joint Surg Am 1986;68: Bohlman HH, Sachs BL, Carter JR, Riley L, Robinson 354-361. RA: Primary neoplasms of the cervical spine. J Bone Joint Surg Am 1986;68:483-494. Samson IR, Springfield DS, Suit HD, Mankin HJ: Oper- ative treatment of sacrococcygeal chordoma: A review Boriani S, Biagini R, De Iure F, et al: En bloc resections of twenty-one cases. J Bone Joint Surg Am 1993;75:1476- of bone tumors of the thoracolumbar spine: A prelimi- 1484. nary report of 29 patients. Spine 1996;21:1927-1931. Shives TC, Dahlin DC, Sim FH, Pritchard DJ, Earle JD: Galasko CS, Norris HE, Crank S: Spinal instability sec- Osteosarcoma of the spine. J Bone Joint Surg Am 1986; ondary to metastatic cancer. J Bone Joint Surg Am 2000; 68:660-668. 82:570-594. Stener B: Complete removal of vertebra for extirpation Hart RA, Boriani S, Biagini R, Currier B, Weinstein JN: of tumors: A 20 year experience. Clin Orthop 1989;245: A system for surgical staging and management of spine 72-82. tumors: A clinical outcome study of giant cell tumors of the spine. Spine 1997;22:1773-1783. Sundaresan N, Galicich JH, Lane JM, et al: Treatment of neoplastic epidural cord compression by vertebral body Harrington KD: The use of methylmethacrylate for resection and stabilization. J Neurosurg 1985;63:676-684. vertebral-body replacement and anterior stabilization of pathologic fracture-dislocations of the spine due to met- Sundaresan N, Steinberger AA, Moore F, et al: Indica- astatic malignant disease. J Bone Joint Surg Am 1981;63: tions and results of combined anterior-posterior ap- 36-46. proaches for spine tumor surgery. J Neurosurg 1996;85: 438-446. Harrington KD: Anterior decompression and stabiliza- tion of the spine as a treatment for vertebral collapse Yuh WT, Quets JP, Lee HJ, et al: Anatomic distribution and spinal cord compression from metastatic malig- of metastases in the vertebral body and modes of he- nancy. Clin Orthop 1988;233:177-197. matogenous spread. Spine 1996;21:2243-2250. Hekster RE, Luyendijk W, Tan TI: Spinal cord compres- sion caused by vertebral haemangioma relieved by per- 598 American Academy of Orthopaedic Surgeons

Chapter 49 Spondyloarthropathy Tushar Patel, MD Mark J. Romness, MD Introduction articular manifestations and a more aggressive disease course. Patients with rheumatoid arthritis who have a Many inflammatory diseases are known to occur in the negative rheumatoid factor may eventually convert to a musculoskeletal system, but the primary inflammatory positive rheumatoid factor and follow a similar clinical conditions that affect the spine, in descending preva- progression as patients who are initially positive. Severe lence, are rheumatoid arthritis, ankylosing spondylitis, spinal involvement is primarily cervical in patients with and juvenile rheumatoid arthritis. These three inflamma- rheumatoid arthritis, and up to 85% of patients with tory conditions alone are estimated to affect over 3 mil- rheumatoid arthritis develop cervical radiographic lion patients in the United States. Juvenile rheumatoid changes within 10 years of disease onset. Lumbar prob- arthritis is discussed in chapter 21. lems are less significant, but low back pain was present in 40% and radiographic evidence of lumbar pathology Rheumatoid Arthritis was found in 57% of 106 patients with rheumatoid ar- thritis. The primary spinal deformities in rheumatoid ar- Definition thritis are atlantoaxial subluxation, superior migration of the odontoid, and subaxial subluxation (Figure 1). All Rheumatoid arthritis is a systemic autoimmune disease of these conditions can lead to neurologic impairment. of unknown etiology that causes progressive joint swell- Superior migration of the odontoid is also known as ing, pain, and stiffness secondary to synovitis. The onset basilar invagination, cranial settling, and atlantoaxial im- of symptoms usually occurs between 20 and 45 years of paction. age. Seventy percent of patients with rheumatoid arthri- tis are female. A genetic component continues to be Natural History supported but is not well defined. A positive rheuma- toid factor is present in approximately 85% of patients, The progressive nature of rheumatoid arthritis is well but is not specific for rheumatoid arthritis and can be known, as is the variable expression of the disease in present in normal individuals and in other medical con- different patients. Several studies have attempted to cor- ditions. A positive rheumatoid factor is clinically associ- ated with more severe symptoms, including extra- American Academy of Orthopaedic Surgeons Figure 1 Lateral radiograph (A) and cor- responding sagittal MRI (B) showing the combined manifestations of cranial set- tling, atlantoaxial subluxation, and subax- ial subluxation. 599

Spondyloarthropathy Orthopaedic Knowledge Update 8 myelopathy secondary to irreducible atlantoaxial sub- luxation, all were confined to bed within 3 years and died within 8 years. Imaging Plain Radiographs Plain radiographs remain the standard modality to diag- nose, classify, and monitor spinal arthropathy. Plain im- ages provide cost-effective screening for skeletal changes. Early radiographic changes including the pres- ence of osteophytes and disk space narrowing may not be symptomatic. Flexion and extension lateral views are used to define stability between the spinal segments and are the primary method to assess the cervical spine for the primary spinal deformities that occur in rheumatoid arthritis. The use of select digital imaging and software allows electronic measurements such as the atlanto-dens interval. Magnetic Resonance Imaging MRI provides information on soft tissues and structural bone details not seen with conventional radiography. To- mographic representation clarifies anatomic structures, and the use of gadolinium enhancement has been shown to increase the sensitivity of diagnosis and to help in de- termining the extent of the disease. Dynamic studies are possible with MRI (Figure 2), but when dynamic MRI and plain flexion-extension films were compared in 23 patients with rheumatoid arthritis, the magnitude of at- lantoaxial subluxation was less with MRI in all patients; MRI was not able to detect atlantoaxial subluxation that was seen in four patients using radiography. MRI is required for evaluation of neurologic structures and is the standard method for evaluation of superior migra- tion of the odontoid. Correlation of cord compression or impingement at the atlantoaxial level on initial MRI and development of subarachnoid space encroachment on sequential MRI scans have both been shown to be predictive of neurologic deterioration. Figure 2 Dynamic flexion-extension MRI panels showing evidence of dynamic cord CT Myelogram and Bone Scan compression at the occipitocervical junction. The use of CT myelograms is beneficial for unique situ- ations such as for patients who had previous surgery relate serologic tests and radiographic changes with cer- and who have ferromagnetic implants in the area to be vical progression. Rheumatoid factor-positive serology, imaged, or for those who are not candidates for MRI more extensive peripheral joint involvement, male gen- because of cochlear implants, pacemakers, or neurostim- der, and corticosteroid use are factors that have been ulators.Nuclear imaging is a sensitive screening tool for linked to greater cervical involvement. Cervical myelop- identifying occult fractures in patients with rheumatoid athy has been associated with progression to bed con- arthritis. The advantage over MRI is the ability to image finement or death within an average of 35 months if un- the whole body efficiently and cost-effectively. treated in patients with rheumatoid arthritis and extensive mutilating-type changes of the peripheral Bone Density Studies joints. In 21 untreated patients with rheumatoid arthritis Osteoporosis is common in most forms of spinal ar- thropathy. Contributing factors include the disease pro- cess itself, genetics, limitations in activity, nutrition, and 600 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 49 Spondyloarthropathy treatments such as the use of corticosteroids. However, the presence of osteoporosis is not limited to patients with severe disease or those treated with corticosteroids. Bone density studies quantitate the extent of osteoporo- sis and help determine whether treatment is indicated. Indications for Surgery Figure 3 An example of posterior occiputocervical fusion construct. Neurologic impairment is the most urgent indication for Instrumentation surgery in patients with spinal arthropathy. Impairment Wire fixation is extensively used for stabilization in the can be determined by history, clinical examination, elec- cervical spine and has been described in the literature. trodiagnostic studies, or MRI. Because progression of Additional methods for instrumentation of the cervical myelopathy is the natural history in rheumatoid arthri- spine have been recently described. At the occipital tis, any myelopathic findings should be considered a sur- area, cranial bolts placed using the inside-outside tech- gical indication. nique and connected to plates and lateral mass screws were used for 21 patients with rheumatoid arthritis; re- Pain and instability often are associated with neuro- sults showed no instrument failures and significantly re- logic involvement, except in patients with gradual dis- duced pain scores. Cadaver studies have shown in- placement over time. Pain alone is a subjective indica- creased axial rotation stiffness with rod and screw tion; instability without neurologic deficit has specific fixation (Figure 3) compared with plate and screw or parameters to warrant surgery. These parameters in- loop and cable constructs, and better restoration of sag- clude posterior atlanto-dens interval of 14 mm or less in ittal plane balance and maintenance of correction. flexion on plain radiographs for atlantoaxial subluxation and MRI findings of cord diameter of less than 6 mm in The use of screws throughout the spine has in- flexion, cervicomedullary angle of less than 135°, and 13 creased treatment options. Transarticular C1-2 fixation, mm or less of space available for the spinal cord. Supe- and more recently, segmental fixation of C1 to C2 using rior migration of the odontoid alone is not an indication polyaxial screws inserted into the lateral masses of C1, for surgery and documentation of neurologic impinge- has replaced the requirement of fusion from the occiput ment or myelopathy on flexion MRI or by examination to C2 (or lower) in most instances when C1 laminec- should be documented before surgery is recommended. tomy is performed. The technique of placing screws into the lateral mass of C1 increases the risks of bleeding Spinal fractures in patients with rheumatoid arthritis from the venous plexus accompanying the dorsal ramus usually require fixation, and fixation needs to compen- of the C2 nerve root as well as direct injury to the root, sate for the often-associated osteoporosis and accompa- but affords additional safety compared with the use of nying deformity. This may require fusion and instrumen- tation of more levels than would ordinarily be considered for patients with normal bone quality. Surgical Treatment Decompression Myelopathy may require decompression if the defor- mity is fixed, but reduction of the deformity may pre- serve bony areas for fusion healing. Solid fusion pre- vents spinal cord irritation and has been shown to relieve myelopathy. Anterior transoral decompression was previously recommended for spinal cord compres- sion, but the only current indication for transoral de- compression is the presence of cranial nerve deficits. Arthrodesis Arthrodesis is the treatment of choice for either pri- mary instability resulting from inflammatory process or secondary instability caused by late manifestations of pseudarthrosis or sterile spondylodiskitis. Fusion to the occiput is indicated when adequate fixation at C1 is not possible or when there is instability at the occiput–C1 junction. American Academy of Orthopaedic Surgeons 601

