Simons Myofascial Pain & Dysfunction-The Trigger Point Manual Vol 2-The Lower Extremities

Chapter 9 / Gluteus Minimus Muscle 183 Figure 9.8. Self-stretch of the anterior fibers of the heel. Following 5 seconds of balanced pressure (large right gluteus minimus muscle. The dotted line identi- arrows), or after simply holding the weight of the thigh fies the posterior and the superior borders of the glu- against the pull of gravity, the person relaxes and al- teus minimus muscle; these borders are closely re- lows the right leg to drop downward over the edge of lated to the greater trochanter (open circle), and to the the table. This movement into adduction takes up the crest of the ilium (solid line). A, starting position. The slack and lengthens the anterior part of the muscle. B, individual contracts the muscle gently to press the final stretch position after several cycles of the proce- right leg upward against resistance provided by the left dure described in A. Activities that impose unaccustomed posterior gluteus minimus TrPs; this is stress on the muscle, such as vigorous shown in Figure 8.9 of the previous chap- sports and hiking, should either be ter. The patient can use body weight to avoided or be trained for by incremental achieve deep pressure precisely on these conditioning. gluteus minimus TrPs. Home Therapeutic Program The response to this ischemic compres- sion on the posterior TrPs is enhanced if The patient frequently benefits by learn- the patient slides the buttock over the ten- ing to use a tennis ball for self-application nis ball slowly to produce a stripping mas- of ischemic compression to anterior and sage. This is done by placing the ball under the tender area closest to the greater

184 Part 1 / Lower Torso Pain trochanter, and sliding the body slowly in 2. Ibid. (Fig. 4 - 2 4 ) . a downward direction. The tennis ball 3. Ibid. (Fig. 4 - 4 1 ) . should roll slowly at a rate of about 2.5 cm (1 in) every 10 seconds toward either the 4. Banerjee T, Hall CD: Sciatic entrapment neurop- iliac crest or the sacrum, following the di- athy. J Neurosurg 4 5 : 2 1 6 - 2 1 7 , 1 9 7 6 . rection of the gluteus minimus fibers. This rolling technique may be accomplished 5. Basmajian JV, Deluca CJ: Muscles Alive, Ed. 5. more readily by leaning against a smooth wall than by lying on the floor. Three rep- Williams & Wilkins, Baltimore, 1985 (pp. 3 1 6 - etitions are sufficient at one session. It is wise to follow the stripping massage 317, 381). promptly with moist heat. This therapy 6. Bullock RG: Treatment of Sciatica (letter). Br may be repeated daily until the TrP ten- derness disappears, or every other day if Med J 282:70-71, 1981. local soreness develops. 7. Carter BL, Morehead J, Wolpert SM, et al.: Cross- A self-stretch that is effective for inacti- Sectional Anatomy. Appleton-Century-Crofts, New vating anterior gluteus minimus TrPs is il- lustrated and described in Figure 9.8. This York, 1977 (Sects. 36-40, 44-46). should be coordinated with respiration so 8. Clemente CD: Gray's Anatomy of the Human Body, that the patient inhales during the isomet- ric contraction phase and exhales during American Ed. 30. Lea & Febiger, Philadelphia, the relaxation phase.27 The position illus- trated in Figure 9.6A. also can be employed 1985 (p. 568). with this contraction-relaxation technique. 9. Ibid. (p. 1236). In this case, the contraction during inhala- 10. Duchenne GB: Physiology of Motion, translated by tion should support the weight of the lower extremity without lifting it. During E.B. Kaplan. J. B. Lippincott, Philadelphia, 1949 exhalation, the patient relaxes and allows gravity to lengthen the muscle. (p. 246). A comparable self-stretch for the fibers 11. Evjenth O, Hamberg J: Muscle Stretching in of the posterior gluteus minimus is ob- tained by flexing the thigh approximately Manual Therapy, A Clinical Manual. Alfta 30° and letting it hang over the end of a table or bed, as in Figure 9.6B. Resistance Rehab F0rlag, Alfta, Sweden, 1984 (p. 107). of gravity alone during inhalation pro- 12. Ferner H, Staubesand J: Sobotta Atlas of Human duces the desired gentleness of contrac- tion of the involved muscle. Then, during Anatomy, Ed. 10, Vol. 2. Urban & Schwarzen- exhalation, gravity is a desirable and ef- fective force to encourage gentle release berg, Baltimore, 1983 (Fig. 152). of the tight fibers. 13. Ibid. (Fig. 405). 14. Ibid. (Fig. 4 1 0 ) . Attempts to self-stretch this muscle in 15. Ibid. (Fig. 4 1 8 ) . the standing position are difficult and 16. Ibid. (Fig. 4 2 0 ) . awkward. It is necessary to place the thigh alternately in adduction-flexion and 17. Gainer JV, Chadduck WM, Nugent GR: Causes of adduction-extension. While weight bear- sciatica. Postgrad Med 5 6 : 1 1 1 - 1 1 7 , 1974. ing, the patient must try to relax these postural gluteal muscles and maneuver to 18. Good MG: What is \"fibrositis\"? Rheumatism 5: stretch them. If one attempts this standing self-stretch, it is essential to hold onto 117-123, 1949. something substantial, such as a file cabi- 19. Gould N: Back-pocket sciatica. N Engl J Med 290: net or dresser, for support and balance. 633, 1974. References 20. Greenlaw RK: Function of Muscles About the Hip 1. Anderson JE: Grant's Atlas of Anatomy, Ed. 8. Wil- During Normal Level Walking. Queen's University, liams & Wilkins, Baltimore, 1983 (Figs. 4-33, 4- 34). Kingston, Ontario, 1973 (thesis) (pp. 89-92, 134-135). 21. Gutman H, Zelikovski A, Gadoth N, et al.: Sci- atic pain: A diagnostic pitfall. J Cardiovasc Surg 28:204-205, 1987. 22. Hollinshead WH: Anatomy for Surgeons, Ed. 3., Vol. 3, The Back and Limbs. Harper & Row, New York, 1982 (pp. 664-666). 23. Inman V: Functional aspects of the abductor muscles of the hip. J Bone Joint Surg 2 9 : 6 0 7 - 6 1 9 , 1947. 24. Kellgren JH: Sciatica. Lancet 1:561-564, 1941. 25. Lewinnek GE: Management of low back pain and sciatica. Int Anesthesiol Clin 2 1 : 6 1 - 7 8 , 1983. 26. Lewit K: Chain reactions in disturbed function of the motor system. Manual Med 3 : 2 7 - 2 9 , 1987. 27. Lewit K, Simons DG: Myofascial pain: relief by post-isometric relaxation. Arch Phys Med Rehabil 65:452-456, 1984. 28. Little H: Trochanteric bursitis:a common cause of pelvic girdle pain. Can Med Assoc J 7 2 0 : 4 5 6 - 458, 1979. 29. Lovejoy CO: Evolution of human walking. Scien- tif Am 2 5 9 : 1 1 8 - 1 2 5 , 1988. 30. McMinn RMH, Hutchings RT: Color Atlas of Human Anatomy. Year Book Medical Publishers, Chicago, 1977 (pp. 264, 273, 274). 31. Ibid. (p. 293A). 32. Mitchell FL Jr, Moran PF, Pruzzo NA: An Evalua- tion and Treatment Manual of Osteopathic Muscle Energy Procedures. Mitchell, Moran and Pruzzo,

Chapter 9 / Gluteus Minimus Muscle 185 Associates, Valley Park, MO, 1979 (pp. 425‐435).  and  R.  Melzack,  Ed  2.  Churchill  Livingstone,  London,  33. Negrin P, Fardin P: Clinical and electromy‐ographical  1989 (pp. 368‐385).  48. S0gaard  IB:  Sciatic  nerve  entrapment.  J Neurosurg course  of  sciatica:  prognostic  study  of  41  cases.  58:275‐276, 1983.  Electromyogr Clin Neurophysiol 27: 225‐127, 1987.  49. Spalteholz W: Handatlas der Anatomie des Men-schen, 34. Netter  FH:  The Ciba Collection of Medical Illustrations, Ed. 11, Vol. 2. S. Hirzel, Leipzig, 1922 (p. 359).  Vol.8,  Musculoskeletal  System.  Part  I:  Anatomy,  50. Toldt  C:  An Atlas of Human Anatomy, translated  by  Physiology  and  Metabolic  Disorders.  Ciba‐Geigy  M.E.  Paul,  Ed.  2,  Vol.  1.  Macmillan,  New  York,  1919  Corporation, Summit, NJ, 1987 (p. 85).  (pp. 341, 342).  35. Pernkopf E: Atlas of Topographical and Applied Human 51. Ibid. (p. 353).  Anatomy, Vol.  2.  W.B.  Saunders,  Philadelphia,  1964  52. Travell  J:  Factors  affecting  pain  of  injection.  JAMA (Fig. 316).  758:368‐371, 1955.  36. Ibid. (Fig. 329).  53. Travell J: Symposium on mechanism and management  37. Rasch PJ, Burke RK: Kinesiology and Applied Anatomy, of  pain  syndromes.  Proc Rudolf Virchow Med Soc Ed. 6. Lea & Febiger, Philadelphia, 1978 (p. 276).  76:126‐136, 1957 (p. 133, Fig. 5).  38. Reynolds MD: Myofascial trigger point syndromes in  54. Travell  J,  Rinzler  SH:  The  myofascial  genesis  of  pain.  the  practice  of  rheumatology.  Arch Phys Med Rehabil Postgrad Med 77:425‐434, 1952.  62:111‐114, 1981.  55. Travell  W,  Travell  J:  Technique  for  reduction  and  39. Rubin  D:  An  approach  to  the  management  of  ambulatory  treatment  of  sacroiliac  displacement.  Arch myofascial  trigger  point  syndromes.  Arch Phys Med Phys Ther 23:222‐246, 1942.  Rehabil 62:107‐110, 1981.  56. Travell  J,  Travell  W:  Therapy  of  low  back  pain  by  manipulation  and  of  referred  pain  in  the  lower  40. Schapira D, Nahir M, Scharf Y: Trochanteric bursitis: a  extremity  by  procaine  infiltration.  Arch Phys Med common  clinical  problem.  Arch Phys Med Rehabil 27:537‐547, 1946.  67:815‐817, 1986  57. Voss  H:  Tabelle  der  Muskelgewichte  des  Man‐nes,  berechnet  und  zusammengestellt  nach  den  41. Scott  M:  Lower  extremity  pain  simulating  sciatica:  Untersuchungen  von  W.  Theile  (1884).  Anat Anz tumors of the high thoracic and cervical cord as causes.  703:356‐360, 1956.  JAMA 760:528‐534, 1956.  58. Weber  EF:  Ueber  die  Langenverhaltnisse  der  Fleischfasern  der  Muskeln  in  Allgemeinen.  Ber-ichte 42. Sheon RP, Moskowitz RW, Goldberg VM: Soft Tissue uber die Verhandlungen der Kdniglich Sachsis-chen Rheumatic Pain, Ed.  2.  Lea  &  Febiger,  Philadelphia,  1987 (pp. 165, 168‐169).  Gesellschaft der Wissenschaften zu Leipzig 3: 63‐86,  1851.  43. Simons,  DG:  Myofascial  pain  syndromes,  part  of  59. Werner  A,  Gaitzsch  J:  Hypogastric  artery  aneurysm:  a  Chapter  11.  In  Medical Rehabilitation, edited  by  J.V.  very  rare  cause  of  sciatica  (and  a  tricky  diagnostic  Basmajian  and  R.L.  Kirby.  Williams  &  Wilkins,  problem!) Surg Neurol 70:89‐91, 1978.  Baltimore, 1984 (p. 319).  60. Wilson  GL,  Capen  EK,  Stubbs  NB:  A  fine‐wire  electromyographic  investigation  of  the  gluteus  44. Simons DG: Myofascial pain syndromes due to trigger  minimus  and  gluteus  medius  muscles.  Res Quart points:  2.  Treatment  and  single‐muscle  syndromes.  47:824‐828, 1976.  Manual Med 1:72-77, 1985.  61. Zohn DA: Musculoskeletal Pain: Diagnosis and Physical Treatment, Ed.  2.  Little  Brown  and  Company,  Boston,  45. Simons DG: Myofascial pain syndrome due to trigger  1988 (p. 212).  points,  Chapter  45.  In  Rehabilitation Medicine, edited  by  Joseph  Goodgold.  C.  V.  Mosby  Co.,  St.  Louis,  1988  (pp. 686‐723).  46. Simons DG, Travell JG: Myofascial origins of low back  pain.  3.  Pelvic  and  lower  extremity  muscles.  Postgrad Med 73:99‐108, 1983.  47. Simons  DG,  Travell  JG:  Myofascial  pain  syndromes,  Chapter  25.  In  Textbook of Pain, edited  by  P.D.  Wall   

CHAPTER 10 Piriformis and Other Short Lateral Rotators Gemelli, Quadratus Femoris, Obturator Interims, and Obturator Externus Muscles \"Double Devil\" HIGHLIGHTS: The piriformis muscle is respon- marily lateral rotation of the thigh with the hip ex- sible for the symptoms of the piriformis syn- tended; it also acts in abduction when the hip is drome and is a \"double devil\" because it causes flexed 90°. The remaining five short deep rotator as much distress by nerve entrapment as it does muscles are primarily lateral rotators in either by projecting pain from trigger points (TrPs). RE- position. In weight-bearing activities, the piri- FERRED PAIN from a TrP in the piriformis mus- formis restrains vigorous or excessive medial ro- cle may radiate to the sacroiliac region, laterally tation of the thigh. SYMPTOMS of the piriformis across the buttock and over the hip region pos- syndrome may be caused by referral of pain teriorly, and to the proximal two-thirds of the from TrPs in the muscle, by nerve entrapment posterior thigh. Pain patterns of the other five and/or vascular compromise when neurovascu- short lateral rotators of the hip have not been lar structures are compressed by the muscle distinguished from those of the piriformis mus- against the rim of the greater sciatic foramen, cle. The intrapelvic portion of the obturator in- and by sacroiliac joint dysfunction. The myofas- ternus is considered in Chapter 6. ANATOMI- cial pain component of this syndrome includes CAL ATTACHMENTS of the piriformis muscle pain in the low back, buttock, and posterior thigh medially are primarily to the inner surface of the that usually is increased by sitting, standing, and sacrum. The piriformis exits the pelvis through walking. ACTIVATION of TrPs in the piriformis the greater sciatic foramen. Laterally, its tendon, muscle results from acute overload, as when with those of the other short lateral rotators, at- catching oneself from a fall or when restraining taches to the greater trochanter of the femur. vigorous and/or rapid medial rotation of the Medially, the two gemelli and the quadratus weight-bearing limb (for example, during run- femoris muscles attach to the ischium; the obtu- ning). Sustained overload perpetuates these rator internus attaches to the inner surface of TrPs, as when holding the thigh flexed in abduc- the obturator membrane and to the rim of the tion for prolonged periods while driving a car. obturator foramen. The obturator externus at- PATIENT EXAMINATION reveals a tendency for taches medially to the outer surface of the obtu- the seated patient to squirm and shift position rator membrane and to the rim of the obturator frequently. The Pace Abduction Test is usually foramen. INNERVATION of the piriformis muscle positive. In the supine position, the foot of the is directly from the first and second sacral involved side is laterally rotated, and medial ro- nerves. The obturator externus is supplied by tation of that limb is restricted in range as com- the obturator nerve from spinal nerves L3 and L4. pared with the normal side. In the prone posi- The remaining short lateral rotators receive in- tion, pelvic asymmetry may be noted. Standing nervation through motor nerves that may arise examination may reveal an apparent lower limb- from spinal nerves L4 to S3. FUNCTION of the length inequality and a tilted sacral base. Bone piriformis in the non-weight-bearing limb is pri- scan scintigraphy may image a piriformis mus- 186

Chapter 10 / Piriformis and Other Short Lateral Rotators 187 cle with active TrPs. Additional evidence for en- This is followed by full active abduction and ad- trapment of nerves passing through the greater duction of the thigh and application of moist sciatic foramen supports the diagnosis of a piri- heat. Postisometric relaxation, ischemic com- formis syndrome. The piriformis muscle is ac- pression, massage, and ultrasound, alone or in cessible to TRIGGER POINT EXAMINATION in- combination, also may inactivate these TrPs. directly outside of the pelvis by palpation The INJECTION-AND-STRETCH procedure for through the gluteus maximus muscle and di- piriformis TrPs is accomplished either by a com- rectly inside the pelvis by rectal or vaginal exam- pletely external approach or with guidance from ination. The remaining five short lateral rotators intrapelvic palpation. The lateral TrPs are lo- are all palpable through the gluteus maximus cated for injection by flat palpation through the from outside the pelvis; the obturator internus gluteus maximus muscle. Medial TrPs near the can also be palpated from within the pelvis. EN- greater sciatic foramen are so deep and close to TRAPMENTS are numerous. The nerves and the sciatic nerve that it is best to palpate them blood vessels that pass through the greater sci- directly through the rectum or vagina; the needle atic foramen along with the piriformis are subject is then directed toward the finger that is palpat- to entrapment when the muscle is sufficiently ing the TrP. Injection is followed by passive enlarged to fill the foramen. The vulnerable stretch. CORRECTIVE ACTIONS include cor- structures include the superior and inferior glu- recting the asymmetry produced by a lower teal nerves and blood vessels, the sciatic nerve, limb-length inequality and/or a small hemipelvis, the pudendal nerve and vessels, the posterior and restoring normal movement to a blocked femoral cutaneous nerve, and the nerves sup- sacroiliac joint. Postural stress is reduced by plying the gemelli, obturator internus, and quad- maintaining a comfortable sleep position, using ratus femoris muscles. INTERMITTENT COLD a rocking chair, and by changing seated position WITH STRETCH of the piriformis muscle can regularly and stopping to walk at intervals when best be accomplished with the patient side lying driving a car for prolonged periods. Mechanical and the involved thigh uppermost, flexed to 90° overload of the muscles must be avoided. A at the hip. The muscle is lengthened by ad- self-stretch home program is established. This ducting the flexed thigh as vapocoolant spray or program may include ischemic compression of ice is applied distalward across the buttock over the TrPs, but with great care to avoid nerve the piriformis muscle and the posterior thigh. compression. 1. REFERRED PAIN Other authors have associated the piri- (Fig. 10.1) formis syndrome with pain in the but- Piriformis trigger points (TrPs) frequently tock42,80,95 and down the back of the contribute significantly to complex myo- thigh.43,56,80, 1 0 0 Pain caused by the piri- fascial pain syndromes of the pelvic and formis muscle has been described as hav- hip regions. ing a sciatic radiation109 and as causing The myofascial pain syndrome of lumbago86 or low back pain.109 Some au- the piriformis muscle is well recog- thors localized this pain in the region of nized.43,68,69,71,94,95,109 Additional pain re- the coccyx.56, 100 Pain was also noted in the ferred from TrPs in the adjacent members inguinal area and at the greater trochan- of this lateral rotator group may be diffi- ter.99 cult to distinguish from pain originating Many investigators have attributed the in the piriformis TrPs. pain of the piriformis syndrome to com- The TrPs in the piriformis muscle refer pression by the muscle of the sciatic and pain primarily to the sacroiliac region, to other nerves as they pass through the the buttock generally, and over the hip greater sciatic foramen with the piri- joint posteriorly; the referred pain some- formis.1,20,43,50,64,66,72,80,93,95,99 This nerve-en- times also extends over the proximal two- trapment pain has a different origin than thirds of the posterior thigh (Fig. 10.1). the myofascial pain referred by active The pattern of pain referred by the more TrPs in the piriformis muscle; however, lateral TrP1 and that referred by the more the two often occur together. The neuro- medial TrP2 are similar.87,88,90 genic pain may extend down the entire