Spondyloarthropathy Orthopaedic Knowledge Update 8 transarticular screws because the path of the vertebral and spreads cephalad. Neck pain caused by spontaneous artery is avoided. anterior atlantoaxial subluxation has been reported as an initial symptom. One study showed that 49% of pa- Surgical Outcomes tients (89 of 181) with ankylosing spondylitis had radio- graphic changes, but atlantoaxial subluxation was The benefits of surgical intervention have been well present in 2% to 20% of patients with ankylosing documented and recent outcomes studies have sup- spondylitis compared with 16% to 25% of adult patients ported this treatment option. For irreducible atlantoax- with rheumatoid arthritis; superior migration of the od- ial instability with myelopathy in patients with rheuma- ontoid has not been reported with ankylosing spondyli- toid arthritis, C1 laminectomy and fusion with tis alone. rectangular rod fixation from the occiput to C2 (16 pa- tients) to C3 (2 patients) or to C4 (1 patient) led to 68% Natural History improvement of at least one Ranawat class and 5- and 10-year survival rates of 84% and 37%, respectively. The natural history of ankylosing spondylitis is progres- Without surgery, 21 matched patients were all bedridden sive loss of posture and mobility. The rate of progression within 3 years and died within 8 years. Similar neuro- is variable. Mild spinal changes in ankylosing spondylitis logic improvements were noted in 67% of patients (37 occur first, with squaring of the lumbar bodies and syn- of 55) with occipital neuralgia, myelopathy, or both desmophytes. More severe involvement leads to changes treated with various procedures. Mortality at 2 years characteristic of so-called “bamboo spine.” Spinal defor- was 27% and resulted mainly from nonsurgery-related mity in ankylosing spondylitis develops secondary to causes. limitation of motion at ankylosed areas or increased motion at nonankylosed areas. Pain can develop at re- Patients with inflammatory spondylitis often have maining motion segments but resolves once that seg- multiple comorbid medical conditions that contribute ment is ankylosed. Ankylosis in a relatively kyphotic po- significantly to management and potential complica- sition occurs at the cervical, thoracic, and lumbar spine, tions. Involvement of the temporomandibular joint may but etiology for kyphosis has not been defined. interfere with intubation, and peripheral joint contrac- tures can make surgical positioning and rehabilitation With long rigid spinal segments and focused areas of more challenging. Osteoporosis impairs fixation poten- osteoporosis, fractures are common even with minimal tial, and many authors recommend the use of orthotic trauma and can cause significant morbidity and mortal- devices after surgery if osteoporosis is present. Poor ity. Mortality can occur from initial injury, fracture treat- skin quality, impaired healing, and dental problems in- ment, or epidural hematomas that can develop up to crease the risk of infection. Despite all the potential weeks after injury. Recent articles on trauma have em- risks, careful patient preparation and planning com- phasized the importance of strict neck immobilization bined with up-to-date skilled care can improve function for patients with ankylosing spondylitis, even in those and survival. who have experienced mild low-energy injuries. Ankylosing Spondylitis Imaging Definition Plain Radiographs Plain radiographs may provide clues for the initial diag- Ankylosing spondylitis is the prototype disease of se- nosis of ankylosing spondylitis. Classic changes at the ronegative spondyloarthropathies—a family of arthritic sacroiliac joints may not be identified initially, but initial conditions not associated with positive rheumatoid fac- presentation with thoracic spine changes in a female pa- tor serology. Other related conditions are reactive ar- tient has been reported. Spondylodiskitis (also known as thritis (Reiter’s syndrome), spondylitic forms of psori- Andersson lesions) is a destructive diskovertebral lesion atic arthritis and inflammatory bowel disease (Crohn’s occurring in ankylosing spondylitis that usually occurs at disease), juvenile spondyloarthropathy, and undifferenti- the thoracolumbar junction. Both inflammatory and ated spondyloarthropathy. Disease onset typically oc- noninflammatory types of destructive lesions occur. The curs between the ages of 20 and 30 years. Males are inflammatory type is defined radiologically as a reduced more commonly affected, and symptoms in females are disk space with a defect of vertebral bodies and dense usually milder and harder to diagnose. Early symptoms cancellous bone sclerosis. The noninflammatory type is of ankylosing spondylitis are commonly overlooked in associated with a fracture through an ankylosed disk or young adults as simply “back pain,” but awareness of a pseudarthrosis. Lateral flexion and extension views of early findings such as lumbar stiffness and decreased the cervical, thoracic, and lumbar spine are essential to lordosis may lead to a correct diagnosis. Positive HLA- identifying instability and ankylosis in patients with B27 assay is present in 80% to 98% of patients with ankylosing spondylitis. ankylosing spondylitis versus 8% of the general popula- tion. Spinal involvement is primarily lumbar at onset 602 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 49 Spondyloarthropathy Computed Tomography and Magnetic Resonance solves but can improve with surgery. In 11 patients with Imaging ankylosing spondylitis and fractures, 6 had neurologic Excellent evaluation of the sacroiliac joints is possible deficits; 3 of 6 patients had improved neurologic func- with CT. Sacroiliac joint space narrowing, erosions, and tion with surgery. Most fractures are unstable because sclerosis are all classically seen on the axial views with- the ankylosis forms a rigid column that does not follow out reconstruction or contrast. Canal stenosis secondary the same three-column criteria of Denis for stability as to the combined effects of kyphosis and ankylosis is well seen in normal spines. The rigid columns act as long defined with MRI. Contrast gives better definition of level arms concentrating forces (such as motion) at the which structures are involved and if spinal cord pathol- fracture site. Epidural hematomas commonly produce ogy is present. neurologic impairment because of the confined rigid ca- nal. Surgery for unstable fractures and epidural hemato- Bone Scan mas is required and combined anterior and posterior The presence of activity in the sacroiliac joints and in approaches and extended fixation must be considered. the spinal column on bone scans may help with the di- Only minor nonstructural fractures should be consid- agnosis of ankylosing spondylitis. Nuclear imaging is an ered stable fractures that can be treated nonsurgically in effective screening tool to identify occult fractures in patients with ankylosing spondylitis. ankylosing spondylitis and should be considered early in the assessment of patients with this disease who sustain Surgical Treatment even minor trauma. There have been reports of devas- tating complications from undiagnosed fractures. Decompression Emergency decompression is indicated for epidural he- Bone Density Studies matomas. Laminectomy is required for cauda equina A decrease in bone density has been shown to be re- syndrome in patients with ankylosing spondylitis. A lated to persistent systemic inflammation in patients study found that 55 patients who had nonsurgical treat- with ankylosing spondylitis. Spinal density measured by ment showed no improvement of sensory, bowel, or dual-energy x-ray absorptiometry (DEXA) increases as bladder deficit; only 2 of these patients had motor im- ankylosis progresses; therefore, DEXA hip measure- provement. ments or quantitative CT should be used. Surgical Indications Osteotomy Extension osteotomy to correct kyphosis at both the Neurologic compromise may be less obvious in patients cervicothoracic junction and lumbar spine is well de- with ankylosing spondylitis than in those with rheuma- scribed in patients with ankylosing spondylitis. Cervical toid arthritis. A recent meta-analysis of 52 articles dis- deformity is best corrected with osteotomy between C7 cussing 86 patients with ankylosing spondylitis and and T1, which is the widest area of the cervical canal cauda equina syndrome showed that nearly all patients and is caudal to the vertebral artery entry at C6. Cervi- had sensory, motor, or reflex deficits on examination cal osteotomies above C7 are rarely required and have a and 30% had previous prostate surgery without im- higher risk of complications. provement for incontinence. Compensations in gait caused by spinal ankylosis may mask the true myelo- Thoracic kyphosis is best treated with extension os- pathic contribution to gait. As myelopathy is associated teotomy at or below L2. Thoracic osteotomies are rarely with rheumatoid arthritis, any myelopathic findings indicated. Patients who have osteotomy at L4 may have should be considered a surgical indication. difficulty sitting on the floor; however, the procedure may need to be considered if two osteotomies are being There are no specific indications for correction of performed. Two levels of osteotomy are recommended chin on chest deformity from cervical kyphosis; how- for deformity greater than 70° and should be separated ever, commonly accepted indications for surgical inter- by one or two levels to distribute the amount of anterior vention include the inability to perform the activities of angulation and distraction. daily living (including those related to personal hy- giene). Correction of thoracolumbar kyphosis was rec- Arthrodesis and Instrumentation ommended if the global kyphosis was greater than 50°, Arthrodesis is required for fractures and after kyphec- or in patients with less severe kyphosis in whom nonsur- tomy. Fusion rates are similar to those seen in the nor- gical management of symptomatic spondylodiskitis was mal spine. Modifications to the standard techniques of unsuccessful. instrumentation may be necessary because of the oblit- eration of bony landmarks that ordinarily serve as refer- Fractures associated with ankylosing spondylitis of- ence points. ten are associated with neurologic deficit that rarely re- American Academy of Orthopaedic Surgeons 603

Spondyloarthropathy Orthopaedic Knowledge Update 8 Surgical Outcomes Kawaguchi Y, Matsuno H, Kanamori M, Ishihara H, Ohmori K, Kimura T: Radiologic findings of the lumbar Correction of kyphosis by posterior subtraction osteot- spine in patients with rheumatoid arthritis, and a review omy has previously been described and reported. In a of pathologic mechanisms. J Spinal Disord Tech 2003;16: recent large series, 92 osteotomies were done in 78 pa- 38-43. tients with mean correction of 34.5% per osteotomy lev- el; the maximum correction attained was 100°. Neither In this study, 106 patients were evaluated by questionnaire deaths nor vascular complications were noted compared and lumbar spine radiographs. A scoring system was used for with previously reported mortality of up to 10% with the radiographs and consensus of significant changes by three anterior opening wedge osteotomy. Loss of correction observers was required. Low back pain was noted by 40% of occurred in only two patients. Patients reported out- the patients and was believed to be severe by 3%. Leg pain come as excellent (83%) or good (15%); one patient and leg numbness were noted in 18% and 14%, respectively. outcome was not reported. Significant radiologic findings were noted in 57% of patients. In order of frequency, these findings were disk space narrow- Annotated Bibliography ing, postural anomaly, olisthesis, end of plate erosion, and facet erosion. End plate erosion correlated closest to clinical symp- Ahn NU, Ahn UM, Nallamshetty L, et al: Cauda equina toms. syndrome in ankylosing spondylitis (the CES-AS syn- drome): Meta-analysis of outcomes after medical and Kurugoglu S, Mihmanli I, Kanberoglu K, Kanberoglu A: surgical treatments. J Spinal Disord 2001;14:427-433. Destructive diskovertebral lesions in ankylosing spondylitis: Appearance on magnetic resonance imag- A case report of acute onset of cauda equina syndrome as- ing. South Med J 2001;94:837-841. sociated with ankylosing spondylitis is presented and a review of 52 articles with 86 patients is evaluated regarding treatment A case report of an 18-year-old woman with initial com- outcome. Onset of symptoms was found to be gradual. Only plaints of back and chest pain is presented. The patient had no 22% of the patients had radicular symptoms, yet nearly all pa- restriction in motion or neurologic symptoms. Diskovertebral tients had some neurologic deficit on physical examination. lesions were found diffusely throughout the spine. Involve- Thirty percent of the male patients had undergone prostatec- ment of the sacroiliac joint was found 6 months later by nu- tomy for misdiagnosed prostatic hypertrophy. Improvement of clear scintigraphy and CT scan. HLA-B27 was positive. sensory, bowel, and bladder dysfunction was not noted with nonsurgical treatment, but in 6 of the 15 patients who had sur- Laiho K, Soini I, Kautiainen H, Kauppi M: Can we rely gery, some form of improvement was shown. Neurologic defi- on magnetic resonance imaging when evaluating unsta- cit progressed much less in the surgically treated group. ble atlantoaxial subluxation? Ann Rheum Dis 2003;62: 254-256. Chen IH, Chien JT, Yu TC: Transpedicular wedge os- teotomy for correction of thoracolumbar kyphosis in Twenty-two patients with rheumatoid arthritis and one pa- ankylosing spondylitis: Experience with 78 patients. tient with juvenile idiopathic arthritis were evaluated for neck Spine 2001;26:E354-E360. pain. Evaluation included flexion and extension lateral cervi- cal spine radiographs and functional cervical spine MRI. The A retrospective study of a single surgeon’s experience is magnitude of anterior atlantoaxial subluxation in flexion was evaluated. Modifications to Thomasen’s original description greater in all patients measured by radiography than by MRI. for closing wedge osteotomy are included. With a mean Seventeen percent of the flexion MRI scans did not show sub- follow-up of 3.8 years, excellent results were noted in 83% of luxation that was seen by radiography. patients and good results in 15%. Only two patients had a loss of correction within the osteotomy segment. Average correc- Matsunaga S, Sakou T, Onishi T, et al: Prognosis of pa- tion of the osteotomy was 34.5º. tients with upper cervical lesions caused by rheumatoid arthritis: Comparison of occipitocervical fusion between Chou LW, Lo SF, Kao MJ, Jim YF, Cho DY: Ankylosing c1 laminectomy and nonsurgical management. Spine spondylitis manifested by spontaneous anterior atlanto- 2003;28:1581-1587. axial subluxation. Am J Phys Med Rehabil 2002;81:952- 955. Treatment of myelopathy secondary to irreducible atlanto- axial dislocation was compared between 19 patients undergo- A case report of spontaneous anterior atlantoaxial sublux- ing C1 laminectomy with occipital cervical fusion and instru- ation is presented. There was no history of trauma or back mentation and 21 matched patients who were treated pain and no alteration of bowel or bladder function. Examina- nonsurgically. All patients were followed until their deaths, tion revealed severe cervical but only mild lumbar spine mo- which averaged 9.7 years in the surgically treated patients and bility limitations. The patient underwent C1 laminectomy and 4.2 years in the nonsurgically treated patients. Pain improved occiput to C2 fusion and fixation and had almost complete with all patients following surgery and neural improvement of resolution of his neurologic symptoms. one or more Ranawat levels was found in 68% with worsening in only 5%. The 10-year survival rate with surgery was 37% and 0% without surgery. 604 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 49 Spondyloarthropathy Reijnierse M, Dijkmans BA, Hansen B, et al: Neurologic Classic Bibliography dysfunction in patients with rheumatoid arthritis of the cervical spine: Predictive value of clinical, radiographic Boden SD, Dodge LD, Bohlman HH, Rechtine GD: and MR imaging parameters. Eur Radiol 2001;11:467- Rhematoid arthritis of the cervical spine: A long term 473. analysis with predictors of paralysis and recovery. J Bone Joint Surg Am 1993;75:1282-1297. Forty-six patients with rheumatoid arthritis for at least 5 years were followed annually with examination, radiographs, Conaty JP, Mongan ES: Cervical fusion in rheumatoid and MRI to correlate neurologic dysfunction with diagnostic arthritis. J Bone Joint Surg Am 1981;63:1218-1227. changes. All patients had a second examination and eight had five sequential examinations. Subjective muscle weakness was Crockard HA: Surgical management of cervical rheu- the only symptom associated with neurologic dysfunction. No matoid problems. Spine 1995;20:2584-2590. significant radiographic abnormalities could be statistically correlated to neurologic dysfunction. The only MRI abnormal- Lipson SJ: Rheumatoid arthritis in the cervical spine. ity that was statistically significant was decreased subarach- Clin Orthop 1989;239:121-127. noid space along the entire cervical spine, which was a subjec- tive interpretation. Morizono Y, Sakou T, Kawaida H: Upper cervical in- volvement in rheumatoid arthritis. Spine 1987;12:721- Sandhu FA, Pait TG, Benzel E, Henderson FC: Occipi- 725. tocervical fusion for rheumatoid arthritis using the inside-outside stabilization technique. Spine 2003;28:414- Neva MH, Kauppi MJ, Kautiainen H, et al: Combination 419. drug therapy retards the development of rheumatoid at- lantoaxial subluxations. Arthritis Rheum 2000;43:2397- The technique using cranial bolts for occipital cervical sta- 2401. bilization is described, and the results in 21 patients who un- derwent a stabilization and fusion are presented. No implant Rana NA: Natural history of atlanto-axial subluxation in complications or failures occurred. Ranawat neurologic level rheumatoid arthritis. Spine 1989;14:1054-1056. improved in 62% of the patients. There was no decline in neu- rologic level immediately following surgery or during the Ranawat CS, O’Leary P, Pellicci P, Tsairis P, Marchisello follow-up period that averaged 25.5 months. P, Dorr L: Cervical spine fusion in rheumatoid arthritis. J Bone Joint Surg Am 1979;61:1003-1010. van Asselt KM, Lems WF, Bongartz EB, et al: Outcome of cervical spine surgery in patients with rheumatoid ar- Santavirta S, Slatis P, Kankaanpaa U, Sandelin J, Laa- thritis. Ann Rheum Dis 2001;60:448-452. sonen E: Treatment of the cervical spine in rheumatoid arthritis. J Bone Joint Surg Am 1988;70:658-667. Various types of cervical fusion in patients with rheuma- toid arthritis and cervical myelopathy and/or occipital neural- Thomasen E: Vertebral osteotomy for correction of ky- gia were followed for 2 years. Mortality at 2 years was 27% phosis in ankylosing spondylitis. Clin Orthop because of a variety of reasons. Of the surviving patients, 73% 1985;194:142-152. had neurologic improvement at 3 months and 67% had an im- proved neurologic level at 2 years. American Academy of Orthopaedic Surgeons 605