188 Part 1 / Lower Torso Pain referred from trigger points (TrPs) (Xs) in the right piri- be felt as less intense pain than that of the essential formis muscle (darker red). The lateral X (TrP1) indi- pattern (solid red). Spillover pain may be absent. cates the most common TrP location. The red stip- posterior thigh and the calf, and to the second, third, and fourth anterior sacral sole of the foot. foramina (Fig. 10.2A). Some fibers may at- tach to the margin of the sciatic foramen 2. ANATOMICAL ATTACHMENTS AND at the capsule of the sacroiliac joint40,41,68 CONSIDERATIONS and some fibers to the sacrospinous liga- (Figs. 10.2 and 10.3) ment.19,40 Laterally, the muscle is secured by a rounded tendon onto the greater tro- Muscles chanter on the medial side of its superior surface (Figs. 10.2B and 10.6). This ten- The piriformis is a thick and bulky mus- don often blends with the common ten- cle in most individuals; it is occasionally don of the obturator internus and gemelli thin and is rarely absent.10,108 The piri- muscles.19 formis muscle can be small with only one or two sacral attachments. Conversely, it Variations of the piriformis muscle in- can be so broad that it joins with the cap- clude additional medial attachments to sule of the sacroiliac joint above and also the first and fifth sacral vertebrae and to with the anterior surface of the sacro- the coccyx. It may fuse with the gluteus tuberous19,40 and/or sacrospinous40 liga- medius or minimus above, or with the su- ments below.19 perior gemellus below. In fewer than 20% of bodies it is divided into two distinct The name of the piriformis is derived portions through which part or all of the from the Latin pirum (pear) and forma sciatic nerve passes (see Section 1 0 ) . 1 0 , 6 6 (shape); it was coined by Adrian Spige- lius, a late 16th and early 17th century The piriformis muscle exits the inside Belgian anatomist.30 This muscle is of the pelvis through the greater sciatic fo- anchored medially to the anterior (inter- ramen. This rigid opening is formed ante- nal) surface of the sacrum usually by riorly and superiorly by the posterior part three fleshy digitations between the first, of the ilium, posteriorly by the sacro-

Chapter 10 / Piriformis and Other Short Lateral Rotators 189 Figure 10.2. Attachments of the right piriformis muscle (red). A, seen from in- side the pelvis in midsagittal view show- ing the attachment of the muscle on the inside of the sacrum, usually between the first four anterior sacral foramina. The fourth foramen is not shown. S, seen from behind (posterior view). In this figure, a relatively small muscle exits the pelvis through a relatively large sciatic foramen. Its rounded tendon attaches laterally to the superior surface of the greater trochanter. The muscle traverses the greater sciatic foramen just above the sacrospinous ligament. Most of the muscle is accessible to external palpa- tion and nearly half of the muscle belly is accessible to palpation inside the pelvis. Sacrospinous ligament Greater sciatic foramen Sacrospinous Obturator ligament foramen tuberous ligament, and interiorly by the distal to the piriformis muscle. Like it, sacrospinous ligament.20 When the mus- they are deep to the gluteus maximus cle is large and fills this space, it has the muscle, but in contrast to the usual posi- potential of compressing the numerous tion of the piriformis, they pass anterior vessels and nerves that exit the pelvis to the sciatic nerve (Fig. 10.3). To locate with it. these muscles in patients, it is helpful to note that deep to the gluteus maximus, The other short lateral rotators of the the piriformis and the upper three thigh at the hip, the four \"GOGO\" mus- \"GOGO\" muscles form a fanlike arrange- cles (superior gemellus, obturator in- ment spreading out from the upper end of ternus, inferior gemellus, and obturator the greater trochanter. externus) and the quadratus femoris, lie

190 Part 1 / Lower Torso Pain Gluteus maximus (cut) Gluteus medius (cut) Gluteus minimus Greater Piriformis sciatic foramen Superior gemellus Lesser sciatic Obturator foramen internus Inferior Obturator internus gemellus Ischial tuberosity Sciatic nerve Obturator externus Quadratus femoris Figure 10.3. Piriformis muscle, regional anatomy: cles have been cut and removed; the distal cut ends of these gluteal muscles are not shown since they would Posterior view of anatomical relations of the right piri- obscure the attachment of the piriformis to the femur. formis muscle (dark red) to neighboring muscles (light red). The gluteus maximus and gluteus medius mus- The superior and inferior gemelli mus- the femur and attaches on the greater tro- cles attach medially to the ischium and chanter near but distal to the piriformis laterally to the medial surface of the up- tendon. per part of the greater trochanter, proxi- mal to and nearly parallel with the quad- The subtendinous bursa of the obtura- ratus femoris muscle (Fig. 10.3). tor internus muscle lies between its ten- don and the capsule of the hip joint and Between the two gemelli lies the obtu- may communicate with the ischiadic rator internus, which is partly an in- bursa between the obturator internus trapelvic muscle and partly a hip muscle muscle and the ischium. (Fig. 10.3). Medially, it is attached to and covers the inner surface of the obturator The quadratus femoris is a rectangu- membrane and attaches to the rim of the lar muscle with parallel fibers that at- obturator foramen, except where the obtu- tach medially to the anterolateral sur- rator nerve and vessels leave the pelvis face of the ischium, caudad to the infe- through the lateral part of the membrane. rior gemellus and posterior to the obturator externus. Laterally, it attaches The obturator internus muscle exits the to the femur on the quadrate tubercle pelvis through the lesser sciatic foramen. and along the intertrochanteric crest, Laterally, the fiber bands of the obturator which extends longitudinally about half- internus converge onto a tendon that is way between the greater and lesser tro- usually shared with the gemelli muscles. chanters (Fig. 10.3).22,46 This tendon inserts on the anterior part of the medial surface of the greater trochan- The obturator externus muscle is con- ter proximal to the trochanteric fossa of sidered part of the adductor group by Hol- linshead;46 however, he notes that its pri-

Chapter 10 / Piriformis and Other Short Lateral Rotators 191 mary action would be lateral rotation and Collectively, these nerves are responsi- not adduction of the thigh. Laterally, the ble for all gluteal muscle sensation and obturator externus attaches to the femur function, anterior perineal sensory and at the trochanteric fossa deep to the quad- motor function, and nearly all of the sen- ratus femoris; it passes across the distal sation and motor function in the posterior part of the capsule of the hip joint to thigh and calf. It is apparent that chronic anchor medially to the external surface of compression of these nerves would cause the obturator membrane. From the poste- buttock, inguinal, and posterior thigh rior view it is nearly covered by the quad- pain, as well as pain lower in the limb. ratus f e m o r i s 3 4 , 3 6 , 8 2 (Fig. 10.3). A bursa of- ten intervenes where the obturator ex- Supplemental References ternus crosses the lesser trochanter. Atlases of anatomy show the attachment of the Nerves in the Greater Sciatic Foramen piriformis muscle to the most proximal surface of the greater trochanter,7,37,60 to the sacrum,38,57 and Of critical importance to understand- to the ilium.37,59 The muscle is presented in cross ing piriformis entrapment syndromes is section18 and as seen from above inside the pel- knowledge of the distribution of the neu- vis.2 rovascular structures that exit the pelvis with the muscle through the unyielding The side view from within the pelvis3,21,35,58,103 greater sciatic foramen. The superior glu- portrays the structures palpated on internal exam- teal nerve and blood vessels usually pass ination. One view shows how the sacral roots of between the superior border of the piri- the sciatic nerve lie between the piriformis mus- formis and the upper (sacroiliac) rim of cle and the examining finger.4 The posterior view the foramen. This nerve supplies the glu- shows special relations for the piriformis, the teus medius, gluteus minimus, and tensor \"GOGO\" muscles, and the quadratus femoris, and fasciae latae muscles.25 The sciatic nerve is useful when palpating tender areas in the lower usually exits between the piriformis mus- lateral buttock.5,82,102 Similar views that include cle and the rim of the greater sciatic fora- the sciatic nerve serve to orient needle insertion men (Fig. 10.3). It supplies the skin and into these muscles in relation to the greater tro- muscles of the posterior thigh and most of chanter and the sciatic nerve.6,34,61,73,83 the leg and foot. Also exiting the pelvis along the lower border of the piriformis Authors73,102 have illustrated the large bursa that are the pudendal nerve and vessels. The cushions the obturator internus as it turns sharply pudendal nerve then crosses the spine of around the smooth bone of the lesser sciatic the ischium and reenters the pelvis notch. The location of the obturator externus can through the lesser sciatic foramen, which be seen with the overlying quadratus femoris re- is identified in Figure 10.3. It supplies the moved.36 external anal sphincter muscle and helps supply the skin of the posterior thigh and 3. INNERVATION scrotum or labia majora. This nerve also innervates the bulbocavernosus, ischio- The piriformis muscle is usually supplied cavernosus, and sphincter urethrae mem- by both the first and second sacral nerves branacea muscles; the skin and corpus as they emerge from the anterior sacral fo- cavernosus of the penis in the male; and ramina, but sometimes it is supplied by the corresponding structures of the clito- only one nerve, either S1 or S .2 19 ris in the female.26 Innervation of these structures is essential to normal sexual One nerve carrying fibers from L5-S2 or function. The inferior gluteal nerve, S1-S3 supplies the obturator internus and which exclusively supplies the gluteus the superior gemellus.46 The nerve to the maximus muscle,25 the posterior femoral quadratus femoris sends a twig to the in- cutaneous nerve, and the nerves to the ferior gemellus and contains fibers from gemelli, obturator internus, and quad- L 4 , L 5 , and S .1 1 9 Unlike all the other short ratus femoris muscles also pass through lateral rotators, the obturator externus re- the greater sciatic foramen with the piri- ceives its innervation from a branch of the formis muscle. obturator nerve. This branch comes either from the obturator nerve before it divides into anterior and posterior branches or from the posterior branch. The posterior branch pierces the muscle.23

192 Part 1 / Lower Torso Pain All of these nerves (except the innerva- the frontal plane and lies at an angle of tion to the piriformis muscle itself and approximately 30° to the plane of the ad- the nerve to the obturator externus) are jacent sacroiliac (SI) joint. As illustrated vulnerable to compression as they pass by Retzlaff and associates,80 the lower fi- through the greater sciatic foramen to- bers of the piriformis muscle are able to gether with the piriformis muscle. produce a strong rotary shearing force on the SI joint. This force would tend to dis- 4. FUNCTION place the ipsilateral base of the sacrum anteriorly (forward) and the apex of the In weight-bearing activities, the piri- the sacrum posteriorly.80 formis is often needed to restrain (control) vigorous and/or rapid medial rotation of 5. FUNCTIONAL (MYOTATIC) UNIT the thigh, for example, during the early stance phase of walking and running. The The piriformis and the other five short piriformis muscle is also thought to stabi- lateral rotator muscles, together with the lize the hip joint and to assist in holding gluteus maximus, are the prime lateral ro- the femoral head in the acetabulum.19 tators of the thigh.45,77 They are assisted by the long head of the biceps femoris, The six \"short lateral rotators\" com- the sartorius, posterior fibers of the glu- prise the piriformis, the superior and in- teus medius, sometimes by the posterior ferior gemelli, the obturator internus and fibers of the gluteus minimus, and by the externus, and the quadratus femoris. The iliopsoas, the last particularly in infants.45 piriformis is primarily a lateral rotator with the hip neutral or extended. It also The antagonists that produce medial ro- abducts the thigh when the hip is flexed tation of the thigh combine other func- 90°. The remaining five short lateral rota- tions and are relatively weak rotators, tor muscles are almost exclusively lateral namely, the semitendinosus and semi- rotators77 in either flexion or extension. membranosus, tensor fasciae latae, pec- tineus, and the most anterior fibers of the Examination of an articulated skeleton gluteus medius and gluteus minimus makes it apparent that the degree of flex- muscles.45,77 The role of the adductors in ion of the thigh profoundly affects the this regard has been considered contro- function of the piriformis muscle. At 90° versial;45 however, EMG studies have of flexion it produces horizontal abduc- shown that the adductores longus and tion of the thigh.19, 4 6 , 7 6 However, with full magnus are activated during medial rota- flexion at the hip, it appears to rotate the tion but not during lateral rotation of the thigh medially. The action of the other thigh at the hip.12 short lateral rotators is less influenced by flexion of the thigh at the hip. The degree 6. SYMPTOMS of hip flexion is an important factor when considering the optimal stretch position. Piriformis Syndrome No electromyographic (EMG) study of Retzlaff noted, \"The piriformis muscle the functional kinesiology of any of these syndrome frequently is characterized by muscles was found. The actions of the such bizarre symptoms that they may piriformis, gemelli, and quadratus fe- seem unrelated\".80 Pain (and paresthe- moris muscles were studied by Duchenne sias) may be reported in the low back, using electrical stimulation.29 Stimulation groin, perineum, buttock, hip, posterior of the piriformis with the thigh neutral thigh and leg, foot, and, during defeca- produced lateral rotation of the thigh tion, in the rectum. Symptoms are aggra- with some extension and slight abduc- vated by sitting, by a prolonged combina- tion. Stimulation of the superior gemel- tion of hip flexion, adduction, and medial lus, obturator internus, and inferior rotation, or by activity. In addition, the gemellus as a group caused pure lateral patient may complain of swelling in the rotation of the thigh, as did stimulation of painful limb and of sexual dysfunction, the quadratus femoris. dyspareunia in females, and impotence in males. Mitchell63 noted that the piriformis ex- erts an oblique force on the sacrum. The plane of the muscle closely approximates

Chapter 10 / Piriformis and Other Short Lateral Rotators 193 Prevalence atomical relations and, in 1937,41 first de- scribed surgical release of the piriformis The patients seen on a Back Service who to relieve the syndrome. In 1941,42 he was suffered from piriformis syndrome were still perplexed as to what caused the mus- greater in number than the patients with cle to be too large for the foramen. Some nerve root deficit caused by disc protru- authors14,85,89,94 1 0 6 have assumed that ana- sion. The ratio of female to male patients tomical variations in the position of the with piriformis syndrome was 6:1.71 sciatic nerve relative to the piriformis Kipervas and co-workers50 considered muscle predispose that nerve to compres- spasm of the piriformis muscle to be one sion by the muscle. of the most frequent myotonic reflexes in lumbar osteochondrosis (used by these au- When actively contracting and shorten- thors to mean musculoskeletal low back ing, any muscle markedly increases its pain). The gynecologist, Shordania,86 re- girth and becomes tense. (A shortening ported that 8.3% of 450 women attending muscle fiber must increase in diameter as a polyclinic for lumbago had a hard, its actin and myosin filaments increas- swollen, extremely tender piriformis ingly overlap each other side by side.) muscle, which he considered responsible Therefore, when the piriformis muscle at for their pain. This syndrome is not a rest snugly fills the limited space avail- common cause, but it is a significant and able in the greater sciatic foramen, the ac- treatable cause of otherwise enigmatic companying nerves and vessels must be pain. compressed whenever the muscle is shortened or contracted. Popelianskii and Bobrovnikova75 found a piriformis syndrome in 105 (43.7%) of A relatively small muscle in a large 240 patients with signs and symptoms of greater sciatic foramen could develop lumbosacral radiculitis. Patients with evi- pure myofascial pain without an entrap- dence of S1 nerve root compression re- ment component. Conversely, a relatively sponded to piriformis muscle therapy large muscle that fills the foramen and much better than did patients with evi- then shortens because of active TrPs dence of L5 root compression. would be expected to produce entrap- ment symptoms in addition to myofascial Three Components referred pain. It now appears that three specific condi- In the past, inflammation of the piri- tions may contribute to the piriformis formis has been thought to be the cause of syndrome: (a) myofascial pain referred the syndrome. Freiberg,42 however, in his from TrPs in the piriformis muscle; (b) summary of 12 operations on the piri- nerve and vascular entrapment by the pir- formis, noted that in no instance was iformis muscle at the greater sciatic fora- excised piriformis tissue reported as dis- men, and (c) dysfunction of the SI joint. eased. This substantiates Pace's conten- tion that applying the term \"piriform- The original, now classic, descriptions itis\"86 to this condition is a confusing misnomer, with which we agree. by Pace69 and by Pace and Nagle71 of the piriformis syndrome as a myofascial pain syndrome due to TrPs have been rein- Dysfunction of the SI joint has been forced or confirmed by subsequent au- considered a common and important thors.11,43,68,75,92,94,95,109 The taut bands and component of the piriformis syn- shortened muscle fibers associated with drome.44,51,80,95,106 Displacement of the SI TrPs represent one mechanism that joint may interact with myofascial TrPs of would, in effect, place the muscle in sus- the piriformis muscle to establish a self- tained tension with bulging of its diame- sustaining relation. The sustained tension ter. Historically, many authors have recog- of the muscle caused by the TrPs could nized the potential for entrapment of the maintain displacement of the joint,51 and nerves and vessels passing through the the dysfunction induced by the joint dis- greater sciatic foramen by the piriformis placement apparently perpetuates piri- muscle.1.11.40,41,43,56,64,68,75,78,93,94 Freiberg, in formis TrPs. In this situation, both condi- 1934,40 clearly described these critical an- tions must be corrected.