Chapter 50 Endoscopic and Minimally Invasive Spine Surgery Eeric Truumees, MD Introduction umn lies centrally in the body. Open surgical approaches involve significant soft-tissue dissection, which affects Minimally invasive and endoscopic spine surgery does risk, recovery, and long-term function. Endoscopically not refer to a single technique, but rather to a set of assisted and mini-open approaches rely on advances in tools in a continuum of less morbid approaches to the surgical lighting, corridor retractors, and image guidance treatment of spine problems. These tools continue to during standard operations with standard instruments to emerge and will ultimately include injection techniques perform spine surgery with less fascial plane violation (epidural injections, diskography, and facet and nerve and dead space creation. root blocks), percutaneous therapeutic modalities (in- tradiskal electrothermal therapy [IDET], vertebroplasty, Most thoracic and lumbar spine procedures are per- and kyphoplasty), true endoscopic procedures (endo- formed posteriorly. Posterior approaches offer relatively scopic diskectomies, endoscopic lumbar fusions, and direct access to the bony elements and the spinal canal. endoscopic transthoracic procedures), image-guided sur- However, canal exposure may result in symptomatic gery, bone substitutes and enhancers, nuclear replace- epidural fibrosis. The dissection and retraction of the ment, and injection of growth factors. paraspinal muscles may lead to dead space formation and extensor muscle disruption. Such disruption has There is no clear delineation between traditional been referred to as fusion disease, which may be associ- and minimally invasive spine surgery. Minimally inva- ated with early fatigability and other long-term symp- sive approaches reflect a trend in orthopaedic surgery to toms. Less invasive posterior techniques may allow for closely target the pathology during a given therapeutic less disruption of the posterior musculature and a intervention while minimizing damage to the surround- smaller laminotomy. ing tissues. Typically, these techniques represent new ways to perform traditional surgical procedures, such as Anterior fusion procedures have become more com- instrumentation and fusion. Occasionally, newer surgical mon in the treatment of symptomatic lumbar disk de- interventions are introduced, such as percutaneous ver- generation, spinal deformity correction, and the ablation tebral body polymethylmethacrylate augmentation. of tumors and infections. Traditional anterior ap- proaches may require large incisions, rib resections, and Surgical indications are not changed by the way in division of major muscle groups. Several endoscopic ap- which the procedure is done. In considering the role of proaches, including transthoracic, transperitoneal, and minimally invasive spine surgery as part of a continuum retroperitoneal approaches, have been described in an of spine care, it is useful to remember that the most effort to limit the morbidity associated with anterior minimally invasive modality remains nonsurgical care. surgical approaches. Nonsurgical treatment is appropriate and effective for most patients with degenerative conditions of the spine, Percutaneous Disk Procedures especially those with axial pain in the absence of neuro- logic dysfunction. For newer technologies, surgical indi- Percutaneous Diskectomy Techniques cations are evolving. Over time, various radiographically guided procedures These newer surgical technologies can be catego- have been developed as both diagnostic and therapeutic rized by the spectrum of invasiveness each requires— interventions that can significantly limit perioperative from truly percutaneous, to endoscopic, to mini-open. risk and morbidity. Chymopapain, a proteolytic enzyme Spinal endoscopy refers to the use of an endoscope and obtained from a papaya extract, has been used as a per- light source for visualization and magnification through cutaneous treatment modality for disk herniations. The small percutaneous portals. Conceptually, endoscopy is enzyme hydrolyzes the nuclear bulge and thereby de- an attractive treatment option because the spinal col- creases nerve root pressure. However, it does not affect American Academy of Orthopaedic Surgeons 607

Endoscopic and Minimally Invasive Spine Surgery Orthopaedic Knowledge Update 8 Table 1 | Fractures Less Likely to Improve With Standard for 17 minutes. Possible goals include collagen fibril Medical Management shrinkage to stabilize the motion segment or destruction of nociceptive fibers. Fractures of thoracolumbar junction (T11-L2) Bursting fracture patterns The published indications for IDET include more Wedge compression fractures with > 30° of sagittal angulation than 6 months of discogenic pain, more than 3 months Vacuum shadow in fractured body (ischemic necrosis of bone) of failed medical treatment and physical therapy, con- Progressive collapse seen in office follow-up cordant diskography, maintenance of at least 50% resid- ual disk height, and the absence of neurocompressive extruded or sequestered fragments. Although good re- pathology. sults continue to be published in the world literature, chymopapain injection has fallen out of favor in North Initial outcomes reports have been highly varied. A America because of complications, including anaphy- designer series of 25 consecutive patients reported a laxis and transverse myelitis. 2-point difference in pain scores at an average follow-up of 7 months. Improvements in the Medical Outcomes Several percutaneous techniques of microdiskec- Study Short Form 36-Item (SF-36) scores for physical tomy have been developed as well. In the 1970s, instru- function and body pain subscales were noted in 72% of mentation was developed to access the disk space per- patients. No complications were reported. A recent up- cutaneously from a posterolateral approach. These date, also by the product’s designers, found that im- procedures were believed to debulk the central disk, provements increased from 1- to 2-year follow-up. These thereby indirectly reducing nerve root irritation and no- and other IDET articles have been criticized for the rel- ciceptor stimulation of the anulus fibrosus. Modifica- atively low hurdle (for example, 2 points on the visual tions of the procedure allowed direct visualization analog scale) that was used to determine significance. through an arthroscope. Like chymopapain injections, Others argue that in the absence of significant complica- these techniques, which continue to be performed at tions, IDET remains a viable modality in a small num- some institutions, are reserved for patients with con- ber of patients. Yet, complications have been reported, tained herniations and bulges. Studies comparing auto- including diskitis and cauda equina syndrome. mated percutaneous diskectomy with open microdiskec- tomy usually demonstrate better results with open Recent basic studies questioned the ability of the microdiskectomy. IDET probe to affect collagen denaturation or nocicep- tive fibers. One biomechanical study showed an increase Endoscopic diskectomy is performed in a manner in motion at the treated segment, raising the possibility nearly identical to open diskectomy, with the exception of long-term destabilization. A recent MRI study found that the surgical instruments are passed through a tubu- no change in the appearance of the high-intensity zone lar retractor. With these systems, a transmuscular rather in degenerated disks after IDET. than subperiosteal approach is undertaken because it is theorized that the smaller incisions will result in re- Vertebral Body Augmentation (Vertebroplasty and duced postoperative pain and improved mobilization. Kyphoplasty) Potential disadvantages with these techniques in- clude limited visualization, a long learning curve during In the United States, approximately 700,000 os- which complications are more frequent, the risk of inad- teoporotic vertebral compression fractures occur each equate exposure or incomplete decompression, the risk year. Traditionally, these fractures were thought to heal of vessel or nerve root damage, limits in the ability to uneventfully with few, if any, sequelae. However, com- treat lateral recess and foraminal stenosis, and difficulty pression fractures represent a serious and growing accessing the L5-S1 disk space from a far lateral ap- health care problem worldwide. Long-term sequelae of proach in some patients (especially male patients with a vertebral compression fractures are common and in- narrow pelvis). clude pain, deformity, pulmonary decline, gastrointesti- nal disturbance, gait and functional decline, and in- Intradiskal Electrothermal Therapy creased mortality. Population studies report that significant functional impairment can occur among peo- Given the mixed outcomes of fusion surgery when treat- ple with vertebral compression fractures who do not ing patients with discogenic back pain, newer modalities seek medical attention. such as thermal energy have been applied to the disk. IDET is conceptually based on the conversion of radio- The pain associated with a given vertebral compres- frequency energy into thermal energy. With fluoroscopic sion fracture is highly variable. Of those patients pre- guidance, a catheter probe is steered along the posterior senting to physicians with pain after a vertebral com- annular wall. Once in place, the tissues are heated to 65° pression fracture, many respond to treatment with narcotic pain medications and bracing. In some patients, bracing is not well tolerated or it does not immobilize the fracture adequately (Table 1). It has been estimated 608 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 50 Endoscopic and Minimally Invasive Spine Surgery Figure 1 A, Preoperative T2-weighted MRI study demonstrating several osteoporotic frac- tures. The healed fracture has a normal mar- row signal, whereas the acute fracture demon- strates increased signal (marrow edema). B, A lateral fluoroscopic image of the same patient undergoing kyphoplasty with balloon reduction of the fracture. C, Postoperative axial CT scans of the treated level show evidence of a well- contained cement mantle. that each year approximately 150,000 patients with com- ture and possible instrument trajectories. In patients pression fractures require hospitalization with pro- who are unable to undergo MRI, a bone scan may esti- tracted periods of bed rest and administration of intra- mate fracture acuity. A CT scan will provide similar venous narcotics. In elderly patients, osteoporosis with morphologic information, particularly when sagittal re- bed rest is associated with an additional 4% loss of bone constructions are ordered. mineral density. Vertebroplasty involves a unilateral or bilateral per- On plain radiographs, vertebral compression frac- cutaneous approach to the vertebral body. Various nee- tures have different configurations. In the thoracic dle and applicator systems are available through which spine, fractures often have a wedge appearance caused liquid polymethylmethacrylate bone cement is intro- by kyphotic loading. In the lumbar spine, central end duced into the vertebral body. The early clinical results plate cupping of lordotic lumbar bodies is seen. These of vertebroplasty suggest that it is effective in decreas- levels are also more likely to demonstrate a bursting ing pain in most patients. However, the mechanism of pattern. It may be difficult to distinguish fracture age pain relief is controversial. Patient groups responding using plain radiographs alone. A sclerotic band below well to these techniques typically have mechanical in- the end plate may represent healing or merely com- competence of their vertebral body. Polymethyl- pressed trabeculae. Comparison with older films (even a methacrylate bone cement restores the load-bearing ca- recent chest radiograph) may help. MRI has a high sen- pacity of the vertebral body. This restoration of stiffness sitivity for fracture acuity, which is reflected by peri– is thought to provide pain relief. A degree of postural end-plate edema and is typically seen as an increased reduction is also possible in some fractures treated with signal on T2-weighted or short T1 inversion recovery vertebroplasty. images (Figure 1). T1-weighted signal intensity is usually diminished. MRI is also used to assess fracture architec- Kyphoplasty extends the vertebroplasty concept. During this procedure, a bilateral approach to the verte- American Academy of Orthopaedic Surgeons 609