194 Part 1 / Lower Torso Pain Origin of Symptoms ful.68,71 Pudendal nerve entrapment may cause impotence in men.80 A patient of ei- The three components of the piriformis ther sex may experience inguinal (groin) pain.1,71 syndrome, myofascial TrPs, neurovascu- Pain immediately posterior to the lar entrapments, and articular dysfunc- greater trochanter can be the result of en- trapment of the nerves to the gemelli, ob- tion, are responsible for different but of- turator internus, and quadratus femoris muscles. The presence of local tenderness ten overlapping symptoms. should lead one to look for TrPs in these muscles. Pain directly attributable to myofascial Differential Diagnosis TrPs in the piriformis muscle includes low The piriformis myofascial pain syndrome back pain,64,69,71,80 buttock pain,1,11,43,71,75 hip is recognized by the characteristic pain pattern projected by its TrPs, by pain and pain,80 and posterior thigh pain.43,69,71,80 weakness on resisted abduction of the thigh with the hip flexed 90°, by eliciting This same myofascial cause is implicated tenderness of the piriformis muscle using external palpation, and by palpating taut when pain is increased by sitting,43,80,94 by bands and tenderness via intrapelvic ex- amination. The piriformis syndrome may arising from the sitting position,43 or be the cause of a \"postlaminectomy syn- drome\" or of coccygodynia.79 while standing.80 Pressure of a hard bolus Nerve entrapment is suggested by par- of feces against TrPs in a patient's left pir- esthesias and dysesthesias in the distribu- tion of nerves passing through the greater iformis muscle caused \"rectal\" pain dur- sciatic foramen and by sensory disturb- ance extending well beyond midthigh. ing defecation when the patient was con- Malignant neoplasm, neurogenic tumors, and local infection can compress the sci- stipated.68 Pain is typically aggravated by atic nerve at the greater sciatic foramen. These conditions have been identified by sitting, by prolonged hip flexion, adduc- CT scanning.27 Sacroiliac joint displace- ment is likely to coexist with a piriformis tion, and medial rotation, and by activ- myofascial syndrome,44,51,99, 1 0 6 and is rec- ognized by the physical signs of pelvic ity.11 Recumbency may not provide relief torsion noted in Section 8 of this chapter. from a myofascial piriformis syndrome80 Another source of pain referred to the buttock and lateral thigh is an episacro- if the TrPs are more than moderately irri- iliac lipoma.70 These herniated nodules of fat are exquisitely tender to palpation and table. are responsive to injection of a local anes- thetic. Sometimes they require surgical Compression of the superior and infe- removal under local anesthesia for lasting relief. rior gluteal nerves and vessels could con- Symptoms of the piriformis syndrome tribute to the nearly universal complaint are easily confused with those of a her- niated intervertebral disc. Absence or of buttock pain.1,43,71,78,93,94 More severe marked weakness of the Achilles tendon reflex,42 and motor denervation shown by compromise of these nerves would ex- electromyography, suggest a disc lesion. Conversely, slowing of conduction veloc- plain gluteal muscle atrophy.78 ity in the sciatic nerve through the pelvis suggests piriformis entrapment. Palpation Pain in the region of the SI joint may be due to dysfunction of that j o i n t . 6 8 , 8 0 , 9 9 , 1 0 5 , 1 0 6 Pressure on the sciatic nerve or on the posterior femoral cutaneous nerve in the greater sciatic foramen is a likely additional source of posterior thigh pain.1,43,56,64,69,71,80,93,94 Sciatic nerve entrap- ment can be responsible for the pain and paresthesias projecting to the leg (calf] and often to the foot.1,11,40,43,64,80,93,94 Numb- ness of the foot43,64 and loss of position sense producing a broad-based, ataxic gait have also been noted.94 Pain on prolonged slouched sit- ting,1,43,80 particularly on a hard surface,94 may be due to pressure on piriformis TrPs or to additional pressure on the sciatic nerve at its point of entrapment, or to both. Piriformis entrapment of the pudendal nerve may evoke perineal pain and sexual dysfunction. Female patients are likely to complain of painful intercourse (dys- pareunia).71,80, 93 Simply spreading the thighs apart may be distressingly pain-

Chapter 10 / Piriformis and Other Short Lateral Rotators 195 for piriformis muscle tenderness is essen- around the swimming pool, but I caught tial to confirm or rule out entrapment and myself and didn't fall.\"71 Other move- should be performed in all cases of \"sciat- ments producing overload are twisting ica.\" Recognition of the piriformis syn- sideways while bending and lifting a drome may avoid needless laminectomy. heavy weight,68 or forceful rotation with the body weight on one leg.71,80 The sec- Incidental radiographic reports of \"nar- ond author treated one young man who rowing of the disc space\" or \"degenera- activated TrPs in this muscle by turning tive changes with spur formation\" are not his body repeatedly to lift and throw by themselves sufficient to account for pieces of firewood behind him. the pain characteristic of the piriformis syndrome. Degenerative changes occur in The piriformis can become overloaded the spine with aging and do not correlate when it undergoes a strong lengthening well with symptoms.96 contraction to restrain vigorous and/or rapid medial rotation of the weight-bear- Symptoms of a facet syndrome with ing limb; this occurs at times during run- low back pain and sciatica (see Chapter 3, ning. Fig. 3.2) may be difficult to distinguish from a myofascial piriformis syndrome Repetitive strain can activate piriformis until the muscle is examined.11 A facet TrPs. One woman, a masseuse at a spa, re- block may relieve the back pain of a facet peatedly used her piriformis to block the syndrome, but only successful inactiva- movement of her body after throwing her tion of the piriformis muscle TrPs re- weight to one side over the client.71 lieves the limp and the buttock and poste- rior thigh pain of myofascial and related Placing a muscle with a latent TrP in entrapment origin.71 the shortened position for a prolonged pe- riod of time is likely to activate the TrP. When the pain and pelvic wall tender- Flexing the thighs at the hips with the ness are bilateral, spinal stenosis should knees spread apart for obstetrical or uro- be considered.71 logical procedures, or for coitus, does just this to the piriformis muscle; this posi- Piriformis syndrome may develop sec- tion has been associated with onset of the ondary to sacroiliitis (sacroiliac arthritis). piriformis syndrome.68,80 The diagnosis of sacroiliitis is confirmed by radiography.68 Sacroiliitis affects one Direct trauma by striking the buttock or both SI joints and may cause pain and over the piriformis muscle with a hard tenderness in the low back, buttock, and object may be responsible for activating lateral thigh that may also extend as far as piriformis TrPs.15,68,80 The unaccustomed the ankle on one or both sides. Patients muscle strain of an accidental overcorrec- with sacroiliitis are usually young people tion of a lower limb-length inequality can who are HLA-B27 positive and may have activate latent piriformis TrPs. ankylosing spondylitis32 (usually bilater- ally symmetrical sacroiliitis81), psoriatic Baker9 examined 34 muscles, including arthritis or Reiter's disease (usually asym- the piriformis, in 100 patients who had metrical sacroiliitis81), or arthritis related experienced a first-time motor vehicle ac- to inflammatory bowel disease.74,81 cident. The piriformis muscle evidenced myofascial TrPs in one-third to one-half 7. ACTIVATION AND PERPETUATION of the patients. Among both drivers and OF TRIGGER POINTS passengers, impact on the driver's side produced the largest percentage of piri- Activation formis involvement; impact from behind produced the lowest percentage. Any unaccustomed overload can activate myofascial TrPs in a related muscle. One Piriformis TrPs are likely to be acti- man overloaded the piriformis while vated by the same stresses that activate spreading his knees maximally and low- TrPs in the posterior divisions of the glu- ering one end of a large container be- teus minimus and gluteus medius mus- tween his knees and onto the floor.71 cles. TrPs in the piriformis seem unlikely Catching oneself in a fall can overload to develop as satellites of TrPs in other many muscles, including the piriformis. muscles. One might hear, \"My foot slipped as I ran

196 Part 1 / Lower Torso Pain Perpetuation shift position. They are likely to have difficulty crossing the involved thigh Immobilization of an involved muscle over the other knee when asked to do so. tends to perpetuate its TrPs. Driving a car Resisted isometric contraction of the with the foot in place on the accelerator muscle is tested as described (and illus- for long periods or sitting on one foot80 trated) by P a c e 6 9 and by Pace anc are activities that can perpetuate piri- Nagel:71 \". . . the examiner places his formis TrPs. hands on the lateral aspects of the knees and asks the patient to push the hands Chronic infections are known to perpet- apart. Faltering, pain, and weakness will uate TrPs. Specifically, chronic pelvic be observed on the affected side.\"71 This inflammatory disease86 and infectious Pace Abduction Test has subsequently sacroiliitis68 have been identified in the been highly regarded.11, 16, 79, 1 0 9 piriformis syndrome. Other conditions that may perpetuate piriformis TrPs in- Patient Supine clude arthritis of the hip joint and condi- tions requiring total hip replacement.71 With the patient resting in the supine po- sition, one is likely to see persistent lat- The Morton foot structure (mediolateral eral rotation of the thigh on the affected rocking foot) tends to increase medial ro- side that is evidenced by an outward rota- tation and adduction of the thigh during tion of the foot of at least 45°. This test walking. The piriformis assists in com- was illustrated by Retzlaff and associ- pensating for this excessive medial rota- ates80 and also described by other au- tion and thereby is overworked, leading thors.76,99 This position indicates shorten- to perpetuation of existing TrPs. Hyper- ing of the piriformis or other lateral rota- pronation of the foot from other causes tors, unless due to the pelvic asymmetry and also lower limb-length inequality can of a hemipelvis that is small in the antero- perpetuate piriformis TrPs. posterior direction, as described in Chap- ter 4. 8. PATIENT EXAMINATION Painfulness and limitation of passive When more than an uncomplicated myo- medial rotation of the affected thigh with fascial piriformis syndrome is suspected, the hip straight in the supine patient was a careful neurological examination of the first described by Freiberg;41 this test was lower limbs is valuable. Additional obser- illustrated by TePoorten,99 and is fre- vations and tests are presented here, ar- quently mentioned,33, 71, 7 6 , 9 9 , 1 0 0 , 1 0 9 often as ranged by patient position during exami- Freiberg's Sign. This movement increases nation. the tension on an already tight piriformis muscle. Patient Upright Popelianskii and Bobrovnikova75 found The patient with entrapment of primarily that pain in a sciatic distribution in re- the peroneal portion of the sciatic nerve sponse to the combination of medial rota- may evidence only mild foot drop with tion and adduction (Bonnet's sign) was weakness of dorsiflexion at the ankle. characteristic of piriformis syndrome. With more extensive entrapment of the sciatic nerve, the patient may limp by Evjenth and Hamberg33 illustrate and dragging the leg on the affected side.71 Pa- describe a variation of the medial rotation tients with severe piriformis syndrome test with the patient supine; the thigh of may be unable to ambulate.49,51 the side to be tested is flexed to 60° at the hip. Tightness of the posterior fibers of While standing, the patient can be ex- the gluteus medius and gluteus minimus amined for SI joint mobility on each side muscles would limit medial rotation by the technique described and illus- more in this flexed position than when trated by Kirkaldy-Willis.51 The painful the hip is straight. limb may be measurably larger in girth. Patients with the piriformis syndrome Patient Seated have a variable degree of restriction of straight-leg raising that is probably more When seated, patients with a piriformis dependent on compression of nerves in syndrome tend to squirm and frequently

Chapter 10 / Piriformis and Other Short Lateral Rotators 197 the greater sciatic foramen than on myo- is more anterior (depressed) in relation to fascial TrP tension of the muscle. the adjacent posterior superior iliac spine. The sacral sulcus is deepened, as Examination of the supine patient at illustrated by Retzlaff and associates.80 times reveals apparent shortening of the They found that the apex (distal tip) of limb on the involved s i d e 8 0 \" that can re- the sacrum is displaced to the left of the sult from distortion of the pelvic axis midline and that the sulcus on the left ap- caused by increased tension of the piri- pears more shallow.80 This torsion of the formis. Conversely, the piriformis syn- pelvis is likely to be associated with drome may be aggravated by a lower malalignment at the symphysis pubis. limb-length inequality that overloads the piriformis muscle. Examination for this Other Tests lower limb asymmetry is described fully in Chapter 4. We agree with those who consider exami- nation of the patient for lower limb- Patient Side Lying length inequality to be important in the piriformis syndrome.11,43 However, clin- With the patient lying on the uninvolved ical assessment for inequality in the su- side, palpation of the uppermost buttock pine or standing patient is subject to mul- consistently reveals exquisite tenderness tiple errors. Standing radiograms to iden- over and just lateral to the greater sciatic tify causes for asymmetry of the lumbar foramen18,75,109 and often along the entire spine, including lower limb-length ine- length of the piriformis. From this exter- quality, can be helpful when carefully nal approach, all of the muscle must be taken and interpreted. Methods of mea- palpated through the gluteus maximus surement and interpretation are described muscle.11,80,99 in Chapter 4. Popelianskii and Bobrovnikova,75 in The myofascial piriformis syndrome is their study of 105 patients with piriformis often associated with entrapment of the syndrome, found that tenderness over the sciatic nerve, with signs and symptoms of area where the sciatic nerve exits from be- L5 and S1 nerve root involvement. Elec- neath the piriformis muscle was often at- trodiagnostic tests for denervation and ex- tributable to either or both the sciatic amination of the nerve roots by computed nerve and the piriformis muscle. They tomography (CT) scan and magnetic reso- saw a number of patients without back- nance imaging (MRI) help confirm or ex- ache whose buttock pain and tenderness clude compression at the nerve root level. at this site was associated with no nerve They also may help detect nerve entrap- tenderness at the crease of the buttock but ment in the greater sciatic foramen. who did have a tense piriformis muscle. Fishman38 examined 24 patients with piriformis A test for tightness of the piriformis syndrome for H (Hoffman) reflex changes when that is more specific than that of Freiberg, the affected lower limb was moved from a neutral because it is influenced less by the other position to 90° of hip flexion with 30-45° of ad- lateral rotators of the hip, was described duction and medial rotation. In this stretch posi- and illustrated by Saudek.84 She placed tion for the piriformis muscle, the sum of the H the patient side lying with the side to be reflex and M wave latencies increased between tested uppermost, stabilized the pelvis 2.5 and 13 millisec without change in the values with one hand, flexed the uppermost of the opposite lower limb in 15 of 24 (63%) of his thigh to 90°, and tested for painful limita- patients. His results support the view that nerve tion of passive adduction of the thigh at entrapment contributes significantly to the symp- the hip. toms in a high percentage of patients with the pir- iformis syndrome and that the electrodiagnostic Patient Prone response to stress positioning can be helpful in confirming the diagnosis. Tightness of the piriformis may subject the sacrum to abnormal rotary stress that A nuclear bone scan using Tc-99m methylene exacerbates pelvic dysfunction.76 Specifi- diphosphonate imaged the muscle in an acute pir- cally, shortening of the right piriformis iformis myofascial syndrome.49 The patient had muscle produces left oblique axis rotation of the sacrum. The sacral base on the right

198 Part 1 / Lower Torso Pain Figure 10.4. External palpation to elicit trigger-point tenderness in the right piri- formis muscle through a relaxed gluteus maximus muscle. The solid line (piri- formis line) overlies the superior border of the piriformis muscle and extends from immediately above the greater tro- chanter to the cephalic border of the greater sciatic foramen at the sacrum. (The technique for locating the piriformis line is illustrated in Figure 8.5B) The line is divided into equal thirds. The dotted line marks the palpable edge along the lateral border of the sacrum, which cor- responds closely to the medial margin of the greater sciatic foramen. The fully rendered thumb presses on the point of maximum trigger-point tenderness at TrP1 which is usually found just lateral to the junction of the middle and lateral thirds of the line. The outlined thumb presses on the location of TrP2 tender- ness at the medial end of the line. presented with a 3-day history of left buttock and through the gluteus maximus muscle. Us- ing this approach, tenderness is less thigh pain so severe that walking was impossible. likely to be palpable in the underlying ob- turator externus. Obturator externus ten- The pain began immediately following a particu- derness is best located by palpating be- tween and deep to the pectineus and ad- larly strenuous tennis serve. Neurological exami- ductor brevis muscles in the groin, thereby exerting pressure on the muscle nation was normal. When the scintigram sug- against the external surface of the obtura- tor membrane. gested the diagnosis of piriformis muscle syn- Piriformis Muscle drome, \"further physical evaluation revealed a The location of the piriformis muscle is TrP in the left piriformis muscle that reproduced determined for external examination by drawing a line (see piriformis line, Fig. the pain exactly. This TrP was injected . . . with 8.56) from the uppermost border of the greater trochanter through the sacroiliac immediate and permanent relief. The CT scan and (cephalad) end of the greater sciatic fora- men (Figs. 10.4 and 8.5B). When the glu- myelogram were canceled.\"49 teus maximus muscle is relaxed, the greater trochanter may be located by cir- 9. TRIGGER POINT EXAMINATION cular deep palpation with the flat of the (Figs. 10.4 and 10.5) hand over the hip laterally, revealing the underlying bony prominence. The cres- Examination of this group of lateral rota- cent-shaped medial boundary of the sci- tor muscles for TrPs is complicated by the atic foramen along the lateral border of fact that all of them lie deep to the gluteus the sacrum (dotted line, Fig. 10.4) is palpa- maximus muscle, as seen in Figure 10.3. ble inferior to the posterior inferior iliac The piriformis muscle can be examined spine through the relaxed gluteus max- through the gluteus maximus for most of imus muscle. its length. Its medial end is accessible to nearly direct palpation by rectal or vagi- nal examination. The femoral (lateral) ends of the gemelli and obturator internus muscles are not individually distinguish- able by external palpation, but much of the intrapelvic obturator internus is di- rectly palpable from inside the pelvis, as discussed and illustrated in Chapter 6. Tenderness in the femoral end of the quadratus femoris may be palpable

Chapter 10 / Piriformis and Other Short Lateral Rotators 199 The structure palpated along this border is the ligament21 is felt as a firm band stretching between the sacrum and the ischial spine long posterior sacroiliac ligament. Its fibers ex- and is normally covered by fibers of the coccygeus muscle109 that also can harbor tend from the ilium to the sacrum close to the SI TrPs. The piriformis muscle lies just cephalad to this ligament and, if in- joint and descend to become continuous with the volved, is tender and feels tense.50,62,71,95,100 The patient is likely to exclaim that, for sacrotuberous ligament.20 The palpable border of the first time, someone has found \"my pain.\"71 this ligament along the sacrum corresponds One can often examine the muscle bi- closely to the medial border of the greater sciatic manually, with one hand pressing exter- nally on the buttock while the other hand foramen. palpates internally. The greater sciatic fo- ramen presents an unmistakable soft spot The outline of a tense piriformis muscle through which palpation pressure from is sometimes palpable along the piriformis one finger outside the pelvis can be trans- line, and the muscle may show marked ten- mitted to another finger inside the pelvis. derness throughout its length.80\" Figure To confirm identification of the piri- 10.3 illustrates how closely the lower bor- formis muscle, the examiner palpates for ders of the gluteus medius and gluteus contractile tension in the muscle while minimus muscles approximate the upper having the patient attempt to abduct the border of the piriformis, permitting palpa- thigh by trying to lift the uppermost knee. tion of the piriformis without interference from them. If one palpates too far cepha- The sacral nerve roots lie between the lad, the gluteus medius and gluteus mini- examiner's finger and the piriformis mus- mus, not the piriformis, are being pal- cle (Fig. 10.5). If the nerve roots are irri- pated deep to the gluteus maximus. tated by entrapment at the greater sciatic foramen, they, too, may be tender and are The lateral TrP1 region of the piriformis likely to project pain in a sciatic distribu- is usually located just lateral to the junc- tion. tion of the middle and lateral thirds of the piriformis line (Fig. 10.4). This lateral TrP Kipervas and co-workers50 reported EMG find- is accessible only by external palpation. The medial TrP2 region is markedly ten- ings in 23 patients with a piriformis muscle injury der when pressure is applied medially over the region of the greater sciatic fora- syndrome associated with lumbar osteochon- men, illustrated by the outlined thumb in Figure 10.4, and as noted also by drosis. The number of patients who had symp- others.56,71,109 These medial TrPs are ex- quisitely tender when examined from toms of radiculopathy in addition to myofascial within the pelvis. changes in the piriformis muscle was not stated. Kipervas and associates50 establish the location Eight (35%) showed spontaneous resting activity for palpating the piriformis muscle through the in the involved piriformis muscle, indicating a skin somewhat differently. They select the junc- tendency first to develop muscle spasm. tion of the middle and lower thirds of a line Eleven patients (48%) had a low discharge rate drawn between the anterior superior iliac spine on voluntary contraction (25-30 Hz), compared and the ischiococcygeus muscle. with a normal value of 50-70 Hz in the contralat- If any doubt exists as to the cause of tenderness over the greater sciatic fora- eral uninvolved piriformis and the overlying ipsi- men, the medial end of the piriformis should be palpated within the pelvis by lateral gluteus maximus.50 The mean motor unit the rectal or vaginal r o u t e . 1 1 , 5 0 , 5 2 , 6 9 , 7 1 , 8 5 , 1 0 0 This examination is performed more duration for the involved piriformis muscles was readily if the examiner has a long finger (Fig. 10.5). The technique is also illus- significantly increased to 7 millisec (normal side trated by Thiele.100 The patient is placed side lying with the affected side upper- 6.3 millisec) (p < 0.01). These changes are charac- most and with that knee and hip flexed. The transversely oriented sacrospinous teristic of neuropathy. On the other hand, 15 (65%) of involved mus- cles produced low amplitude motor unit action potentials of only 80 uV (normal 4 5 0 (uV). The amplitude range of interference pattern EMG was decreased to 1 0 7 - 1 9 0 |xV (normal side 1 6 6 - 2 7 6 uV). These changes are more likely to be seen in myopathic diseases, unless the potentials were

200 Part 1 / Lower Torso Pain Sacrotuberous ligament Iliolumbar ligament L4 nerve root (cut) Ventral sacroiliac L5 nerve root ligament S1 nerve root Greater sciatic foramen S2 nerve root Piriformis Lumbosacral muscle (cut) plexus Coccygeus Piriformis muscle (cut) muscle Sacrospinous Coccygeus ligament muscle Lesser sciatic Piriformis foramen tendon Inguinal Sacrotuberous ligament ligament Obturator Iliococcygeal Rectum Vagina internus portion of muscle levator ani Pubococcygeal portion of Urinary levator ani muscle bladder Sciatic nerve muscle (cut) Tendinous arch of levator ani Iliococcygeal portion of levator ani muscle Figure 10.5. Internal palpation of the left piriformis identified by the palpating finger before it reaches the piriformis muscle. The sacrospinous ligament attaches muscle (dark red within the pelvis and light red cephalad mainly to the coccyx, which is usually easily outside the pelvis) via the rectum, viewed from in front palpated and mobile. The posterior wall of the rectum and above. The levator ani is medium red; the coc- and the S3 and S4 nerve roots lie between the palpat- cygeus and obturator internus muscles are light red. ing finger and the piriformis muscle. The sacrospinous ligament (covered by the coc- cygeus muscle) is the last major transverse landmark produced by recently reinnervated motor units. for this tenderness, it can be palpated di- The gluteus maximus did not show any of these rectly by rectal or vaginal examination, as changes.50 described in Chapter 6. The thickness of the involved piriformis muscle Figure 10.3 reminds one that the sciatic in a patient scheduled for operation was esti- nerve is also compressed as pressure is mated to be 11 mm by measuring the depth of applied medial to a point midway be- penetration of the needle through which volun- tween the greater trochanter and the tary motor unit activity was observed. This esti- ischial tuberosity. The nerve usually mate was proven accurate at operation.50 emerges between the piriformis and supe- rior gemellus muscles and continues its Gemelli and Obturator Internus course superficial to the superior gemel- lus, obturator internus, inferior gemellus, Figure 10.3 shows that, in the anatomical obturator externus, and quadratus femoris position, all of the piriformis muscle lies muscles. above the level of its attachment to the uppermost part of the greater trochanter. Quadratus Femoris and Obturator Externus Deep tenderness (deep to the gluteus maximus) inferior to the piriformis—at Figure 10.3 shows that deep tenderness the level of and medial to the upper one- medial to the lower two-thirds of the third of the greater trochanter—is most greater trochanter probably arises in the likely tenderness of one of the gemelli or quadratus femoris or, possibly, in the of the obturator internus muscle. If TrPs even deeper obturator externus muscle. in the obturator internus are responsible The sciatic nerve may also be tender.

Chapter 10 / Piriformis and Other Short Lateral Rotators 201 Figure 10.6. Four routes by which por- tions of the sciatic nerve may exit the pelvis: (1) the usual route, in which all fi- bers of the nerve pass anterior to the pir- iformis between the muscle (red) and the rim of the greater sciatic foramen, seen in about 8 5 % of cadavers; (2) the peroneal portion of the nerve passes through the piriformis muscle and the tib- ial portion travels anterior to the muscle, as seen in more than 10% of cadavers; (3) the peroneal portion of the sciatic nerve loops above and then posterior to the muscle and the tibial portion passes anterior to it; both portions lie between the muscle and the upper or lower rim of the greater sciatic foramen, as seen in 2 - 3 % of cadavers; (4) an undivided sci- atic nerve penetrates the piriformis mus- cle in less than 1% of cadavers. (After Beaton and Anson,14 with permission.) Tenderness due to TrPs in the obturator (faster conducting) fibers were selectively externus muscle may be detected also in susceptible to pressure. In these relatively the groin. One must first palpate the su- brief experiments, loss of circulation was perficial pectineus and adductor brevis to not responsible for the nerve conduction confirm that they do not harbor tender loss; stagnation of blood flow without TrPs that would obscure a deeper source nerve compression did not measurably af- of tenderness. Deep pressure is then ap- fect neural conduction for up to 2 hours.28 plied between the pectineus and adductor These experimental observations are con- brevis against the outer surface of the ob- firmed clinically for both motor and sen- turator membrane, which is covered by sory nerves when one tries to get up after the obturator externus muscle. sitting immobile for too long on a hard toilet seat. 10. ENTRAPMENTS (Fig. 10.6) The value of nerve conduction studies that examine the segment that passes Conduction of compound action poten- through the greater sciatic foramen was tials by the sciatic nerve is remarkably demonstrated by Nainzadeh and Lane.67 sensitive to gentle but prolonged pres- Although routine EMG studies of root sure.28 In rabbits, these compound action levels L3 through S1 were normal, so- potentials of the intact sciatic nerves de- matosensory-evoked potential studies of creased to 50% of initial value after the root levels S2 through S4 by stimulation of application of only a 10-g (1/6-oz) weight the pudendal nerve showed increased directly to the nerve for 45 minutes. The P40(P1) latencies of 47 millisec. This led response decreased also to 50% after a to the diagnosis of piriformis muscle syn- sustained application of 20 g (1/3 oz) for a drome. Tenolysis of the piriformis muscle shorter time, 10—15 minutes. The larger relieved the patient's symptoms and the

202 Part 1 / Lower Torso Pain Table 10.1. How Often the Peroneal and Tibial Portions of the Sciatic Nerve Go Around or Through the Piriformis Muscle (Percent of Limbs) Authors Both* Peroneal** Peroneal*** Both**** Both Peroneal Number Below through above, through (%) above (%) above, of limbs Muscle (%) Tibial Tibial Tibial through (%) below (%) below (%) Anderson8 87.3 12.2 0.5 00 0 640 Beaton and 90 7.1 2.1 0.8 0 0 240 Anson14 Beaton and 89.3 9.8 0.7 0.2 0 0 2250 Anson13 Lee and Tsai52 70.2 19.6 1.5 1.8 3 1.2 168 Pecina72 78.5 20.7 0.8 00 0 130 * Illustrated in Panel 1 of Fig. 10.6. ** Illustrated in Panel 2 of Fig. 10.6. *** Illustrated in Panel 3 of Fig. 10.6. ****Illustrated in Panel 4 of Fig. 10.6. P40(P1) response returned to a normal la- greater sciatic foramen. Those affected tency of 40 millisec. Synek97, 98 established structures are described in Section 2, and the diagnosis of piriformis syndrome by the symptoms attributable to the resulting evidence of chronic denervation of the compression are covered in Section 6. muscles in the nerve distribution below The vulnerable structures include the su- the sciatic notch, with slowing and perior gluteal, inferior gluteal, and pu- decreased amplitude of somatosensory dendal nerves and vessels; the sciatic and evoked potentials from those nerves in posterior femoral cutaneous nerves; and the portion passing through the greater the nerves supplying both gemelli, the sciatic foramen. The authors of these pa- obturator internus, and the quadratus pers apparently had not explored the pos- femoris muscles. sibility (and likelihood) of myofascial TrPs causing these piriformis syndromes. Figure 10.6 depicts the second kind of entrapment that would depend on varia- Two kinds of entrapments may occur as tions in how the sciatic nerve passes be- part of the piriformis syndrome: vascu- side or through the piriformis muscle. Ta- lar41 or nerve41,436,6,72 entrapment between ble 10.1 summarizes reports documenting the piriformis muscle and the rim of the these variations. Generally, the peroneal greater sciatic foramen and, possibly, division of the sciatic nerve has been re- nerve entrapment within the mus- ported to penetrate the muscle in 10—20% of limbs, probably about 11%. c l e .8 5 , 8 9 , 1 0 6 Table 10.2 summarizes nine papers that The first kind of entrapment has been report 40 piriformis operations with 35 well documented at surgery for the sciatic confirmed as piriformis syndrome by re- nerve194 and for the superior gluteal lief of symptoms. Two patients were de- nerve78 (see Section 6). Freiberg41 noted scribed as having engorgement of the that a rich vascular plexus from the infe- veins distal to the foramen;1 two reports rior gluteal vessels lies between the sci- described thinning of the sciatic nerve at atic nerve and the piriformis muscle. the foramen with distal swelling;194 and Compression within the greater sciatic fo- two surgeons noted tightness that pre- ramen could cause distal venous engorge- vented probing into the greater sciatic fo- ment of the sheath of the trunk of the sci- ramen.178 None of the papers noted pas- atic nerve, which he observed at opera- sage of any part of the sciatic nerve tion. Both the blood vessels and nerves through the substance of the piriformis were subject to compression by the piri- muscle. Of the 40 case reports describing formis muscle as they passed through the

Chapter 10 / Piriformis and Other Short Lateral Rotators 203 Table 10.2. in nerve configuration, for the cases re- Reports of Operative Treatment of Piriformis Syn- ported in Table 10.2 one would have ex- dromes and Relation of Sciatic Nerve to the Piri- pected to see about four (4.4) variant sci- formis Muscle as it Exits Pelvis atic nerve configurations among the 40 surgical cases. The fact that none was re- Source Number Nerve ported raises a question as to whether the of position variant configurations through the muscle may be protective of the nerve rather than muscles a source of entrapment. Taut bands of muscle are probably more resilient than 1934 Freiberg and Vinke40 1 Below the unyielding bony and ligamentous fo- ramen boundaries. 1 NR A similar variation in the pathway of 1937 Freiberg41 12 NR the inferior gluteal nerve has also been observed. The inferior gluteal nerve pene- 1976 Mizuguchi64 14 NR trated the piriformis muscle on its way to the gluteus maximus muscle in 8.9% of 1976 Kipervas et al.50 1 Below 224 limbs.101 1980 Adams1 4 Below The posterior branch of the obturator nerve normally reaches the thigh by 1980 Rask78 1 AR piercing the obturator externus mus- cle.23,24 This branch supplies the obturator 1981 Solheim et a l . 9 3 2 AR externus as it penetrates the muscle, and, as the nerve terminates, it supplies the 1983 Stein and Warfield94 1 AR adductor magnus and part of the adductor brevis muscle.24 Entrapment of this nerve 1988 Cameron and Noftal17 3 NR might be caused by taut TrP bands in the obturator externus muscle, but no case is NR - No remarks about the sciatic nerve in report. known in which this entrapment was AR - Appearance of nerve reported, but anatomical configura- identified clinically. tion not stated. 11. ASSOCIATED TRIGGER POINTS surgical sectioning of the piriformis mus- cle, normal anterior passage of the nerve The piriformis rarely presents as a single- deep to and inferior to the muscle was ex- muscle pain syndrome. TrPs in this mus- plicitly described in five patients;1,40,50 an- cle are most likely to be associated with terior passage was implied in one;1 fifteen TrPs in adjacent synergists. The posterior operations were described as freeing the part of the gluteus minimus is nearly par- sciatic nerve with no comment on a vari- allel to and attaches close to the attach- ant pathway.50,64,93 For the remaining 19 ments of the piriformis muscle. Adjacent, operations, no mention was made of the on the lower edge of the piriformis, lie nerves. It is considered unlikely that a three of the lateral rotator group: the two surgeon would section the piriformis gemelli and the obturator internus. Pace muscle before locating all of the sciatic and Nagle71 noted the concurrent involve- nerve. It also seems unlikely that a variant ment of these latter muscles and also configuration of the nerve would have warned that the levator ani and coccygeus been observed and not reported. Many of muscles are commonly involved with the the papers on this subject by surgeons piriformis muscle. The piriformis fibers make special note of how frequently part that are attached to the lower sacrum or all of the sciatic nerve passes through sometimes intermingle with the coc- the belly of the piriformis muscle in ana- cygeus fibers when the latter fibers cover tomical studies, but apparently none of the sacrospinous ligament. these variations was a factor in the pa- tients who obtained relief by sectioning When multiple gluteal muscles are in- the piriformis muscle. volved, piriformis spot tenderness may not be apparent until TrPs in the overly- These surgical reports suggest that ana- ing gluteus maximus and in the posterior tomical variations in the position of the nerve may, contrary to the usual opinion, possibly reduce the risk of compression. Accepting an incidence of 11% variation

204 Part 1 / Lower Torso Pain Figure 10.7. Stretch position and intermittent cold uppermost thigh is flexed nearly 90° at the hip. The patient anchors the greater trochanter by holding the pattern (parallel lines with thin arrows) for TrPs in the distal thigh down against the table, assisted by gravity, right piriformis muscle. The thick arrows show the di- while the operator progressively adducts the thigh at rections of force exerted by the operator and by the the hip by pulling backward on the crest of the ilium. patient. The open circle marks the greater trochanter. The Xs mark the regions where TrPs are located. The fibers of the adjacent gluteus medius and of rotation of the hip joint, it changes gluteus minimus muscles have been inac- from a lateral rotator to an abductor of the tivated. However, a rectal or vaginal ex- thigh when the hip is flexed to 90°. The amination should reveal tenderness at the best leverage on and the most effective medial end of the piriformis muscle. stretch of the piriformis are obtained when the muscle is lengthened by ad- 12. INTERMITTENT COLD WITH ducting the thigh with the hip flexed to STRETCH 90° (Fig. 10.7). (Figs. I0.7 and 10.8) Figure 10.7 illustrates the single-opera- Stretching of the piriformis muscle aug- tor, patient-assisted passive stretch tech- mented by vapocoolant spray or ice appli- nique for intermittent cold with stretch of cation has been found by the authors and the piriformis muscle. The patient lies on by others11 to be effective in the manage- the uninvolved side with the uppermost ment of the piriformis syndrome. Because thigh flexed to a right angle. The clinician of ozone layer concerns, the use of Fluori- pulls back on the pelvis while the subject Methane as the vapocoolant spray has assists by pushing down on the distal been questioned and alternatives recom- thigh of the side being treated. The opera- mended.91 Details of the original stretch- tor applies several parallel sweeps of ice and-spray technique are found on pages or vapocoolant spray from the TrP distal- 63-74 in Volume 1 of this manual; a ward over the muscle and over the pain method of substituting ice for vapocool- pattern as shown in Figure 10.7. It is not ant spray appears on page 9 in Chapter 2 necessary to extend sweeps of intermit- of this volume. tent cold below the knee to cover an area of pain caused by nerve entrapment, but Since the piriformis muscle is primar- only as far as the muscle's referred pain ily a lateral rotator of the thigh together pattern extends down the thigh. with the other five short lateral rotators, all can be stretched by medial rotation of The intermittent cold-with-stretch pro- the thigh with the hip straight, as illus- cedure can be effectively combined with trated by Evjenth and Hamberg.33 How- postisometric relaxation, as described be- ever, because the piriformis tendon at- low and in Chapter 2 on page 11. Vapo- taches to the femur at the level of the axis coolant spray has been recommended by other authors for facilitating the release of