Endoscopic and Minimally Invasive Spine Surgery Orthopaedic Knowledge Update 8 Table 2 | Precautions and Contraindications to Kyphoplasty Table 3 | Applications for Video-Assisted Thoracic Spinal and Vertebroplasty Surgery Neurologic symptoms Infection Young patients* Biopsy Pregnancy Débridement High-velocity fractures Drainage of abscess Fractures pedicles or facets Tumor Burst fracture with retropulsed bone Biopsy Medical issues† Tumor excision Allergy to devices Corpectomy and grafting Allergy to contrast medium Degenerative disease Bleeding disorders Excision of herniated thoracic disk Severe cardiopulmonary difficulties Trauma Technically not feasible Corpectomy Vertebra plana Cancellous bone grafting Multiple painful vertebral bodies Deformity Level above T5 Anterior releases for scoliosis or kyphosis Neoplasm Anterior fusion and instrumentation Osteoblastic metastasis Hemivertebra excision Patients with significant long-term survivability Internal thoracoplasty Primary spinal neoplasm Severe cortical destruction Table 4 | Contraindications to Thoracoscopic Spine Surgery Local spinal infection *Age range varies; caution in patients younger than 65 years Inability to tolerate one-lung ventilation †Severe pulmonary problems precluding prone positioning because of vertebral size or Severe or acute respiratory insufficiency High airway pressures with positive pressure ventilation imaging problems Pleural symphysis Bullous lung pathology bral body is made through 1-cm incisions. Cannulas al- Empyema (relative) low introduction of balloon tamponades. Sequential in- Previous thoracotomy (relative) flation of these tamponades creates a void in the Previous tube thoracostomy (relative) cancellous bone of the vertebral body and attempts to Narrow anterior posterior chest diameter (relative) reduce the deformity. The balloon tamponades are then removed. Another theoretic advantage is that viscous possible with kyphoplasty, but it may be variable as a polymethylmethacrylate bone cement can be introduced function of fracture age. into the void for a more controlled fill. Endoscopic and Mini-Open Procedures Vertebral body augmentation should be considered in patients who are bedridden because of pain or in Thoracic Spine those whose pain does not begin to decline after several weeks of nonsurgical care. Results are best for patients Most endoscopic spine surgery is directed anteriorly with focal, intense, deep pain in the midline. Usually, where larger incisions and postthoracotomy pain may pain worsens with activity and is relieved when recum- be avoided. Video-assisted thoracic spinal surgery has bent. The contraindications of vertebral body augmenta- the same indications and goals as open thoracotomy tion are listed in Table 2. (Tables 3 and 4). Vertebral body augmentation procedures are usually Many of these techniques are technically demanding well tolerated. Good to excellent short-term pain relief and are only performed in select centers worldwide. Be- has been reported in more than 80% of patients. Com- fore attempting thoracoscopic approaches to the spine, plications typically occur in association with polymethyl- the surgeon must be thoroughly familiar with open an- methacrylate bone cement extravasation and can lead to terior spinal anatomy and have considerable animal lab- canal compromise or pulmonary embolism. These com- oratory and proctored surgical experience. The largest plications appear to be more common among patients early experience with video-assisted thoracic surgery who undergo vertebroplasty. Additional reduction is has been in patients undergoing treatment for spinal de- 610 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 50 Endoscopic and Minimally Invasive Spine Surgery formities. A thoracoscope can be used to assist anterior Table 5 | Advantages and Disadvantages of Endoscopy release surgery in patients with large kyphotic or scoli- otic deformities. The advantages and disadvantages of Advantages thoracoscopic surgery are listed in Table 5. Less postoperative pain Alleviates the physiologic concerns of healing associated with large Thoracoscopic spinal surgery requires a fluoroscopic table and selective double lumen endotracheal intuba- incisions into the thoracic, peritoneal, or retroperitoneal cavities tion. Surgery proceeds in stages, beginning with the se- Improved visualization of the target tissues lection of access sites. The sixth intercostal space at the Improved cosmetic result with smaller incisions midaxillary line gives an unobstructed view of the entire Reduced recovery time and hospital stay hemithorax. The rib cage and chest wall form a rigid Disadvantages open space in which to work. Unlike laparoscopy, car- Steep learning curve bon dioxide insufflation is not required during thoraco- Cost scopic spinal surgery. Limitations in tactile feedback Increased working distance from 4 to 30 cm Instruments are centered at the level of the pathol- Two-dimensional video visualization ogy. The lung may require retraction with an endoscopic Triangulation fan retractor or strategically placed sponges. Once the Limited depth perception level of the pathology has been identified, the parietal Necessity for specialized instruments pleura is incised. The parietal pleura is bluntly dissected Adverse effect on ability to deal with certain complications (such as proximally, distally, and anteriorly to expose as much of the vertebral margins as necessary. brisk arterial bleeding) As experience is gained, disadvantages much less limiting After the anulus fibrosus is incised with cautery, the disk and cartilage end plates are removed to bleeding be completed by negotiating allograft struts or mesh bone with long pituitaries, Cobb elevators, and curets. cages into the defect after inserting them into the chest For patients undergoing kyphosis correction, the ante- through an enlarged portal. rior longitudinal ligament and opposite side of the anu- lus fibrosus is incised. In patients undergoing releases Techniques for endoscopic transthoracic spinal in- for the treatment of scoliosis, it is mandatory to incise strumentation continue to evolve with the development the posterolateral corner of the disk spaces in the con- of new implants capable of stabilization and correction. cavity of the curve. Morcellized rib or iliac crest graft Threaded cylindrical interbody fusion cages, in wide- can be delivered by a funnel or a structural graft (femo- spread use in the treatment of deformities of the lumbar ral ring allograft or cage) delivered through an enlarged spine, are now being used to treat deformities of the portal. thoracic spine in the coronal or oblique plane. Such tho- racic cage application may be technically less demand- In certain patients, a thoracoscopic release, with the ing, but the consequences of malpositioning are signifi- patient in the prone position, may be done concurrently cant. The fusion rates for patients with single thoracic with open posterior stabilization. Similarly, internal tho- cages have yet to be evaluated. Existing posterior or an- racoplasty may also be performed concurrently or as an terior rod and screw implant systems have been modi- independent procedure. Rib resections are planned as fied for application in an endoscopic fashion. an ellipse to ensure smooth chest contours. The perios- teum of the rib portion to be resected is stripped, and a Increasingly, open and endoscopic approaches are high-speed burr creates the osteotomy. being combined for instrumentation. In such proce- dures, one of the portals is enlarged to a 5-cm incision, Patients with symptomatic thoracic disk herniations which allows the use of more standard surgical instru- may be amenable to treatment with endoscopic trans- ments and significantly simplifies implant introduction. thoracic decompressions. Patient selection is a critical is- sue because patients rarely have true radicular or my- In the postoperative period, most patients are extu- elopathic symptoms. Patients with diffuse midthoracic bated immediately. A chest tube is maintained at water back pain and diagnostic imaging showing evidence of seal and removed 1 to 2 days postoperatively. An inten- multiple degenerative segments with or without hernia- sive care unit stay is not usually needed. Aggressive res- tions are not good candidates for either open or endo- piratory care is required to prevent “down lung” scopic diskectomy. atelectasis and pneumonia. Comparable endoscopic techniques have been de- Complications of thoracoscopic surgery are essen- scribed for vertebral corpectomies or osteotomies. The tially the same as with an open approach. As in any spi- spine is exposed by bluntly dissecting the pleura and li- nal cord level procedure, spinal cord injury or ischemia gating only those segmental vessels in the surgical field. is possible. Dural laceration may be noted. Intercostal A combination of pituitary rongeurs, curets, Cobb eleva- tors, and high-speed burrs are used as they would be with the chest open. The corpectomy reconstruction can American Academy of Orthopaedic Surgeons 611

Endoscopic and Minimally Invasive Spine Surgery Orthopaedic Knowledge Update 8 neuralgia is common (21% of patients), but it is usually interbody fusion techniques, have been described and transient. Endoscopic releases may be less complete are marketed with specialized instruments by the vari- than open releases. Also, trocar or instrument injury to ous implant manufacturers. Long-term results of fusions the lung, diaphragm, heart, great vessels, thoracic duct, with these implants are not yet available. azygos vein, esophagus, segmental arteries, sympathetic chain, and splanchnic nerves is possible. Interestingly, much of the current interest in percuta- neous pedicle screw technology comes from the in- One series compared video-assisted thoracoscopic creased use of anterior lumbar interbody cages, them- surgery to open thoracotomy in a sheep model. In this selves part of the vanguard of minimally invasive spine series, histologic, biomechanical, and radiographic out- surgery. Increasingly, the late instability of fusion con- comes were comparable to those of open surgery. How- structs resulting from the use of these threaded fusion ever, endoscopic procedures were associated with pro- cages in motion segments with preserved disk height has tracted learning periods, long surgical times, increased been described. Additionally, posterior stabilization has blood loss, and increased animal morbidity. Others re- been recommended. Translaminar facet screws repre- port that, with increased surgeon experience with these sent another method of achieving posterior fixation procedures, tissue damage, blood loss, postoperative through small incisions with minimal tissue stripping. pain, intensive care unit and hospital stays are reduced and that respiratory and shoulder function are less af- Most truly endoscopic lumbar spine procedures are fected. anterior. Unlike the posterior approach, there are sev- eral critical anatomic structures that must be avoided Lumbar Spine when approaching the spine anteriorly, including the in- ferior epigastric artery and vein, which lie deep to the Several methods have been described to reduce the ex- surface of the rectus muscle. Placement of endoscopic posure needed for posterior decompression surgery. The ports through these structures is associated with postop- most common is use of a surgical microscope. Microdis- erative hematoma formation. The ureters run obliquely kectomy is the most commonly performed minimally in- from the retroperitoneal space into the abdomen. The vasive approach to partial disk removal (see chapter left ureter runs obliquely in the mesentery deep to the 44). sigmoid and is not usually seen. The right ureter runs obliquely over the right iliac into the pelvis and may oc- A newer endoscopic diskectomy technique uses a tu- casionally be injured. The ureter will sometimes course bular working cannula. The fiberoptic image bundle is in midline directly over the L5-S1 disk space and may housed in a sidewall of the cannula. Standard instru- be directly damaged by surgical exposures. Overretrac- ments, such as pituitary or Kerrison rongeurs, are in- tion of the psoas muscle may injure the lumbar plexus. serted under direct vision. This technique has also been Injury to the lumbar sympathetic chain, just anterior to used to treat cervical disk herniations (via lamino- the L5-S1 disk, may result in retrograde ejaculation. foraminotomy) and for microdecompression of lateral recess lumbar spinal stenosis. The benefits of this tech- Contraindications to anterior spinal endoscopic sur- nique over the more traditional microdiskectomy have gery include peritoneal or pelvic infections, prior open not yet been established. For most spine surgeons, mi- anterior spine surgery, or prior lower abdominal surgery crodiskectomy remains the safer technique. (such as colon resection or hysterectomy). Endometrio- sis also causes adhesions that can limit anterior spinal The role of posterior endoscopic and minimally in- endoscopy. vasive techniques in the treatment of metastatic disease, fractures, and infections is evolving. Although the ante- Anterior spinal endoscopy can be performed with or rior approach to metastatic disease is favored overall, without insufflation. Insufflation involves the use of car- the use of an endoscope to assist posterolateral decom- bon dioxide to inflate the abdominal cavity to more pression may obviate the need for a second anterior sur- completely visualize surrounding anatomic structures. gery in patients undergoing posterior stabilization. Insufflated surgery is a direct extension of conventional laparoscopic surgery. It gives direct access to L5-S1, The medial branch of the dorsal primary ramus can L4-5, and occasionally to L3-4. The advantages of insuf- be injured when a midline approach is carried beyond flation include organ retraction, more rapid exposure, the facets and over the transverse processes. To mini- increased working space, and decreased bleeding. How- mize this type of injury, several newer techniques have ever, special instruments are required, including expen- been developed that use a muscle-splitting approach in sive trocars with diaphragms. Additionally, air may leak the interval between the multifidus medially and the during the procedure. Moreover, carbon dioxide insuf- longissimus laterally. This approach is similar to that de- flation of the peritoneal cavity increases mean arterial scribed by Wiltse for far lateral diskectomy. Exploiting pressure and decreases venous return. Carbon dioxide this plane, endoscopic, fluoroscopic, or navigation sys- absorption may lead to hypercapnia and decreased dia- tem assistance allows for transpedicular instrumentation phragmatic excursion. Carbon dioxide embolism from through smaller incisions. Several variations, including open veins has also been reported. 612 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 50 Endoscopic and Minimally Invasive Spine Surgery Figure 2 A, Photograph of the introduction of a working portal during thoracoscopy. B, Photograph of the initial thoracoscopic approach to the disk space. With a gasless approach, the anatomic approach re- firmed on fluoroscopy (Figure 2). mains the same, but the working space is created by lift- The retroperitoneal approach uses a potential space ing the anterior abdominal wall with a fan retractor and hydraulic arm (Laparolift, Origin Medsystems, Menlo behind the peritoneal sac. Advantages of this approach Park, CA). This technique decreases costs because con- include improved spinal access from T12 to S1. In that ventional instruments are used. However, gasless sur- the peritoneum contains the bowel loops, retraction is gery takes longer and is technically more difficult to facilitated. Additionally, conventional instruments may perform. Moreover, lateral vision is limited with the use be used and conversion from a pure percutaneous endo- of this technique. A combined approach using insuffla- scopic to an endoscopically assisted anterior approach tion for the initial spine exposure to place retractors and may be performed if increased difficulty is encountered. Steinmann pins and the subsequent conversion to a gasless/Laparolift procedure falls in the midrange in In retroperitoneal approaches, a left lateral decubi- terms of cost and ease of use. tus positioning of the patient allows abdominal contents to fall freely forward. A skin incision is made, the inter- Operating room positioning of the patient is critical nal and external obliques are identified, and fibers are for these procedures. Drains including a Foley catheter spread bluntly. This exposes the transversalis fascia, and nasogastric tube are placed. The patient is supine which is also incised. A finger may be used to bluntly with one or both arms tucked at the side or overhead dissect in the retroperitoneal space along the twelfth rib (for fluoroscopic control). Steep Trendelenburg posi- to the transverse process of T12 or L1. The potential tioning is often required; therefore, a special shoulder space may be increased by inserting an insufflating bal- harness or foot stirrups may also be needed. Fluoros- loon or a gasless technique with a Laparolift or insuf- copy and endoscopy monitors must be in the direct line flated technique may be used. The blunt dissection is of sight of spine and endoscopic surgeons. The prepara- carried posteriorly to the psoas fibers until the disk tion materials and drape must allow for bone graft har- space is identified. vest and conversion to an open procedure, if necessary. Titanium cage or bone dowel implantation, which is The actual approach to the spine may be transperi- among the most commonly performed lumbar endo- toneal or retroperitoneal. In transperitoneal endoscopy, scopic techniques, is typically used for anterior column the procedure begins with placement of the first (umbil- fusion in patients with disk-related pain (Figure 3). Ad- ical) portal. Once in place, the peritoneum is insufflated vantages include avoidance of extensor muscle strip- to 15 mm with carbon dioxide. Secondary ports are then ping, more rigid anterior fusion, and lower pseudarthro- placed under visual guidance, including a 17-mm supra- sis rates from grafting under compression. Reports of pubic working portal. A superficial incision in the mid- failure of these implants as stand-alone devices have line peritoneum from the sacral promontory to vascular dimmed the initial enthusiasm. bifurcation is made, exposing the spine. Blunt dissection in the retroperitoneal space is used to identify the mid- The implementation of endoscopic approaches to dle sacral artery and the several medial branches of the the anterior spine has fostered a renewed interest in de- iliac veins, which are clipped. More blunt dissection will creasing the morbidity of traditional open anterior pro- expose the disk spaces, the levels of which are con- cedures. Various mini-open anterior paramedian muscle- sparing approaches to the lumbar spine have been recently described. Proponents argue that this cosmeti- American Academy of Orthopaedic Surgeons 613