Chapter 10 / Piriformis and Other Short Lateral Rotators 205 tension in this muscle.95,99 Steiner and as- Retzlaff and associates80 recommended sociates95 recommended ethyl chloride several stretch techniques including re- spray to those who prefer its more rapid ciprocal inhibition, which, for the piri- cooling effect and Fluori-Methane to formis, is most effectively done by con- those who prefer the safety of its non- tracting the antagonistic medial rotator flammability (and non-anesthetic effect) muscles without allowing any medial ro- for inactivation of piriformis TrPs. We ex- tation movement of the thigh, and then af- pect Fluori-Methane to be replaced by a ter relaxation, passively taking up the comparable, but environmentally safe slack in the piriformis by increasing me- product. dial rotation. Reciprocal inhibition can be alternated with postisometric relaxation, Intermittent cold with stretch is and the intermittent cold applied during repeated until full muscle length is the relaxation and take-up-slack phase. achieved or until no further gains are ap- parent. The skin is rewarmed with a The technique of postisometric relaxa- moist heating pad and the thigh actively tion reported by Lewit and Simons55 is moved through full adduction-abduction similar in principle to that described as while it is flexed 90°, and through full contract-relax by Voss et al.107 and is medial and lateral rotation when the hip described in detail in Chapter 2. is straight. Postisometric relaxation is facilitated in the piriformis muscle by coordinating Prompt reactivation of piriformis TrPs the gentle voluntary contraction phase following a good response to intermittent (against the resistance of gravity) with in- cold with stretch (or injection) may be halation while looking up, and coordinat- due to associated displacement of the SI ing the relaxation phase with exhalation joint. This displacement must be cor- while looking down.54 This facilitation rected by mobilization of the joint (Chap- technique may be used alone or with the ter 2). Several patients, immediately fol- application of intermittent cold during lowing restoration of normal function of the relaxation phase. both the SI joint and the piriformis mus- cle, developed acute subcostal pain along Some clinicians may prefer alternative stretch the lower margin of the rib cage in the vi- cinity of the diaphragm. Each of these pa- positions that have been recommended by other tients exhibited paradoxical breathing90,104 and responded to myofascial release pro- authors. The stretch technique for the piriformis cedures that lifted the lower rib cage up and outward, exerting traction on the lat- described and illustrated by Lewit53 affects all eral abdominal wall muscles and the dia- phragm. short lateral rotators. For this method, the patient Stretch Techniques is placed prone with the hip extended and the Effective stretch or massage for treatment knee flexed. As the foot swings outward, the leg of any muscle with myofascial TrPs de- pends strongly on the completeness of the provides gravity-assisted medial rotation of the patient's relaxation achieved before and during elongation of the muscle. Recipro- thigh. This approach stretches all of the short lat- cal inhibition and contract-relax are effec- tive relaxation techniques. Postisometric eral rotators including the piriformis. In this tech- relaxation combines both relaxation and muscle elongation. nique, the knee is vulnerable to injury if pressure Massage may be considered a form of is applied to the foot or ankle to assist stretch. An- localized stretch in the region of the TrP. It is most effective for inactivation of TrPs other technique illustrated by Evjenth and Ham- if the muscle is passively lengthened to the point of taking up all of the slack but berg33 applies adduction to the thigh with the pa- remains fully relaxed. tient supine and with both the hip and knee flexed. This position has the advantage of placing the hip in flexion and provides a convenient method of self-stretch. However, it loses some of the assistance by gravity and makes the referred pain pattern inaccessible to the application of va- pocoolant or ice. Following ischemic compression of the piri- formis muscle using the elbow method (see be- low), TePoorten99 placed the patient supine and flexed the affected leg on the thigh and the thigh on the abdomen; he then straightened the lower limb while adducting the thigh. After repeating

206 Part 1 / Lower Torso Pain Figure 10.8. Ischemic compression by bimanual thumb pressure to inactivate a TrP in the lateral part of the right piri- formis muscle, the upper marginal fibers of which lie deep to the dotted line. The uppermost thigh is flexed. The thumb is placed slightly lateral to the junction of the lateral and middle thirds of the dis- tance from the greater trochanter (open circle) to the border of the sacrum (solid line). Firm application of pressure toward the femur is usually required to project force (thick arrow) through the overlying gluteal muscles, which must remain fully relaxed for this technique to be effective. Meanwhile, increasing slack in the piri- formis muscle is taken up by adducting the thigh to the limit of the patient's com- fort and by asking the patient to hold the knee to prevent it from moving while the operator maintains backward traction on the pelvis. The clinician should avoid pressure that produces tingling in the lower limb due to nerve compression. this two or three times, he found that it often cor- Direct digital pressure has been applied rected pelvic and lower limb-length imbalance rectally on rigid tender piriformis muscles and relieved the piriformis syndrome. near the medial attachment of the muscle and complete pain relief reported.44 Effec- Julsrud48 presented a case report of a female ath- tiveness of these compression techniques is lete with piriformis syndrome who, with daily improved if the muscle is placed on moder- stretching exercises of the piriformis muscle, re- ate stretch during treatment. sumed running without pain. Ischemic Compression Massage (Fig. 10.8) In 1937, Thiele100 described internal mas- Ischemic compression may be applied ex- sage of the piriformis muscle. With full- ternally, as described in Volume l , 1 0 4 length insertion of the finger in the rectum, with the addition that, for the piriformis, the fibers of the piriformis are felt immedi- pressure is applied bimanually with the ately beyond (superior to) the sacrospinous thumbs (Fig. 10.8) over each area of TrP ligament. Lateral motion of the finger pro- tenderness in the muscle. These areas are ceeds lengthwise on that portion of the located beginning at the lateral end of the belly of the muscle lying within the pelvis. muscle, to avoid applying pressure on the The massage is begun lightly to avoid irri- sciatic nerve. Other authors31,80,99 have de- tating extremely tender tense muscles. In scribed and illustrated80 the application subsequent treatments, the massage pres- of external pressure on piriformis TrPs by sure is increased. If increased pain is expe- the bent elbow. This technique is attrac- rienced, the clinician returns to lighter tive because it provides strong leverage, massage; pressure is increased as ten- but it may be hazardous because it derness subsequently decreases. Muiller65 reduces the operator's sensation of under- strongly recommended this method of lying structures and increases the risk of treatment for the piriformis syndrome. injuring the sciatic nerve. If this elbow technique is used, it should be used with Other Methods of Treatment caution in this region. Hallin43 reported that six to ten ultra- sound treatments over the tender piri-

Chapter 10 / Piriformis and Other Short Lateral Rotators 207 formis muscle at 13/4-2 W/cm2 for 5-6 Figure 10.9. Injection of TrPs in the right piriformis minutes daily usually relieved the piri- muscle. The open circle locates the greater trochan- formis syndrome pain in 2 weeks. Some ter; the doffed line, the palpable margin along the physical therapists have found a special edge of the sacrum; and the solid line, marked in transvaginal ultrasound applicator effec- thirds, overlies the upper (cephalad) margin of the piri- tive. Barton et al.11 recommended ultra- formis muscle. A, injection of TrP1 using the usual, sound therapy prior to stretching the piri- completely external, approach. S, injection of TrP2 us- formis muscle. ing a bimanual technique. The left hand locates the trigger-point tenderness via intrapelvic palpation, and Shortwave diathermy was reported to the right hand directs the needle toward that fingertip. be helpful in conjunction with a full course of physical therapy.47 Clinical ex- nerve trunk. The inactivation of the lat- perience (Personal communication, Mary eral TrP1 may also eliminate TrP2 activity. Maloney, P.T.) has shown that pulsed dia- thermy (Magnatherm Model 1,000. Inter- Lateral Trigger Point (TrP1) national Medical Electronics, Ltd., 2805 Main, Kansas City, MO 64108) applied in To inject the more lateral TrP1 (Fig. sequential 10-minute periods of relatively 10.9A), the patient lies on the uninvolved high, low, high intensity is a valuable side with the uppermost thigh flexed to substitute in deeply placed muscles for a approximately 90°. The superior border of heating pad following intermittent cold the piriformis muscle is located by mark- with stretch. This is most useful in severe ing a line (see Figure 8.5) that runs from acute myofascial TrP syndromes when all just above the greater trochanter to the intensities must be reduced. As recovery point where the palpable border of the progresses and the patient's tolerance in- creases, or in chronic myofascial pain syndromes, it becomes preferable to use the pulsed diathermy with a moving head technique at a sustained higher level with appropriate precautions (Personal com- munication, Mary Maloney, P.T.). For diathermy to be effective, one would expect that it must increase circu- lation proportionately more than it in- creases metabolism in the region of the TrP. Studies are needed to determine the specific effects of diathermy on TrPs. Reconditioning exercises for the piri- formis should follow stretch therapy. One such exercise is described in Section 14 of this chapter. 13. INJECTION AND STRETCH (Fig. I0.9) Piriformis Muscle Details of the examination technique for locating piriformis TrPs are found in Sec- tion 9 of this chapter. Details of the injec- tion technique are presented in Section 13 of Chapter 3 in Volume l . 1 0 4 The lateral TrPs located in the TrP1 area should be injected before injecting those in the medial TrP2 area. The lateral TrPs are readily reached externally through the skin and are not in the vicinity of a major

208 Part 1 / Lower Torso Pain sacrum encounters the ilium at the inferior viously, to eliminate any TrPs that may border of the sacroiliac joint. This piri- have been missed. This is followed by ac- formis line, shown in Figure 10.9, is di- tive range of motion, with the patient vided into thirds and the piriformis mus- slowly fully shortening and then fully cle is palpated just inferior to it for tender lengthening the muscle by moving the spots, as described in Section 9, Trigger thigh through medial and lateral rotation Point Examination. The TrP1 area is lat- with the hip straight. This is repeated two eral and just inferior to the junction of the or three times to reestablish full range of lateral and middle thirds of the piriformis motion and normalize muscle function. A line. When an active TrP is located, appli- moist heating pad is then applied to cation of digital pressure usually repro- rewarm the skin. duces the myofascial portion of the pa- tient's pain distribution. The spot tender- Others95,99 have also recommended ness of the most sensitive TrP is localized treating the piriformis syndrome by in- between the fingers of the palpating hand. jecting TrPs or tender spots in this lateral musculotendinous portion of the muscle. Usually a 22-gauge, 50-mm (2-in) nee- dle is used on a 10-mL syringe for the lat- Medial Trigger Point (TrP2) eral TrP location. In a thin person, a 22- gauge, l1/2-inch needle may be sufficient The authors recommend that injection of to reach through the skin, gluteus max- TrPs in the medial TrP2 region be accom- imus, and piriformis muscle to the joint plished bimanually. One finger palpates capsule. This depth of penetration is nec- the inner surface of the medial third of essary to ensure penetrating all of the the piriformis muscle using the rectal or TrPs in this portion of the piriformis mus- vaginal route; the other hand inserts the cle. In obese patients, a longer 63- to 75- needle externally, directing the needle to- mm (21/2- to 3-in) needle may be required. ward the intrapelvic palpating fingertip, A solution of 0.5% procaine is prepared and injects the local anesthetic solution. by diluting 2% procaine with isotonic sa- With sufficient finger-reach, it is possible line for injection. to palpate both the pelvic inner surface of the piriformis muscle and the pelvic sci- When the TrP tenderness has been lo- atic nerve against the sacrum, as well as calized, the needle is inserted through the the area of the greater sciatic foramen. skin directly toward the point of maxi- mum tenderness. In pain-sensitive pa- Namey and An68 emphasized that when tients, dribbling a small amount of pro- a long-acting local anesthetic is injected, caine solution during progression of the the physician should warn the patient of needle minimizes pain when the TrP is possible numbness and weakness in the encountered. When a TrP is impaled, the distribution of the sciatic nerve following region several millimeters to either side injection. The patient should not leave of and above and below the TrP is then unassisted nor attempt to drive a car until explored by peppering with the needle in any such local anesthesia has disap- probing steps, searching for additional peared. When using 0.5% procaine, nerve TrPs in that vicinity. Needle encounter block rarely lasts longer than 20 minutes. with a TrP is recognized by the pain re- sponse of the patient, and particularly if Others16,69,71,95 have recommended injection of the encounter reproduces the patient's re- ferred pain. Penetration of the TrP is con- the piriformis near the lateral border of the sac- firmed when the needle evokes sharp pain and a local twitch response of the rum. Pace69 described passing a long spinal needle muscle. just below the edge of the ilium and encountering Before withdrawing the needle com- pletely, the skin at its entry point is slid the piriformis muscle as it exits through the to one side and the area is palpated for deep tenderness to ensure that no resid- greater sciatic foramen. He guided the direction of ual TrPs remain. the needle by a finger that was palpating the TrP Following injection, intermittent cold with stretch is applied, as described pre- through the vagina or rectum and aimed the nee- dle at the finger until he could feel the needle dis- tend the tissues over the TrP. We localize the TrP in the same way. Pace69 then injected 1% lidocaine and waited 5 minutes to establish that the sciatic nerve had not

Chapter 10 / Piriformis and Other Short Lateral Rotators 209 been infiltrated and that the patient was not ex- drome.64,93 If symptoms are caused by periencing a pins-and-needles sensation down the myofascial TrPs, then surgery is unnec- leg. Then, he injected 6 mL of a mixture contain- essary as shown by recent reports of ing 4 mL of 1% lidocaine and 2 mL (20 mg) of tri- successful medical treatment of the piri- amcinolone acetonide.71 We inject only 0.5% pro- formis s y n d r o m e . P a c e1 5 , 4 3 , 6 8 , 6 9 , 7 1 , 9 4 , 9 5 , 1 0 9 caine and, therefore, need no 5-minute waiting stated unequivocally, \"surgical resec- period. tion is not i n d i c a t e d ; \" 6 9 Barton et al. consider it the last resort.11 As described previously, Pace recommended a long spinal needle.69 We also find that, for this ap- Other Short Lateral Rotators proach, a 75- or 90-mm (3- or 31/2-in) spinal needle is required in most patients. It was the clinical im- No literature was found that described pression of Pace and Nagle71 that the addition of the identification and injection of TrPs in corticosteroid provided more complete and more the remaining five short lateral rotators. lasting relief. We prefer to inject only 0.5% pro- When TrPs occur there, the location is es- caine, since accidental infiltration of the nerve tablished as described in Section 9. For with this solution causes only transient paresthe- practical purposes, localization to a spe- sia and weakness. With either technique, the nee- cific muscle is not necessary and one dle must be replaced immediately if it encounters need only distinguish two groups of mus- bone that curls the tip of the needle to produce a cles: the two gemelli and the lateral part hook. A hook on the needle produces a scratchy of the obturator internus compose one sensation of roughness when the needle is with- group; the quadratus femoris and the un- drawn even slightly. derlying obturator externus compose the other. Gynecologists may prefer to use a paravaginal approach.16,71, 109 Wyant109 notes that the muscle is When TrP tenderness is identified in easier to reach for examination in the female using one of these muscle groups and injection the vaginal rather than the rectal route. He de- is deemed necessary, the physician must scribed a method of introducing the needle consider the path of the sciatic nerve as it through the perineum medial to the ischial tuber- crosses over these muscles, usually mid- osity and advancing it paravaginally under tactile way between the ischial tuberosity and control into the piriformis TrP. It is also possible the greater trochanter (Fig. 10.3). Tender- to reach the piriformis from the lateral fornix of ness of taut bands caused by piriformis the vagina, by an approach similar to that for TrPs extends almost horizontally across paracervical block. Wyant109 recommended injec- the lower buttock. Tenderness of the sci- tion of 8 mL of 0.5% lidocaine mixed with 80 mg atic nerve extends vertically along the of triamcinolone. path of the nerve. Among the 84 patients with piriformis syn- The lateral (peroneal) portion of the sci- drome who received injections of 10-mL of 0.5% atic nerve can be located precisely in or- solution of procaine,75 55% of them had prompt der to avoid it during injection by observ- amelioration of angiospastic signs and symptoms. ing motor responses to stimulation of the The lower extremity oscillogram improved and anterior tibial nerve in the region of the the chilly feeling in the leg disappeared. In many, injection site. Either a magnetic ring or an weak Achilles reflexes were restored and the ex- EMG needle can be used for stimulation. tent and intensity of hypalgesia were improved. The former is not invasive and is less painful. A Teflon-coated hypodermic nee- Surgical Release dle of the type used for motor point blocks can be used both for localized Having first41 reported surgical release stimulation and then injection at another of the muscle, Freiberg later42 expressed location. Sensory response is unreliable. frustration with a lack of rationale for Stimulation of a TrP elicits pain in its re- this procedure. Since histological exam- ferral pattern, which, in these muscles, ination of surgical specimens showed may mimic neurogenic pain. no abnormality, he assumed that the muscle was not primarily responsible. The technique for injection of these He was, however, apparently unaware muscles is essentially the same as that de- of myofascial TrPs. Surgical release scribed for the TrP1 area in the lateral part is still performed for piriformis syn-

210 Part 1 / Lower Torso Pain Figure 10.10. Correct lower-limb position to improve would place painful stretch on a tense piriformis, as well as on other short lateral rotator, and/or tense glu- sleep when lying on the unaffected side. A pillow is teal muscles. placed between the knees and ankles in order to avoid adduction of the uppermost thigh at the hip, which of the piriformis, except that one selects a avoided by those prone to piriformis more distal location of needle entry. TrPs. 14. CORRECTIVE ACTIONS When sitting at home or at work, the (Figs. 10.10 and 10.11) patient should be instructed to change position often. The use of a rocking chair Body Asymmetry helps to prevent immobility of the mus- cles, including the piriformis, for pro- Whenever a lower limb-length inequality longed periods of time. or a small hemipelvis produces a com- pensatory functional scoliosis, the ine- Mechanical Stress quality should be corrected. A heel (shoe) lift, as noted by Hallin,43 corrects the for- The patient with an involved piriformis mer and an ischial (butt) lift, as described muscle should be warned against either on pages 77—78 in Chapter 4 , corrects the making a strong lateral rotatory effort or latter. See Chapter 4 for a review of the the braking (restraining) of strong medial relation between lower limb-length ine- rotatory momentum when bearing weight qualities and pelvic distortions. on the involved limb. Such strong rota- tions often occur when a person plays Postural and Activity Stress vigorous tennis, soccer, or volleyball, or (Fig. 10.10) engages in competitive running; these ro- tations are likely to reactivate piriformis When sleeping on the side, the patient TrPs. should place a pillow between the knees with the support extending to the ankles In 1 9 4 7 , the senior author and her fa- to avoid prolonged adduction at the hip ther106 reported the importance in some with the thigh flexed, which may pain- patients of reducing sacroiliac displace- fully stretch the taut piriformis muscle ment in addition to inactivating the piri- and seriously disturb sleep. The recom- formis TrPs to achieve lasting relief. More mended position is illustrated in Figure recently, Hinks44 emphasized that when sacroiliac subluxation occurs together 10.10. with the piriformis syndrome, both the subluxation and the muscle tension must The patient who has myofascial syn- be restored to normal. dromes of these lateral rotator muscles should avoid prolonged immobilization The presence of a Morton foot structure of the involved lower limb when driving (mediolateral rocking foot) should be a car for a long distance; this can be ac- identified and corrected as described in complished by stopping and walking Sections 8 and 14 of Chapter 2 0 , to avoid briefly every 2 0 - 3 0 minutes. Sitting on imposing repetitive compensatory strain one foot can aggravate TrPs in the hip on the lateral rotator muscles of the hip. muscles on that side and should be