Endoscopic and Minimally Invasive Spine Surgery Orthopaedic Knowledge Update 8 Figure 3 Postoperative AP radiograph of a patient who underwent endoscopic additional costs may be recouped with earlier patient transperitoneal titanium BAK cage (SpineTech, Minneapolis, MN) placement followed discharge, the potential benefits of a minimal approach by open posterior translaminar facet screw instrumentation. are not going to be realized by every surgeon. Because endoscopic approaches limit visualization with a limited cally acceptable approach allows better tactile feedback field width, decreased three-dimensional perspective, and overall safety than endoscopic techniques. In sev- and a loss of tactile sense, surgeons should be prepared eral centers, the initial enthusiasm for endoscopic tech- for immediate conversion to an open procedure if nec- niques has gradually given way to a reversion toward essary. open surgery, but with far more attention given to cos- metics and the minimization of soft-tissue injury. Endoscopic procedures will likely be performed more commonly in the future. Current indications for Summary endoscopic spine surgery include minimally invasive ac- cess to the intervertebral disk (both anteriorly and pos- Most minimally invasive spine surgery involves a change teriorly), débridement of tumor and infection, releases in approach, not a change in the surgical procedure it- for deformity, and anterior interbody fusions. Placement self. Therefore, the indications for surgical intervention of spinal instrumentation anteriorly remains under eval- should not be relaxed merely because these procedures uation. All of these procedures are at risk for achieving may be performed endoscopically. As in any spine sur- overzealous acceptance before independent, random- gery, careful patient selection is paramount in predicting ized studies are done to demonstrate comparable out- successful outcomes. Few long-term data are available comes and risk profiles with accepted techniques. for any of these endoscopic spine surgery techniques. Although many of these procedures are promising, sig- Annotated Bibliography nificant advantages over previous techniques have yet to be demonstrated. Percutaneous Disk Procedures The advantages of endoscopic spinal surgery (im- Biyani A, Andersson GB, Chaudhary H, An HS: Intra- proved surgical visualization through magnification and discal electrothermal therapy: A treatment option in pa- lighting, decreased perioperative morbidity, and short- tients with internal disc disruption. Spine 2003;28:S8- ened hospital stays) must be counterbalanced with the S14. steep learning curve for this procedure. Initial experi- ence with endoscopic spinal surgery may be associated This review of the histologic, biomechanical, and clinical with higher complication rates and longer operating results of IDET suggests that although the mode of effect is times. A less efficacious technique should not be used not understood, IDET may be beneficial in some patients. In merely because it is endoscopic. those who did not have improvement of symptoms, little pro- cedural risk was encountered. Endoscopic spine surgery techniques are also both personnel and equipment intensive. Unlike open proce- Cohen SP, Larkin T, Abdi S, Chang A, Stojanovic M: dures, a second surgeon may be needed for an endo- Risk factors for failure and complications of intradiscal scopic procedure (to perform a second approach). Spe- electrothermal therapy: A pilot study. Spine 2003;28: cialized and usually disposable instruments are also 1142-1147. required for endoscopic spine surgery. Although these In this retrospective review of 79 patients undergoing IDET, 48% of patients reported more than 50% pain relief at 6-month follow-up. In this series, there was a 10% complica- tion rate, but most of the complications were transient and self-limited. Obesity was a risk factor for failure of the proce- dure. Freedman BA, Cohen SP, Kuklo TR, Lehman RA, Lar- kin P, Giuliani JR: Intradiscal electrothermal therapy (IDET) for chronic low back pain in active-duty sol- diers: 2-year follow-up. Spine J 2003;3:502-509. In this consecutive case series assessing the use of IDET in the management of chronic discogenic low back pain in 36 sol- diers, 50% or greater pain reduction was reported by 47% of patients at 6-month follow-up and 16% at 2-year follow-up. The authors also reported that 20 of 31 soldiers (65%) had a persistent decrease in their analog pain scores. Additionally, 7 of 31 soldiers (23%) went on to undergo spinal surgery within 24 months of undergoing IDET. The authors noted that their reasonable early results diminished with time and that up to 614 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 50 Endoscopic and Minimally Invasive Spine Surgery 20% of patients reported worsening of baseline symptoms at gery: An intraoperative EMG study. Eur Spine J 2002; final follow-up. They concluded that IDET should not be used 11:20-26. as a substitute for spinal fusion in the treatment of chronic dis- cogenic low back pain in active-duty soldiers. This electromyographic study demonstrated that less me- chanical irritation of the nerve root occurred with endoscopic Lieberman IH, Dudeney S, Reinhardt MK, Bell G: Ini- approaches than with traditional open surgery. tial outcome and efficacy of “kyphoplasty” in the treat- ment of painful osteoporotic vertebral compression Spruit M, Jacobs WC: Pain and function after intradiscal fractures. Spine 2001;26:1631-1638. electrothermal treatment (IDET) for symptomatic lum- bar disc degeneration. Eur Spine J 2002;11:589-593. This is a prospective study of kyphoplasty procedures that were performed in 30 patients. The results demonstrate excel- This small series of prospectively evaluated patients failed lent outcomes and low complications. to show significant improvement of patient symptoms after undergoing IDET. Lindsay R, Silverman SL, Cooper C, et al: Risk of new Yeung AT, Tsou PM: Posterolateral endoscopic excision vertebral fracture in the year following a fracture. for lumbar disc herniation: Surgical technique, outcome, JAMA 2001;285:320-323. and complications in 307 consecutive cases. Spine 2002; 27:722-731. This article reviews the clinical consequences of vertebral compression fractures and largely dispels the notion that these In this retrospective review of 1-year outcomes in 307 con- injuries follow a benign, self-limited course. secutive patients with lumbar disk herniation who underwent posterolateral endoscopic diskectomy, the response rate to the Muramatsu K, Hachiya Y, Morita C: Postoperative mag- questionnaire was 91%, and 90.7% of those patients reported netic resonance imaging of lumbar disc herniation: being satisfied with their surgical outcomes. The combined ma- Comparison of microendoscopic discectomy and Love’s jor and minor complication rate was 3.5%. method. Spine 2001;26:1599-1605. Endoscopic and Mini-Open Procedures The authors of this study compared postoperative MRI studies and found that the effect of microendoscopic diskec- Anand N, Regan JJ: Video-assisted thoracoscopic sur- tomy on the cauda equina was comparable to that of open disk- gery for thoracic disc disease: Classification and out- ectomy. Furthermore, the postoperative images of the route of come study of 100 consecutive cases with a 2-year mini- entry failed to show that microendoscopic diskectomy is ap- mum follow-up period. Spine 2002;27:871-879. preciably less invasive with respect to the paravertebral mus- cles. In this retrospective review of prospectively collected 4-year follow-up data in 100 consecutive patients who under- Phillips FM, Ho E, Campbell-Hupp M, McNally T, Todd went video-assisted thoracoscopic surgery, no permanent com- Wetzel F, Gupta P: Early radiographic and clinical re- plications or spinal cord injuries were reported. The average sults of balloon kyphoplasty for the treatment of os- percentage of improvement in Oswestry scores was most sig- teoporotic vertebral compression fractures. Spine 2003; nificant in grade 4 patients (myelopathy, 60%), followed by 28:2260-2265. grade 3A patients (axial and thoracic radicular pain, 37%), grade 3B patients (axial with leg pain, 28%), and grade 1 pa- This is an outcomes report of 29 patients who underwent tients (pure axial, 24%). The authors concluded that the proce- kyphoplasty in 37 separate sessions; a total of 61 vertebral dure was associated with significant clinical improvement in compression fractures were treated. In 30 of the 52 fractures most treated patients. that were considered reducible, a mean 14.2° of correction was noted. Significant pain relief was noted with minimal compli- Escobar E, Transfeldt E, Garvey T, Ogilvie J, Graber J, cations. Schultz L: Video-assisted versus open anterior lumbar spine fusion surgery: A comparison of four techniques Saal JA, Saal JS: Intradiscal electrothermal treatment and complications in 135 patients. Spine 2003;28:729- for chronic discogenic low back pain: Prospective out- 732. come study with a minimum 2-year follow-up. Spine 2002;27:966-973. This is a retrospective report comparing the outcomes of anterior lumbar interbody fusion in 135 patients using one of This 2-year follow-up study of the original designer series the following four approaches: transperitoneal endoscopy with demonstrated that the statistically significant improvement in insufflation, retroperitoneal endoscopic surgery, mini-open pain scores and SF-36 quality of life scores that was previously surgery, or traditional open approaches. The incidence of com- reported increased between the 1- and 2-year observation plications for video-assisted techniques was found to be con- points. sistent with that reported in the medical literature, but it was higher than that for open techniques. The authors note that Schick U, Döhnert J, Richter A, König A, Vitzthum HE: they no longer use video-assisted techniques as a result of Microendoscopic lumbar discectomy versus open sur- these findings. American Academy of Orthopaedic Surgeons 615

Endoscopic and Minimally Invasive Spine Surgery Orthopaedic Knowledge Update 8 Khoo LT, Beisse R, Potulski M: Thoracoscopic-assisted CT scan fusion rate at 2-year follow-up was 16.6% and was treatment of thoracic and lumbar fractures: A series of deemed unacceptably low. 371 consecutive cases. Neurosurgery 2002;51(5 suppl): 104-117. Classic Bibliography In this report of 371 patients with thoracic and thora- Do HM: Magnetic resonance imaging in the evaluation columbar spine fractures who were treated with thoracoscopic of patients for percutaneous vertebroplasty. Topics in assistance, the severe complication rate was low (1.3%), with MRI 2000;14:235-244. only one instance of each of the following reported: aortic in- jury, splenic contusion, neurologic deterioration, cerebrospinal Grados F, Depriester C, Cayrolle G, et al: Long-term ob- fluid leak, and severe wound infection. servations of vertebral osteoporotic fractures treated by percutaneous vertebroplasty. Rheumatology (Oxford) Pellisé F, Puig O, Rivas A, Bagó J, Villanueva C: Low fu- 2000;39:1410-1414. sion rate after L5-S1 laparoscopic anterior lumbar inter- body fusion using twin stand-alone carbon fiber cages. McLain RF: Endoscopically assisted decompression for Spine 2002;27:1665-1669. metastatic thoracic neoplasms. Spine 1998;23:1130-1135. This study reported prospective data on 12 patients under- Silverman SL: The clinical consequences of vertebral going twin, stand-alone anterior cage placement. Although sig- compression fractures. Bone 1993;13:S27-S31. nificant improvements in visual analog scores, Prolo scores, and Waddell Disability Index scores were noted, the overall 616 American Academy of Orthopaedic Surgeons