Chapter 10 / Piriformis and Other Short Lateral Rotators 211 Figure 10.11. Self-stretch of the right piriformis mus- form postisometric relaxation, the individual then at- cle. The right thigh is flexed nearly 90° at the hip with tempts to abduct the thigh by pressing it gently against the right foot on the treatment table. To adduct the the resisting left hand for a few seconds (isometric thigh at the hip, pressure is exerted downward with contraction of abductors), then relaxes and gently both hands (large arrows), one on the thigh and the moves the thigh into adduction, which gradually other on the pelvis, pulling against each other. To per- lengthens the piriformis muscle. Attention should also be given to other A tennis ball may be used for self-appli- causes of a hyperpronated foot. cation of ischemic compression to the pir- iformis muscle while side lying in a man- Self-therapy ner similar to that described in Section 14 (Fig. 10.11) of Chapter 8 for the gluteus medius mus- cle and as shown in Figure 8.9. This treat- We have found, as have others,11 that a ment can be helpful for lateral piriformis home program of prolonged piriformis TrPs and for the other five short lateral ro- stretching can be essential for complete tators. The tennis ball must be placed far and lasting relief. To perform the piri- enough laterally (anteriorly) to avoid the formis muscle passive self-stretch, the su- sciatic nerve where pressure causes pine patient (Fig. 10.11) crosses the leg of numbness and tingling below the knee. the involved side over the opposite thigh, and rests the opposite hand on the knee Steiner and associates95 describe and il- of the uppermost affected limb. This hand lustrate a valuable \"loosening\" exercise is used, when needed, to assist gravity in in which the standing patient performs a adducting the involved thigh, which is rhythmic full rotation of the hips, letting flexed about 90°. The patient stabilizes the trunk and arms loosely follow. They the hip on the involved side by pressing recommend performing this exercise down on the iliac crest with the ipsilat- three to six times (every few hours) eral hand. Release of muscle tension is throughout the day. augmented by the patient \"thinking\" of gently lifting the weight of the adducted Stretching of the piriformis should be leg (but not moving it) during slow in- followed by reconditioning exercises, halation; then, during slow exhalation, starting with the subject lying on the un- having the muscle \"let go\" and allowing affected (\"normal\") side with the upper- the piriformis to elongate, as described by most (affected) thigh flexed to 90°. It is Lewit.54,55 particularly beneficial if an assistant can first passively abduct the patient's thigh Saudek84 illustrates a side-lying version and then allow the patient to lower the of piriformis self-stretch similar to the su- thigh slowly to the treatment table, acti- pine technique described above. She also vating the piriformis in a lengthening illustrates self-stretch of this muscle in contraction. Using this same position, the seated position. progression can be made to shortening contractions by active abduction of the

212 Part 1 / Lower Torso Pain flexed thigh against the resistance of grav- 30. Dye SF, van Dam BE, Westin GW: Eponyras ity. and etymons in orthopaedics. Contemp Orthop References 6:92-96, 1983. 31. Edwards FO: Piriformis Syndrome. Academy of 1. Adams JA: The piriformis syndrome—report of four cases and review of the literature. S Afr J Osteopathy Yearbook, 1962 (pp. 3 9 - 4 1 ) . Surg 1 8 : 1 3 - 1 8 , 1 9 8 0 . 32. Ehrlich GE: Early diagnosis of ankylosing 2. Anderson JE: Grant's Atlas of Anatomy, Ed. 8. Williams & Wilkins, Baltimore, 1983 (Fig. 3- spondylitis: role of history and presence of 12). HLA-B27 Antigen. Internal Medicine for the Spe- cialist 3 ( 3 ) : 1 1 2 - 1 1 6 , 1982. 3. Ibid. (Fig. 3 - 5 5 ) . 33. Evjenth O, Hamberg J: Muscle Stretching in Man- 4. Ibid. (Fig- 3 - 7 3 ) . ual Therapy, A Clinical Manual, Vol. 1, The Ex- 5. Ibid. (Fig. 4 - 3 2 A ) . 6. Ibid. (Fig. 4 - 3 6 ) . tremities. Alfta Rehab F0rlag, Alfta, Sweden, 7 . Ibid. (Fig. 4 0 ) . 8. Ibid. (Fig. 4 - 1 2 7 A ) . 1984 (pp. 97, 122, 172). 9. Baker BA: The muscle trigger: evidence of 34. Ferner H, Staubesand J: Sobotta Atlas of Human overload injury. J Neurol Orthop Med Surg 7 : 3 5 - Anatomy, Ed. 10, Vol. 2. Urban & Schwarzen- 44, 1986. 1 0 . Bardeen CR: T h e musculature, Sect. 5. In Mor- berg, Baltimore, 1983 (Figs. 331, 403, 406). ris's Human Anatomy, edited by C. M. Jackson, 35. Ibid. (Fig. 4 0 4 ) . Ed. 6. Blakiston's Son & Co., Philadelphia, 36. Ibid. (Fig. 4 1 9 ) . 1921 (p. 493). 37. Ibid. (Fig. 4 2 0 ) . 11. Barton PM, Grainger RW, Nicholson RL, et al.: 38. Ibid. (Fig. 4 2 1 ) . Toward a rational management of piriformis syndrome. Arch Phys Med Rehabil 69:784, 1 9 8 8 . 39. Fishman LM: Electrophysiological evidence of 12. Basmajian JV, Deluca CJ: Muscles Alive, Ed. 5. piriformis syndrome—II. Arch Phys Med Rehabil Williams & Wilkins, Baltimore, 1985 (p. 319). 69:800, 1988. 13. Beaton LE, Anson BJ: The relation of the sciatic 40. Freiberg AH, Vinke TH: Sciatica and the sacro- nerve and its subdivisions to the piriformis iliac joint. J Bone Joint Surg 16[Am]:\\26-36, muscle. Anat Rec 70 ( S u p p l . ) : l - 5 , 1937. 1934. 14. Beaton LE, Anson BJ: The sciatic nerve and the piriformis muscle: their interrelationship a 41. Freiberg AH: Sciatic pain and its relief by oper- possible cause of coccygodynia. J Bone Joint ations on muscle and fascia. Arch Surg 3 4 : 3 3 7 - Surg [Br] 2 0 : 6 8 6 - 6 8 8 , 1 9 3 8 . 350, 1937. 15. Brown JA, Braun MA, Namey TC: Pyriformis syndrome in a 10-year-old boy as a complica- 42. Freiberg AH: The fascial elements in associ- tion of operation with the patient in the sitting ated low-back and sciatic pain. J Bone Joint position. Neurosurgery 2 3 : 1 1 7 - 1 1 9 , 1 9 8 8 . Surg [Am]23A7S-A80, 1941. 16. Cailliet R: Low Back Pain Syndrome. Ed. 3. F.A. 43. Hallin RP: Sciatic pain and the piriformis mus- Davis, Philadelphia, 1981 (pp. 192-194). cle. Postgrad Med 7 4 : 6 9 - 7 2 , 1983. 17. Cameron HU, Noftal F: The piriformis syn- 44. Hinks AH: Letters: Further aid for piriformis drome. Can J Surg 37:210, 1 9 8 8 . muscle syndrome. J Am Osteopath Assoc 74:93, 18. Carter BL, Morehead J, Wolpert SM, et al.: 1974. Cross-Sectional Anatomy. Appleton-Century- 4 5 . Hollinshead WH: Functional Anatomy of the Crofts, New York, 1977 (Sects. 38, 39, 44, 45). Limbs and Back, Ed. 4. W.B. Saunders, Philadel- 1 9 . Clemente CD: Gray's Anatomy of the Human Body, American Ed. 30. Lea & Febiger, Phila- phia, 1976 (pp. 299-301). delphia, 1985 (pp. 568-571). 46. Hollinshead WH: Anatomy for Surgeons, Vol. 3, 2 0 . Ibid. (Figs. 5 - 2 9 and 5 - 3 0 , pp. 3 6 1 - 3 6 3 ) . The Back and Limbs, Ed. 3. Harper & Row, New 2 1 . Ibid. (Fig. 6 - 7 4 , p. 5 6 9 ) . 2 2 . Ibid. (p. 5 7 0 ) . York, 1982 (pp. 666-668, 702) 2 3 . Ibid. (p. 5 7 1 , Fig. 6 - 7 5 ) . 24. Ibid. (pp. 1 2 3 0 - 1 2 3 1 ) . 47. Jan M-H, Lin Y-F: Clinical experience of apply- 2 5 . Ibid. (p. 1 2 3 6 ) . 2 6 . Ibid. (p. 1 2 4 4 ) . ing shortwave diathermy over the piriformis 27. Cohen BA, Lanzieri CF, Mendelson DS, et al: for sciatic patients. Taiwan I Asueh Hui Tsa Chih 82:1065-1070, 1983. CT evaluation of the greater sciatic foramen in 4 8 . Julsrud ME: Piriformis syndrome. J Am Podiatr patients with sciatica. AJNR 7 : 3 3 7 - 3 4 2 , 1986. Med Assoc 7 9 : 1 2 8 - 1 3 1 , 1989. 28. De Luca CJ, Bloom LJ, Gilmore LD: Compres- 49. Karl RD, Jr., Yedinak MA, Hartshorne MF, sion induced damage on in-situ severed and intact nerves. Orthopedics 7 0 : 7 7 7 - 7 8 4 , 1987. Cawthon MA, Bauman JM, Howard WH, 2 9 . Duchenne G B : Physiology of Motion, translated Bunker SR: Scintigraphic appearance of the by E.B. Kaplan. J.B. Lippincott, Philadelphia, piriformis muscle syndrome. Clin Nucl Med 10: 1949 (255, 256). 361-363, 1985. 50. Kipervas IP, Ivanov LA, Urikh EA, Pakhomov SK: [Clinico-electromyographic characteristics of piriformis muscle syndrome) (Russian) Zh Nevropatol Psikhiatr 7 6 : 1 2 8 9 - 1 2 9 2 , 1 9 7 6 . 51. Kirkaldy-Willis WH, Hill RJ: A more precise diagnosis for low-back pain. Spine 4 : 1 0 2 - 1 0 9 , 1979. 52. Lee C-S, Tsai T-L: The relation of the sciatic nerve to the piriformis muscle. J Formosan Med ASSOC 7 3 : 7 5 - 8 0 , 1 9 7 4 . 53. Lewit K: Manipulative Therapy in Rehabilitation of the Motor System. Butterworths, London, 1985, (pp. 278, 279).

Chapter 10 / Piriformis and Other Short Lateral Rotators 213 54. Lewit K: Postisometric relaxation in combina- 79. Reichel G, Gaerisch F Jr: Ein Beitrag zur Differ- tion with other methods of muscular facilita- entialdiagnose von Lumbago und Kokzygo- tion and inhibition. Manual Med 7 : 1 0 1 - 1 0 4 , dynie. Zent bl Neurochir 4 9 : 1 7 8 - 1 8 4 , 1 9 8 8 . 1986. 80. Retzlaff EW, Berry AH, Haight AS, Parente PA, Lichty HA, et al. The piriformis muscle syn- 55. Lewit K, Simons DG: Myofascial pain: relief by drome. J Am Osteopath Assoc 7 3 : 7 9 9 - 8 0 7 , 1 9 7 4 . post-isometric relaxation. Arch Phys Med Re- habil 6 5 : 4 5 2 - 4 5 6 , 1984. 81. Rodnan GP: Primer on the Rheumatic Diseases. 56. Long C: Myofascial pain syndromes: Part III— Arthritis Foundation, 1983 (pp. 87, 179, 181). some syndromes of trunk and thigh. Henry Ford 82. Rohen JW, Yokochi C: Color Atlas of Anatomy, Hospital Bulletin 3 : 1 0 2 - 1 0 6 , 1955 (p. 104). Ed. 2. Igaku-Shoin, New York, 1988 (pp. 418, 57. McMinn RMH, Hutchings RT: Color Atlas of Human Anatomy. Year Book Medical Publishers, 419). 8 3 . Ibid. (p. 441). Chicago, 1977 (p. 81). 84. Saudek CE: The hip, Chapter 17. In Orthopaedic 58. Ibid. (p. 245). 59. Ibid. (p. 264). and Sports Physical Therapy, edited by J.A. 60. Ibid. (pp. 273, 274). 61. Ibid. (p. 293). Gould III and G.J. Davies, Vol. 2. CV Mosby, St. 62. Mirman MJ: Sciatic pain: two more tips. Post- Louis, 1985 (pp. 365-407, see Figs. 17-31, 1 7 - grad Med 74:50, 1983. 63. Mitchell FL: Structural pelvic function. Acad- 42, 17-43). 85. Sheon RP, Moskowitz RW, Goldberg VM: Soft emy of Applied Osteopathy Yearbook 2 : 1 7 8 - 1 9 9 , Tissue Rheumatic Pain, Ed. 2. Lea & Febiger, 1965. Philadelphia, 1987 (pp. 168-169). 64. Mizuguchi T: Division of the pyriformis mus- cle for the treatment of sciatica. Arch Surg 111: 86. Shordania JF: Die chronischer Entziindung des 719-722, 1976. Musculus piriformis—die piriformitis—als 65. Miiller A: Piriformitis? Die Medizinische Welt 24: eine der Ursachen von Kreuzschmerzen bei 1037, 1937. Frauen. Die Medizinische Welt 7 0 : 9 9 9 - 1 0 0 1 , 66. Myint K: Nerve compression due to an abnor- 1936. mal muscle. Med J Malaysia 3 6 : 2 2 7 - 2 2 9 , 1 9 8 1 . 87. Simons, DG: Myofascial pain syndromes, part 67. Nainzadeh N, Lane ME: Somatosensory evoked of Chapter 11. In Medical Rehabilitation, edited potentials following pudendal nerve stimula- by J.V. Basmajian and R.L. Kirby. Williams & tion as indicators of low sacral root involve- Wilkins, Baltimore, 1984 (pp. 209-215, 3 1 3 - ment in a postlaminectomy patient. Arch Phys Med Rehabil 6 8 : 1 7 0 - 1 7 2 , 1987. 320). 68. Namey TC, An HS: Emergency diagnosis and 88. Simons DG: Myofascial pain syndrome due to trigger points, Chapter 4 5 . In Rehabilitation Med- management of sciatica: differentiating the icine, edited by Joseph Goodgold. C.V. Mosby non-diskogenic causes. Emergency Med Reports Co., St. Louis, 1988 (pp. 6 8 6 - 7 2 3 , see 709, 6:101-109, 1985. 711). 69. Pace JB: Commonly overlooked pain syn- dromes responsive to simple therapy. Postgrad 89. Simons DG, Travell JG: Myofascial origins of Med 5 8 : 1 0 7 - 1 1 3 , 1 9 7 5 . low back pain. 3. Pelvic and lower extremity 70. Pace JB, Henning C: Episacroiliac lipoma. Am muscles. Postgrad Med 7 3 : 9 9 - 1 0 8 , 1 9 8 3 . Fam Physician 6 : 7 0 - 7 3 , 1972. 90. Simons DG, Travell JG: Myofascial pain syn- 71. Pace JB, Nagle D: Piriform syndrome. West J dromes, Chapter 25. In Textbook of Pain, edited Med 724:435^439, 1976. by P.D. Wall and R. Melzack, Ed 2. Churchill 72. Pecina M: Contribution to the etiological ex- planation of the piriformis syndrome. Acta Anat Livingstone, London, 1989 (pp. 364, 365, 377). 705:181-187, 1979. 9 1 . Simons DG, Travell JG, Simons LS: Protecting 73. Pernkopf E: Atlas of Topographical and Applied the ozone layer. Arch Phys Med Rehabil 77:64, Human Anatomy, Vol. 2. W.B. Saunders, Phila- 1990. delphia, 1964 (Fig. 314). 92. Sinaki M, Merritt JL, Stillwell GK: Tension my- 74. Pope MH, Frymoyer JW, Anderson G (eds): Oc- algia of the pelvic floor. Mayo Clin Proc 5 2 : 7 1 7 - cupational Low Back Pain. Praegar, New York, 722, 1977. 1984. 93. Solheim LF, Siewers P, Paus B: The piriformis muscle syndrome. Acta Orthop Scand 5 2 : 7 3 - 7 5 , 75. Popelianskii la. Iu., Bobrovnikova TI: [The syn- 1981. drome of the piriformis muscle and lumbar discogenic radiculitis.) (Russian) Zh Nevropatol 94. Stein JM, Warfield CA: Two entrapment neu- Psikhiatr 6 8 : 6 5 6 - 6 6 2 , 1968. ropathies. Hosp Pracf:100A-100P, January 76. Porterfield JA: The sacroiliac joint, Chapter 23. 1983. In Orthopaedic and Sports Physical Therapy, ed- 95. Steiner C, Staubs C, Ganon M, et al.: Piriformis ited by J.A. Gould and G.J. Davis. The C.V. syndrome: pathogenesis, diagnosis and treat- ment. J Am Osteopath Assoc 8 7 : 3 1 8 - 3 2 3 , 1 9 8 7 Mosby Co., St. Louis, 1985 (pp. 550-580, see (p. 322, Fig. 3). 553, 565-566). 96. Stimson BB: The low back problem. Psychosom 77. Rasch PJ, Burke RK: Kinesiology and Applied Med 9 : 2 1 0 - 2 1 2 , 1947. Anatomy, Ed. 6. Lea & Febiger, Philadelphia, 97. Synek VM: Short latency somatosensory 1978 (p. 278). evoked potentials in patients with painful 78. Rask MR: Superior gluteal nerve entrapment dysaesthesias in peripheral nerve lesions. Pain syndrome. Muscle Nerve 3 : 3 0 4 - 3 0 7 , 1980. 29:49-58, 1987. 98. Synek VM: The piriformis syndrome: review and case presentation. Clin Exper Neurol 2 3 : 3 1 - 37, 1987.

214 Part 1 / Lower Torso Pain 99.  TePoorten  BA:  The  piriformis  muscle.  J Am Osteopath 105. Travell  W,  Travell  J:  Technique  for  reduction  and  ASSOC 69:150‐160, 1969.  ambulatory  treatment  of  sacroiliac  displacement.  Arch Phys Ther 23:222‐232, 1942.  100. Thiele  GH:  Coccygodynia  and  pain  in  the  superior  gluteal region. JAMA 709:1271‐1275, 1937.  106. Travell  J,  Travell  W:  Therapy  of  low  back  pain  by  manipulation  and  of  referred  pain  in  the  lower  101. Tillmann  VB:  Variation  in  the  pathway  of  the  extremity  by  procaine  infiltration.  Arch Phys Ther inferior gluteal nerve. Anat Anz 745:293‐302, 1979.  27:537‐547, 1946.  102. Toldt  C:  An Atlas of Human Anatomy, translated  by  107. Voss  DE,  Ionta  MK,  Myers  BJ:  Proprioceptive M.E.  Paul,  Ed.  2,  Vol.  1.  Macmillan,  New  York,  1919  Neuromuscular Facilitation, Ed.3.  Harper  &  Row,  (p. 341).  Philadelphia, 1985 (pp. 304‐305).  103. Ibid. (pp. 346, 347).  108. Wood J: On  some varieties in  human myology.  Proc 104. Travell  JG,  Simons  DG:  Myofascial Pain and Dys- R Soc Lond 73:299‐303, 1894.  function: The Trigger Point Manual. Williams  &  109. Wyant  GM:  Chronic  pain  syndromes  and  their  Wilkins, Baltimore, 1983 (pp. 74‐86, 86‐87, 364‐365).  treatment.  III.  The  piriformis  syndrome.  Can Anaesth Soc J 26:305‐308, 1979.   

PART 2 CHAPTER 11 Hip, Thigh, and Knee Pain-and-Muscle Guide INTRODUCTION TO PART 2 the pectineus, the tensor fasciae latae, sarto- rius, and popliteus muscles. Differential diagno- This second part of THE TRIGGER POINT sis of an individual muscle's referred pain pat- MANUAL includes all of the thigh muscles not tern is considered under Section 6, Symptoms, included in Part 1 of Volume 2: the quadriceps in each muscle chapter. femoris, the hamstrings, all adductors including PAIN GUIDE TO INVOLVED MUSCLES a spillover pattern to that pain area. TrP means trigger point. This guide lists the muscles that may be responsible for referred pain in each of PAIN GUIDE the areas shown in Figure 11.1. These ar- eas, which identify where patients may ANTERIOR KNEE PAIN complain of pain, are listed alphabeti- cally below. The muscles most likely to Rectus femoris (14.1, p. 250) refer pain to a designated area are listed Vastus medialis )14.2A and 14.2B, p. 251) under the name of that area. One uses this Adductors longus and brevis (15.1, p. 291) chart by locating the name of the area that hurts and then by looking under that ANTERIOR THIGH PAIN heading for the muscles that are likely to cause the pain. Then, reference should be Adductors longus and brevis (15.1, p. 291) made to the pain patterns of individual Iliopsoas (5.1, p. 90) muscles; the figure and page numbers of Adductor magnus (15.2A, p. 292) each pattern follow in parentheses. Vastus intermedius (14.3, p. 252) Pectineus (13.1, p. 237) In a general way, the muscle listings Sartorius (12.6, p. 227) follow the order of frequency in which Quadratus lumborum (4.1A, p. 30) they are likely to cause pain in that area. Rectus femoris (14.1, p. 250) This order is only an approximation; the selection process by which patients ANTEROMEDIAL KNEE PAIN reach an examiner greatly influences which of their muscles are most likely to Vastus medialis (14.2, p. 251) be symptomatic. Bold face type indi- Gracilis (15.3, p. 293) cates that the muscle refers an essential Rectus femoris (14.1, p. 250) pain pattern to that pain area. Normal Sartorius, lower TrP (12.6, p. 227) type indicates that the muscle may refer Adductors longus and brevis (15.1, p. 291) 215

216 Part 2 / Hip, Thigh, and Knee Pain Lateral thigh and hip pain Lateral thigh and hip pain Anterior thigh pain Posterior thigh pain Medial thigh pain Medial thigh pain Anterior knee pain Posterior knee pain Lateral knee pain Lateral knee pain Anteromedial knee pain Rear view Front view Figure 11.1. Designated areas (red) in the hip, thigh, nated area from the muscles listed in the PAIN GUIDE and knee regions where patients may describe myo- on the previous page and on this page. fascial pain. The pain may be referred to each desig- LATERAL KNEE PAIN Sartorius (12.6, p. 227) Vastus lateralis (14.4 TrP1-4, p. 253) POSTERIOR KNEE PAIN LATERAL THIGH AND HIP PAIN Gastrocnemius (21.1 TrP3 TrP4, p. 399) Biceps femoris (16.1, p. 317) Gluteus minimus (9.2, p. 169) Popliteus (17.1, p. 340) Vastus lateralis (14.4 T r P 2 5 , p. 253) Semitendinosus and semimembranosus (16.1, Piriformis (10.1, p. 188) Quadratus lumborum (4.14, p. 30) p. 317) Tensor fasciae latae (12.1, p. 218) Gastrocnemius (21.1 TrP1 p. 399) Vastus intermedius (14.3, p. 252) Soleus (22.1 TrP2, p. 429) Gluteus maximus (7.1B, TrP2, p. 133) Plantaris (22.3, p. 430) Vastus lateralis (14.4 TrP1 p. 253) Rectus femoris (14.1, p. 250) POSTERIOR THIGH PAIN MEDIAL THIGH PAIN Gluteus Minimus (9.1, p. 169) Semitendinosus and semimembranosus Pectineus (13.1, p. 237) Vastus medialis (14.2B, p. 251) (16.1A, p. 317) Gracilis (15.3, p. 293) Biceps femoris (16.1, p. 317) Adductor magnus (15.2A, TrP1 p. 292) Piriformis (10.1, p. 188) Obturator internus (6.1B, p. 112)

CHAPTER 12 Tensor Fasciae Latae Muscle and Sartorius Muscle \"Pseudotrochanteric Bursitis\" and \"Surreptitious Accomplice\" HIGHLIGHTS—TENSOR FASCIAE LATAE: RE- palpation with the patient supine. Frequently, a FERRED PAIN and tenderness from trigger local twitch response is evident. ASSOCIATED points (TrPs) in the tensor fasciae latae muscle TRIGGER POINTS seen with tensor fasciae concentrate in the anterolateral thigh over the latae TrPs most often are in the anterior gluteus greater trochanter and extend down the thigh to- minimus muscle, sometimes in the rectus ward the knee. Proximal ANATOMICAL AT- femoris, iliopsoas, or sartorius muscles. INTER- TACHMENTS of the tensor fasciae latae are to MITTENT COLD WITH STRETCH for inactivat- the anterior iliac crest and anterior superior iliac ing TrPs in the tensor fasciae latae is most ef- spine. Distally, the anteromedial tendinous fi- fectively done with the side-lying patient posi- bers of the tensor fasciae latae terminate in the tioned so that, as the vapocoolant or ice is lateral patellar retinaculum and in the deep fas- applied distalward over the muscle and antero- cia of the leg superficial to the patellar ligament. lateral thigh, the thigh is first extended. Gravity The posterolateral half of the muscle's tendon is then allowed to pull the thigh into adduction attaches below the knee onto the lateral tubercle and lateral rotation. Application of a moist heat- of the tibia via the iliotibial tract, from which ing pad and slow active range of motion com- some fibers branch to the lateral femoral con- plete the procedure. INJECTION of the rela- dyle and the linea aspera of the lower femur. tively superficial TrPs in this muscle involves no FUNCTION of the tensor fasciae latae in normal special caveats or unusual precautions. COR- gait is to assist hip flexion during swing and to RECTIVE ACTIONS include avoiding prolonged assist in stabilization of the pelvis during stance. hip flexion and, as home therapy, the patient is It acts to assist flexion, abduction, and medial taught a hip extension exercise for stretching the rotation of the thigh (in that order of importance), tensor fasciae latae and other hip flexor mus- and to help stabilize the knee. All fibers of the cles. muscle may assist flexion and abduction of the thigh. The most anteromedial fibers are always HIGHLIGHTS—SARTORIUS: REFERRED PAIN involved in flexion and abduction of the thigh. from trigger points (TrPs) in the sartorius muscle The most posterolateral fibers always assist me- is often described as sharp or tingling, not the dial rotation of the thigh and stabilization of the deep ache that usually characterizes myofascial knee. SYMPTOMS include pain deep in the hip TrP pain. The disturbing sensation appears in and down the thigh as far as the knee. The pain the general vicinity of the TrP. Proximal ANA- prevents walking rapidly or lying comfortably on TOMICAL ATTACHMENTS of the sartorius the side of the TrPs. Pain referred from this muscle are to the anterior superior iliac spine, muscle mimics pain from TrPs in the anterior and distal attachments are to the medial surface gluteus minimus, gluteus medius, and vastus of the upper tibia. The muscle curves diagonally lateralis muscles, and also is often mistakenly across the front of the thigh. FUNCTION of the attributed to trochanteric bursitis. PATIENT EX- sartorius includes assisting hip flexion and knee AMINATION reveals restriction of extension at flexion during walking. It assists flexion, abduc- the hip and limited adduction (Ober sign). TRIG- tion, and lateral rotation of the thigh, in that order GER POINT EXAMINATION is conducted by flat of importance. TRIGGER POINT EXAMINA- 217

218 Part 2 / Hip, Thigh, and Knee Pain TION is p e r f o r m e d b y flat p a l p a t i o n of t h e m u s - n i q u e s or INJECTION, w h i c h is u s u a l l y u n - cle with the patient supine. Meralgia paresthet- complicated for the TrPs in this superficial i c a is u s u a l l y c a u s e d b y ENTRAPMENT of t h e lateral femoral cutaneous nerve as it exits the m u s c l e . CORRECTIVE ACTIONS primarily pelvis at the inguinal ligament. For this muscle, consist of avoidance of strain of the sartorius INTERMITTENT COLD WITH STRETCH is (e.g., avoid sitting in the lotus position) and avoidance of prolonged hip flexion during the usually less satisfactory than massage tech- day or at night. 1. REFERRED PAIN—TENSOR FASCIAE pain to the thigh,45,57,104 along the outside of the LATAE (Fig. 12.1) thigh, knee, and calf,55 and into the hip and anter- The term \"pseudotrochanteric bursitis\" applies to the pain and tenderness re- olateral aspect of the thigh.95-97 Arcangeli et al.9 il- ferred from trigger points (TrPs) in the tensor fasciae latae muscle. Patients with lustrated pain referred from TrPs in the tensor fas- these TrPs often describe pain in the hip joint region and down the anterolateral ciae latae muscle that projected to the anterolat- aspect of the thigh (Fig. 12.1), occasion- ally extending as far as the knee. The pain eral portion of the thigh. Kellgren56 induced pain is more severe during movement of the hip. These patients are likely to be mis- referred over the lateral surface of the buttock, diagnosed as having trochanteric bursitis. thigh, knee, and upper half of the anterolateral leg Other authors have identified myalgic spots (TrPs) localized in the tensor fasciae latae mus- by injecting hypertonic saline into the tensor fas- c l e . 4 1 , 4 2 , 4 5 When compressed, these TrPs referred ciae latae muscle. Figure 1 2 . 1 . Pattern of pain (bright red) referred from a trigger point (X) in the right tensor fasciae latae 2. ANATOMICAL ATTACHMENTS AND muscle (red), fascia removed. CONSIDERATIONS—TENSOR FASCIAE LATAE (Fig. 12.2) The tensor fasciae latae muscle attaches proximally to the anterior part of the outer lip of the crest of the ilium, to the outer aspect of the anterior superior iliac spine (Fig. 12.2), and to the deep surface of the fascia lata.23 At its upper anterior attachment, it lies between the gluteus medius and the sartorius. Distally, the anteromedial part and the posterolateral part of the muscle form different attach- ments, which are reflected in equally dis- tinctive functions.85 (In other mammals, including other primates, the iliotibial tract and the fascia lata are separate struc- tures with different functions.85) The tendinous fibers of the anter- omedial half of the tensor fasciae latae muscle extend down the thigh and curve anteriorly at the level of the patella to in- terweave with the lateral patellar retinac- ulum and the deep fascia of the leg super- ficial to the patellar ligament. Contrary to earlier, less detailed studies, tendinous fi- bers of this anteromedial half of the mus- cle do not attach directly to the patella; most are secured at or above the knee.85 The tendinous fibers of the postero- lateral half of the tensor fasciae latae muscle join the fibers of the longitudinal middle layer of the fascia lata (iliotibial

Chapter 12 / Tensor Fasciae Latae and Sartorius Muscle 219 Upper border of Anterior superior gluteus maximus muscle iliac spine Greater trochanter Iliotibial tract Fibula Patella Lateral patellar retinaculum Lateral tibial tubercle Figure 12.2. Side view of attachments of the right Below, the anteromedial tendinous fibers attach to the tensor fasciae latae muscle (red, fascia cut). Above, fascia at the knee, and the posterolateral tendinous fi- the muscle attaches along and below the crest of the bers anchor to the iliotibial tract, which continues down ilium just posterior to the anterior superior iliac spine. to the lateral tubercle of the tibia. tract). This fibrous band attaches dis- The tensor fasciae latae is a relatively tally to the lateral tubercle of the tibia, small postural muscle. It is about half the but some fibers from its deep surface weight of the gluteus minimus and one- branch off and attach to the lateral femo- fourth the weight of the gluteus medius.48 ral condyle and linea aspera of the fe- mur. Traction on this band (the middle Variations in this muscle include an accessory layer of the fascia lata) produced tension slip to the inguinal ligament. Sometimes its fibers in the iliotibial tract that was visible all fuse with those of the gluteus maximus to form a the way down to the lateral tubercle of muscular mass comparable to the deltoid muscle the tibia. However, some of the force of the shoulder.\" The tensor fasciae latae has been was taken up by the fascial attachments reported to be congenitally absent as a family to the femur.85 trait.70 Tendinous fibers of the superior por- Supplemental References tion of the gluteus maximus muscle also join the iliotibial tract via the superficial The tensor fasciae latae is shown from in front,36,76 layer of oblique interweaving fibers.85 in dissection,89 from in front with vessels and

220 Part 2 / Hip, Thigh, and Knee Pain nerves,92 and in relation to the gluteus minimus.80 hip. The posterolateral fibers were always in- It is seen from behind in dissection90 and in rela- volved in medial rotation, but the anteromedial fi- tion to the gluteus minimus,81 and from the lateral bers were active during medial rotation only side in its entirety.34 The muscle appears in a full when the hip was also flexed, or abducted 45°. As series of cross sections,20 in three cross sections of expected, the muscle did not contribute to lateral the thigh,79 and at one level.36 Photographs reveal rotation.85 Understandably, the findings of previ- its surface contours through the skin.2, 35, 65 Its bony ous authors, who made no distinction between attachment is marked on the anterior iliac these two groups of fibers, were frequently contro- crest.37,78 versial. 3. INNERVATION—TENSOR FASCIAE Stimulation of the tensor fasciae latae muscle LATAE produced strong medial rotation and some flexion of the thigh,29,53 but weak53 or no29 abduction. A branch of the superior gluteal nerve to However, Merchant,71 using a mechanical model, the gluteus minimus muscle innervates concluded that the tensor fasciae latae contributed the tensor fasciae latae muscle. The nearly one-third of the abductor force at the hip nerve derives its fibers from the fourth with the pelvis and femur in neutral position, and and fifth lumbar and the first sacral spi- that this force was markedly increased by lateral nal nerves.23 rotation and markedly decreased by medial rota- tion of the femur. 4. FUNCTION—TENSOR FASCIAE Functions LATAE Pare and associates85 have shown that the As is the case for most other lower limb anteromedial half and the posterolateral muscles, the tensor fasciae latae functions half of the tensor fasciae latae muscle are during the stance phase of gait primarily active at different times for different rea- to control m o v e m e n t (often at a proximal sons. During walking, the most anter- segment) rather than to produce it. This omedial fibers were activated in the muscle assists the gluteus medius and swing limb (during midswing); the most gluteus minimus in stabilizing the pelvis posterolateral fibers were activated in the (countering the tendency to fall away stance limb. The posterolateral fibers are from the support limb).86 The most pos- also active at heel-strike during jogging, terolateral fibers also are involved in sta- running, or sprinting,68,85 stepping up on a bilizing the knee.85 platform, and climbing a ladder. The more vigorous the activity, the more vig- Actions orous were these responses. The fact that the anteromedial portion of the muscle at- In general, the tensor fasciae latae assists taches at and above the knee and that the flexion, abduction, and medial rotation of posterolateral portion also attaches below the thigh at the hip.14,87 the knee fits with the cited E M G evidence that the anteromedial portion of the mus- More specifically, electromyographic (EMG) cle acts primarily as a flexor of the thigh findings indicate that all fibers, at times, may as- while the posterolateral portion acts more sist flexion and abduction of the thigh. Only the as a stabilizer of the knee. anteromedial fibers, however, are always involved in flexion and abduction of the thigh. Only the In an EMG study of selected sports skills,17 both most posterolateral fibers are always active in me- the right and left tensor fasciae latae muscles were dial rotation; they are also involved in locking the vigorously active during volleyball and basketball knee in full extension with the hip maintained in jumping activities. Both muscles were slightly to medial rotation.85 moderately active during right-handed throwing activities, during a tennis serve, and when batting This muscle is a flexor of the thigh at the hip a baseball. regardless of what the knee is doing.14,38 The pos- terolateral fibers were active electromyographi- Lifting a heavy load from the floor caused mini- cally during flexion of the thigh only when it was mal EMG activity in the tensor fasciae latae mus- also rotated medially. These posterolateral fibers cle, but a step forward while holding the load were active during abduction of the thigh except evoked nearly 50% of the maximum voluntary when it was combined with lateral rotation of the

Chapter 12 / Tensor Fasciae Latae and Sartorius Muscle 221 level of activity,74 consistent with the results ob- arising from TrPs in the anterior gluteus served by Pare and associates.85 During bicy- minimus, gluteus medius, or vastus later- cling,47 this muscle was active electromyographi- alis muscles. Certain TrPs in the quad- cally during the period when the hip flexors be- ratus lumborum muscle also refer pain came active as the pedal progressed upward from and tenderness to the greater trochanter. horizontal through the top of its stroke. An L4 neuropathy caused by lumbar Absence53 or paralysis72 of the tensor fasciae spine derangement, or the peripheral latae produced no changes in gait or in function at nerve entrapment of meralgia paresthet- the knees or hips. However, stress testing was not ica, may produce pain distribution con- reported. fusingly similar to the pattern of pain re- ferred from tensor fasciae latae TrPs. Sec- 5. FUNCTIONAL (MYOTATIC) U N I T - tion 10A, which follows in this chapter, TENSOR FASCIAE LATAE discusses meralgia paresthetica in detail. When patients have symptoms of mer- For flexion of the thigh, the tensor fasciae algia paresthetica, they may, in addition, latae muscle works with the following ag- have active TrPs in the tensor fasciae onists: the rectus femoris, iliopsoas, pec- latae muscle that are also contributing to tineus, anterior gluteus medius and mini- their symptoms. mus, and sartorius muscles. Its chief an- tagonists for this function are the gluteus Patients with tensor fasciae latae TrPs maximus and hamstring muscles. are readily misdiagnosed as having tro- chanteric bursitis. These patients with For abduction of the thigh, the agonists TrPs do have pain and tenderness over are the gluteus medius and gluteus mini- the bursa, but these symptoms are re- mus. This function is opposed by the ad- ferred from the TrPs and are not caused ductor group of hip muscles and the by disease of the bursa. gracilis.87 The iliotibial tract friction syndrome 6. SYMPTOMS—TENSOR FASCIAE causes diffuse pain and tenderness of the LATAE lateral femoral condyle where the ilio- tibial tract rubs back and forth; this condi- Patients with active TrPs in the tensor fas- tion is common in bowlegged runners ciae latae muscle are aware primarily of with pronated feet and is seen in those the referred pain, usually in the hip joint, who wear shoes with worn lateral soles.18 and of pain and soreness (referred tender- ness) in the region of the greater trochan- Sacroiliitis (sacroiliac arthritis) refers ter. Some complain of pain extending pain and tenderness to the low back, but- down the thigh as far as the knee. They tock, and, like tensor fasciae latae TrPs, to have poor tolerance for prolonged sitting the lateral thigh. However, the pain of with the hip flexed 90° or more (jack- sacroiliitis may extend beyond the knee knifed position). Pain prevents them from to the ankle.73 walking rapidly. 7. ACTIVATION AND PERPETUATION These patients are usually unable to lie OF TRIGGER POINTS—TENSOR comfortably on the side of the TrPs be- FASCIAE LATAE cause doing so puts body-weight pressure on the area of referred tenderness over the Activation of tensor fasciae latae TrPs greater trochanter and directly on the may be due to sudden trauma, as when TrPs. They are sometimes unable to lie on landing on the feet from a high jump, or the opposite side without a pillow be- to chronic overload. This chronic over- tween the knees because of the tight ilio- load may be caused by jogging uphill and tibial band. Until these patients discover downhill without appropriate support for the value of this pillow, they often must a foot with a Morton foot structure or sleep on the back. other factor causing an excessively pro- nated foot. Differential Diagnosis Regular walking or running on surfaces Pain referred from TrPs in the tensor fas- that are sloped to one side can lead to ten- ciae latae can easily be mistaken for pain sor fasciae latae problems because these slants increase genu varus in one leg and