Chapter 51 Spinal Cord Injury Kevin C. O’Connor, MD Eric K. Mayer, MD Mitchel B. Harris, MD Introduction Over the past 20 years, tetraplegia has become less common and paraplegia more common. Approximately Over the past two decades, advances in spinal cord med- one half of all traumatic SCIs in the United States are icine have come about at an unprecedented pace. To cervical lesions, and one third are thoracic. The most stay abreast of these advances, it is helpful to review common neurologic level of injury is C5, followed by characteristics of the population affected by spinal cord C4, and then C6. The most common level of paraplegia injury (SCI), their prognosis, testing procedures, and is T12. There has also been a trend toward an increased major medical and rehabilitation sequelae that are stan- number of incomplete lesions (Figure 3). dards of care. Epidemiology Causes of Death The annual incidence of SCI in the United States, not Overall, 85% of SCI patients who survive the first 24 including fatalities at the site of injury, is approximately hours after injury are still alive 10 years later. The most 40 cases per million population, or approximately 11,000 common cause of death is diseases of the respiratory new cases per year. The number of Americans with SCI system, with most of these resulting from pneumonia. has been estimated to be between 183,000 and 230,000. The second leading cause of death following SCI is SCI primarily affects young adults with an average age nonischemic heart disease. Deaths resulting from exter- of injury of 32.1 years; 55% of all SCIs occur in people nal causes such as subsequent unintentional injuries and between the ages of 16 to 30 years, during the most pro- suicides and homicides (but not including multiple inju- ductive working/earning years. The average age of injury ries sustained during the original accident) are the third has been increasing since the 1970s, mirroring the in- leading cause of death. The majority of these deaths are crease in the median age of the general population. The the result of suicide. The fourth leading cause of death is fastest growing cohort with SCI is patients older than infectious and parasitic diseases (usually septicemia as- age 60 years, who now represent 10% of new SCI pa- sociated with decubitus ulcers, urinary tract or respira- tients. There remains a 4:1 male to female ratio that has tory infections). Mortality rates are significantly higher largely remained unchanged since the 1960s. during the first year after injury than during subsequent years. A significant trend has been observed in the racial distribution of patients with SCI. Since 1990, African- Classification Americans and Hispanics have become disproportion- ately affected with new SCIs. Percentages of new SCIs In 1969, Frankel and associates described a five-grade have risen for African-Americans from 5.7% in 1974 to system for classifying traumatic SCI, divided between 27.6% in 1990, and for Hispanics from 5.7% to 7.7%. complete and incomplete injuries. The amount of pre- During the same time period, the percentage of Cauca- served motor or sensory function determined the spe- sians with new SCIs has decreased from 77.5% to 59.1% cific Frankel classification. The Frankel classification (Figure 1). was replaced in 1992 by the American Spinal Injury As- sociation (ASIA) Impairment Scale, which was revised Motor vehicle crashes still account for the largest in 1996, and again in 2000. These standards subsequently percentage of SCIs at a current rate of 38.5%, followed became known as the International Standards for Neu- by acts of violence (mostly gunshot wounds), falls, and rologic and Functional Classification of Spinal Cord In- sports-related injuries (Figure 2). The proportion of in- jury. The ASIA standards have gained widespread ac- juries from falls and acts of violence has increased ceptance as the preferred classification system for SCI. steadily. The initial neurologic examination serves as a baseline American Academy of Orthopaedic Surgeons 619

Spinal Cord Injury Orthopaedic Knowledge Update 8 Figure 1 Racial distribution of SCI. Figure 2 Etiology of SCI since 1990. Figure 3 Current percentage of injuries by ASIA classification (since 1991). for evaluation over the first hours to days after injury; on the face. The sensory level is the most caudal der- however, neurologic status can change over the first few matome to have intact (2/2) sensation for both pinprick days and is influenced by resuscitative procedures. The and light touch on both sides of the body. period from 72 hours to 1 week after injury is the earli- est time period after injury when detailed neurologic The ASIA motor examination consists of testing 10 evaluations can reliably be performed to predict neuro- key muscles (5 in the upper limb and 5 in the lower logic recovery. limb) on each side of the body (Table 1). The patient is supine during testing and strength is graded on a six- The ASIA sensory examination consists of 28 key point scale from 0 to 5. The motor level is defined as the dermatomes, each separately tested for pinprick/dull lowest key muscle that has a grade of at least 3, pro- (with a safety pin) and light touch (with cotton) sensa- vided that the segments above that level are graded as tion on both sides of the body. A three-point scale from 5. Grade 4 is not considered normal, as it previously 0 to 2 is used, with the face serving as the normal refer- was, unless the examiner judges that certain factors in- ence point. A score of 0 represents absent sensation, in- hibited full effort, including pain, positioning, disuse, or cluding inability to distinguish the sharp and dull edge hypertonicity. In patients in whom there is no key mus- of the pin; a score of 1 represents impaired sensation, in- cle for a segment that has intact sensory dermatomes cluding hyperesthesia; and a score of 2 is given when the (C2-C4, T2-L1, and S2-S5), the sensory level defines the pin or cotton is felt in the same manner as when tested motor level. 620 American Academy of Orthopaedic Surgeons

Orthopaedic Knowledge Update 8 Chapter 51 Spinal Cord Injury Table 1 | Key Muscle Groups Involved in ASIA Motor Table 2 | ASIA Impairment Scale Examination A = Complete. No motor or sensory function is preserved in the sacral Root Level Muscle Group Root Level Muscle Group segments S4-S5. B = Incomplete. Sensory but no motor function preserved below the C5 Elbow flexors L2 Hip flexors neurologic level and includes the sacral segments S4-S5. C = Incomplete. Motor function is preserved below the neurologic level, C6 Wrist extensors L3 Knee extensors and more than half of the key muscles below the neurologic level have a muscle grade less than 3. C7 Elbow extensors L4 Ankle dorsiflexors D = Incomplete. Motor function is preserved below the neurologic level, and at least half of the key muscles below the neurologic level have a C8 Long finger flexors L5 Long toe extensor muscle grade greater than or equal to 3. E = Normal. Sensory and motor functions are normal. T1 Small finger abduc- S1 Ankle plantar flexors A is a complete injury, while B through E represent incomplete injuries. For an individual to tors receive a grade of C or D, the injury must be incomplete and have either voluntary anal contraction or sparing of motor function more than three levels below the motor level The skeletal level of injury is defined as the spinal level where, by radiographic examination, the greatest Spinal Cord Injury Syndromes vertebral damage is found. The neurologic level of in- jury is the most caudal level at which both motor and Central Cord Syndrome sensory modalities are intact on both sides of the body. Because of a poor correlation between vertebral injury The most common of the incomplete syndromes is cen- and function, the neurologic level of injury is preferred. tral cord syndrome, which is characterized by motor Because these levels can be different from side to side, weakness of the upper extremities greater than the up to four levels (right C6 sensory, left C8 sensory, right lower extremities, in association with sacral sparing. C5 motor, left C8 motor) may be needed to present a Central cord syndrome most frequently occurs in older clearer picture of the patient’s status. patients with cervical spondylosis and a hyperextension injury, but can occur in any age group or with any mech- Tetraplegia, previously called quadriplegia, is defined anism. The mechanism of injury involves compression of as impairment or loss of motor or sensory function in the cord during hyperextension, caused by an inward the cervical segments of the spinal cord caused by dam- bulging of the ligamentum flavum on an already nar- age of the neural elements within the spinal cord. Tetra- rowed canal. plegia results in impairment of function of the arms as well as the trunk and legs. Paraplegia refers to impair- Central cord syndrome has a typical pattern of re- ment of motor or sensory function in the thoracic, lum- covery that begins with the lower extremities, followed bar, or sacral segments of the spinal cord secondary to by bowel and bladder function, proximal upper extremi- damage of the neural elements within the spinal cord. ties, and hand function. The prognosis is dependent on Paraplegia results in impairment of the trunk and legs, the patient’s age, with those younger than age 50 years depending on the level of injury, but the arms are having a much better prognosis for independence than spared. Plexus injury or injury to the peripheral nerves older patients. However, for patients with ASIA D tet- outside the neural canal are not included. The terms raplegia, the prognosis for recovery of independent am- quadriparesis and paraparesis are discouraged because bulation is excellent, even for those older than age 50 they imprecisely describe incomplete lesions. years. Complete injury is defined as the absence of sensory Brown-Séquard Syndrome or motor function in the lowest sacral segments, and in- complete injury is defined as preservation of motor or Brown-Séquard syndrome involves hemisection of the sensory sensation below the neurologic level of injury spinal cord and accounts for 2% to 4% of all traumatic that includes the lowest sacral segments, also known as SCIs. Neurologically, there is an ipsilateral loss of posi- sacral sparing. Sacral sparing is tested by light touch and tion, light touch, vibration, and motor loss, and a con- pinprick at the anal mucocutaneous junction (S4-5 der- tralateral loss of pain and temperature below the level matome) on both sides, as well as by testing for volun- of the lesion. Neuroanatomically, this is explained by the tary anal contraction and deep anal sensation. If any of crossing of the spinothalamic tracts at the spinal cord these sensations is present, even if impaired, the patient level and the crossing of the corticospinal and dorsal has an incomplete injury. The zone of partial preserva- columns at the medulla. tion refers to those dermatomes and myotomes caudal to the neurologic level that remain partially innervated Overall, patients with Brown-Séquard syndrome and is used only in complete injuries. The ASIA Impair- have the best prognosis for functional outcome and po- ment Scale describes five levels of SCI severity tential for ambulation. Approximately 75% to 90% of (Table 2). American Academy of Orthopaedic Surgeons 621