222 Part 2 / Hip, Thigh, and Knee Pain genu valgus in the other. They also in- ment with the other.61 Loading the muscle crease pronation on one side and limit it during either test is likely to cause pain in on the other. the region of that hip joint if the muscle has active TrPs. Poor conditioning and inadequate warm- up stretching exercises can lead to injuries In a common syndrome of muscle im- that activate or perpetuate TrPs in runners. balance,63 tight tensor fasciae latae and quadratus lumborum muscles overpower As in other muscles, TrPs in the tensor an inhibited or weak gluteus medius fasciae latae are aggravated by immobili- muscle. The patient stands with a for- zation in the shortened position for long ward tilt of the pelvis and accentuated periods. This happens during prolonged lumbar lordosis. Release of TrP tension sitting with the hip at an acute angle or of the tight muscles must precede efforts while sleeping in a tightly flexed fetal po- to strengthen the gluteus medius. sition. A tight tensor fasciae latae and/or a In a study of 100 patients with myofas- tight gluteus maximus muscle can con- cial pain as the result of a first serious au- tribute to iliotibial band tightness. A tight tomobile collision, Baker10 reported the iliotibial band causes the Ober sign;43,83,94 activation of very few tensor fasciae latae with the patient lying on the side oppo- TrPs regardless of the direction of impact. site to the tight band, the knee of the up- permost limb does not reach the table. 8. PATIENT EXAMINATION—TENSOR Tightness of the tensor fasciae latae mus- cle can also produce the appearance of a FASCIAE LATAE shorter limb on the involved side when the patient is examined in the supine or Patients with tensor fasciae latae TrPs prone position, in a manner similar to tend to keep the hip slightly flexed when that illustrated for the quadratus lum- standing and have difficulty leaning back- borum muscle (see Fig. 4.9). See Chapter wards and hyperextending the hip (a 4, Section 8, for details on how to deter- movement that is restricted also by TrPs mine lower limb-length inequality. in the iliopsoas and anterior sections of the gluteus medius and gluteus minimus The region of the greater trochanter muscles). Ambulation with the hips may be tender to palpation because of re- flexed is not painful. Pain on walking that ferred tenderness from TrPs and is not al- is caused by tensor fasciae latae TrPs dis- ways a sign of trochanteric bursitis. appears if the upper limbs carry the body weight (as w h e n using crutches). The authors know of no study that specifically reports the prevalence of latent TrPs in children. The patient may be examined for mus- However, in one study,66115 school children aged cle tightness in the supine position with 8-20 years were examined for muscle tightness one hip held in flexion by the patient and including tightness of the tensor fasciae latae the other limb extended over the end of muscle. The children were examined three times the treatment table, as illustrated in Fig- over a period of 4 years. The results showed a ure 5.3 of the Iliopsoas chapter. In this correlation among increasing height, increasing position, the affected thigh can be tested weight and low physical fitness, and the develop- for restriction of adduction by pressing ment of shortened muscles; it was stronger in boys the thigh of the extended limb medi- than in girls.86 The cause of the muscle tightness ally.51,62 When the tensor fasciae latae was not evaluated. muscle is tight, adduction is limited to a range of less than 15°, and the longitudi- 9. TRIGGER POINT EXAMINATION- nal groove on the lateral aspect of the TENSOR FASCIAE LATAE thigh beside the fascia lata deepens. The (Fig. 12.3) abduction function of this muscle is tested with the patient lying on the side The TrPs in this superficial muscle are opposite to the one being tested; the pa- disclosed in the supine patient by flat pal- tient is asked to raise the foot of the up- pation, as illustrated in Figure 12.3. The permost limb while the clinician palpates muscle can be located by palpating its both the gluteus medius and tensor fas- tension while the patient rotates the thigh ciae latae muscles with one hand and tests for strength by opposing the move-

Chapter 12 / Tensor Fasciae Latae and Sartorius Muscle 223 Figure 12.3. Palpation of trigger points in the right cle marks the greater trochanter. The dotted line iden- tensor fasciae latae muscle (red). The solid circle lo- tifies the inguinal ligament. The thumb presses at the cates the anterior superior iliac spine and the open cir- usual location of trigger points in this muscle. medially against resistance. When the pa- 12. INTERMITTENT COLD WITH tient is fully relaxed and the muscle is placed under slight (stretch) tension, pal- STRETCH—TENSOR FASCIAE LATAE pation at right angles to the direction of the muscle fibers reveals taut bands and (Fig. 12.4) the spot of maximum tenderness (TrP) in each band. Pressure on active tensor fas- The use of ice for applying intermittent ciae latae TrPs sustained for up to 10 cold with stretch is explained on page 9 seconds augments the pain referred from of this volume and the use of vapocoolant them. Snapping palpation of active TrPs with stretch is detailed on pages 6 7 - 7 4 of in this muscle usually elicits a visible lo- Volume l . 1 0 1 Techniques that augment re- cal twitch response. laxation and stretch are reviewed on page 11 of this volume. Full stretch is avoided 10. ENTRAPMENTS—TENSOR FASCIAE in hypermobile patients. Alternative LATAE treatment methods are reviewed on pages 9-11 of this volume. No neurological entrapments are known to be associated with TrPs in this muscle. For application of intermittent cold with stretch to the tensor fasciae latae, the 11. ASSOCIATED TRIGGER P O I N T S - patient lies on the unaffected side (Fig. TENSOR FASCIAE LATAE 12.4). Ice or vapocoolant spray is applied in slow parallel sweeps distalward from The TrPs in the tensor fasciae latae mus- the crest of the ilium over the anterior cle may occur as a single-muscle syn- thigh to just above the knee. Successive drome or, more commonly, may develop sweeps progress laterally to cover the secondary to TrPs in the anterior gluteus muscle. Meanwhile, the thigh of the up- minimus and, sometimes, in the rectus permost limb is extended and afterward femoris, iliopsoas, or sartorius muscles. guided by the operator as the limb is al- Tensor fasciae latae TrPs cannot be elimi- lowed to be pulled into adduction and nated if active TrPs remain in the anterior lateral rotation by gravity. It is important gluteus minimus muscle, which prevent to start with extension. The muscle is its full stretch. tightened when adduction is attempted initially in hip flexion and can snap pain- This muscle's TrPs do not seem to fully across the greater trochanter. In ad- cause associated TrPs in any of the prime dition to guiding and controlling the in- movers of the hip. volved limb, the clinician's hand should be placed so that it stabilizes the patella.

224 Part 2 / Hip, Thigh, and Knee Pain Figure 12.4. Stretch positions and ice or vapocoolant spray pattern (thin ar- rows) for trigger points in the left tensor fasciae latae muscle. To prevent the muscle from painfully impinging on the greater trochanter as the muscle is lengthened, the operator first extends the abducted thigh and then adducts it, intermittently cooling the skin over the muscle and pain reference zone. Throughout, the patient assists in stabi- lizing the lumbar spine and pelvis by holding the knee of the untreated limb down on the examining table. A, The op- erator applies ice or vapocoolant (thin arrows) downward over the muscle and also over the thigh anterolaterally while gently bringing the partly abducted thigh (fully rendered limb) into extension, and then starts to lower the limb gently into adduction (outlined limb), avoiding me- dial rotation of the thigh. B, To obtain full stretch on this muscle, the operator must stabilize the pelvis with one hand to mini- mize movement of the lumbar spine and pelvis while the thigh is moving into ad- duction. The operator's other hand sup- ports the weight of the limb and firmly grasps the patella to stabilize it against the pull of the fascia lata. Concurrent use of augmented postisometric relaxation provides release of muscle tension since the operator has no free hand with which to apply vapocoolant. Intermittent cold can be employed at this stage if the op- erator releases the pelvis to apply the cold and then reestablishes pelvic posi- tioning prior to further release of the muscle. As the muscle releases, the op- erator then takes up slack in the direc- tion of lateral rotation of the thigh by al- lowing the lower leg to drop downward (thick arrow). A two-operator technique is most effec- the stretch. The Lewit technique per- tive. One clinician stabilizes the pelvis; formed by the patient enhances relaxation the other applies the ice or vapocoolant of the muscle. with one hand while stabilizing the pa- tella and moving the involved limb into An alternative to stabilizing the patella extension and then adduction and lateral manually is to use non-irritating tape for rotation with the other. A single operator the stabilization. can stabilize the pelvis with one arm and body weight, while using the other hand Following intermittent cold with to stabilize the patella and to guide the in- stretch, a moist, wet-proof heating pad is volved lower limb into extension and ad- applied over the muscle and its pain ref- duction. In this case, the ice or vapocool- erence zone until the skin is rewarmed. ant must be applied before, not during, The patient then slowly mobilizes the muscle by several cycles of full active range of motion.

Chapter 12 / Tensor Fasciae Latae and Sartorius Muscle 225 Figure 12.5. Injection of a trigger point in the right anterior superior iliac spine. The dotted line identifies tensor fasciae latae muscle (red). This trigger point is the inguinal ligament. The open circle marks the quite superficial so that the needle is at a small acute greater trochanter. angle to the skin surface. The solid circle locates the 13. INJECTION AND S T R E T C H - If the tensor fasciae latae muscle has been accurately identified, no major nerves TENSOR FASCIAE LATAE or vessels lie in the path of the needle, which is angled nearly horizontally to pen- (Fig. 12.5) etrate this subcutaneous muscle. A full description of the procedure for in- Following this procedure, a few sweeps jection and stretch of any muscle appears of ice or vapocoolant are applied in the in Volume 1, pages 74-86.101 manner illustrated in Figure 12.4. Then, the patient should actively move the thigh Myofascial TrPs in the tensor fasciae slowly through the full flexion-extension latae muscle are injected with the pa- range of hip motion. Finally, moist heat is tient lying supine (Fig. 12.5). The mus- applied over the injection site to minimize cle is identified by asking the patient to postinjection soreness. Postinjection sore- turn the kneecap inward (medially ro- ness can be quite annoying to patients for tate the thigh) while the region of the a few days following injection, and may be muscle is palpated. (If the muscle is al- lessened by supplemental vitamin C prior ready sufficiently tense due to its TrPs, to injection and by acetaminophen after- this procedure may not be needed.) To ward, as needed. localize the taut bands, it may be neces- sary to slacken the muscle slightly by The clinician should carefully examine placing a pillow under the knee, thus the anterior gluteus minimus for associ- flexing the hip slightly. When the TrP ated TrPs and should also inactivate them tenderness has been precisely located, at this time, if a satisfactory result is to be pressure is applied with the fingers of expected. one hand to pin down the taut band as the needle is inserted into its TrPs with 14. CORRECTIVE ACTIONS—TENSOR the other hand (Fig. 12.5). A few millili- FASCIAE LATAE ters of 0.5% procaine in isotonic saline are injected into the cluster of TrPs us- In the patient with a chronic myofascial ing a 37mm (11/2-in) needle; each TrP is pain syndrome, it is important to identify identified by a local twitch response of any mechanical factors that are perpetuat- the muscle, or by a pain response (jump ing the tensor fasciae latae TrPs. Systemic sign) of the patient.

226 Part 2 / Hip, Thigh, and Knee Pain perpetuating factors (see Volume 1, Chap- lized in a shortened position for long peri- ter 4 ) 1 0 1 should also be addressed. ods. Corrective Posture and Activities To reduce irritability of tensor fasciae latae TrPs, it is important to avoid walk- For both this muscle and the sartorius, sit- ing or jogging up hills, which requires ting in the cross-legged lotus position for a leaning forward and flexing the hips. It is period of time should be avoided. It is also also important for a runner to avoid shoes important to avoid prolonged flexion of that are excessively worn and to avoid the thigh at the hip caused by such posi- running on surfaces that slope from side tions as sitting in a jackknifed position in a to side. A benefit for the runner's muscles chair, sleeping on the back with a large is to run on a level track, to run on one pillow under the knees, or sleeping in the side of the road in one direction and on fetal position with the hips and knees the same side of the road for the return strongly flexed. During sleep, the hip trip, or to run only on the crown of a traf- should be kept extended beyond 90° of fic-free road. flexion, and preferably close to full exten- sion. Home Therapeutic Program Chairs in which the patient sits for any A self-stretch exercise for the tensor fas- length of time should provide an open an- ciae latae is performed by lying on the gle at the hips. Either the backrest should side opposite the muscle to be stretched, be tilted backward and the patient should extending and laterally rotating the up- lean back against it most of the time, or permost hip, and relaxing to obtain grav- the front of the seat should be sloped ity-assisted adduction. Some people downward. A pad of folded newspaper stretch this muscle in the standing posi- can be placed across the rear of the seat to tion, using body weight shift for stretch. achieve this desired slope. Patients with tensor fasciae latae TrPs should also perform hip extension exer- On long trips in an automobile, cruise cises similar to those recommended in control permits change of position of the Chapter 5 to release the iliopsoas muscle, lower limbs; thus, the driver can avoid and in Chapter 14 for release of the rectus holding the hip flexor muscles immobi- femoris muscle. SARTORIUS 1A. REFERRED PAIN—SARTORIUS thigh from lateral to medial, forming a (Fig. 12.6) roof over the femoral artery, vein, and nerve in Hunter's canal. In the lower part The specific TrPs illustrated (Fig. 12.6) of the thigh, it descends nearly vertically, and their referred pain patterns up and passing over the medial condyle of the fe- down the muscle are examples of what mur. Distally, the sartorius ends in a ten- can occur anywhere in the sartorius. The don that curves obliquely anteriorly to at- TrPs in this muscle produce a surprising tach to the medial surface of the body of burst of superficial sharp or tingling pain, the tibia just anterior to the attachments not the usual deep aching pain referred of the gracilis and semitendinosus ten- from myofascial TrPs. dons.24 Thus, it is the most anterior of the \"pes anserinus\" muscles. 2A. ANATOMICAL ATTACHMENTS AND CONSIDERATIONS—SARTORIUS The sartorius is one of four muscles in (Fig. 12.7) the body with inscriptions that effec- tively shorten the average fiber length. The thin, narrow, ribbonlike sartorius is (The other three muscles are the rectus the longest muscle in the body.24 It at- abdominis, gracilis,27 and semitendino- taches proximally to the anterior superior sus.25) The microscopic inscriptions of iliac spine (Fig. 12.7). The muscle de- the sartorius are not aligned and do not scends obliquely across the front of the form clearly defined bands across the

Chapter 12 / Tensor Fasciae Latae and Sartorius Muscle 227 Upper trigger Middle trigger Lower trigger point point point Figure 12.6. Referred pain patterns (dark red) of trigger points in this long thin muscle are superficial, three trigger points (Xs) at different levels in the right just under the skin. sartorius muscle (light red), anteromedial view. The muscle, as do the inscriptions of the rec- its innervation,75 and in relation to the lateral fem- tus abdominis and semitendinosus.22,25 oral cutaneous nerve.1 The distal part of the mus- Therefore, sartorius myoneural junctions cle is also viewed from behind.77,90 Its distal end is are also exceptional in their distribution shown from the medial view attaching to the throughout the length of the muscle.8,21,27 tibia91 and in relation to the anserine bursa,82 and Weber103 found that, macroscopically, as the muscle appears in the lateral view.34 The the apparent average length of sartorius muscle and its relation to surrounding structures muscle fibers was 43.5 cm (17 in). The are revealed in serial cross sections,19 in cross sec- next longest were the gracilis muscle fi- tions at three levels,79 and at one level.5,36 Its bony bers which averaged 25.5 cm (10 in) in attachments are marked.4,37,78 The surface contours length. produced by this muscle are demonstrated photo- graphically.2,35,65 Anatomical variations of the sartorius include additional attachments to the inguinal ligament, 3A. INNERVATION—SARTORIUS iliopectineal line of the pubis proximally,24 and to the ligament of the patella, tendon of the The sartorius muscle usually is inner- semitendinosus muscle,24 or to the medial con- vated by two branches that separate from dyle of the femur33 distally. This muscle may be the femoral nerve near the origin of the divided longitudinally into two parallel bellies; anterior cutaneous branches. This muscle it may be crossed by a tendinous inscription, or is supplied by fibers of the second and more rarely may have an intermediate length of third lumbar nerves.24 tendon that divides it into upper and lower bel- lies similar to the division of the digastric mus- 4A. FUNCTION—SARTORIUS cle.13 During the swing phase of gait, the sarto- Supplemental References rius assists the iliacus and the tensor fas- ciae latae in hip flexion and assists the The entire sartorius muscle is shown in front view short head of the biceps femoris in knee without nerves or vessels,6,12,76, 89 in relation to the flexion. It may assist the vastus medialis, vessels and nerves in the femoral triangle,192 with gracilis, and semitendinosus in support-

228 Part 2 / Hip, Thigh, and Knee Pain Figure 12.7. Attachments of the right Anterior sartorius muscle (red), viewed from in superior front and somewhat from the medial side. It attaches proximally to the ante- iliac rior superior spine of the ilium and dis- spine tally to the medial aspect of the upper tibia. The muscle lies deep to the layer of Inguinal fascia shown on both sides of it, and as ligament seen in Figure 12.8 with the fascia intact. Fascia cut Sartorius Patella Tendon of gracilis muscle Patellar Medial condyle ligament of tibia Medial patellar Tibia retinaculum ing the knee medially against the lateral highly variable.7,50 It is more likely to as- thrust (valgus thrust) that occurs during sist knee flexion when the hip is also single limb balance.86 flexed.50 The sartorius earned its name as the In an E M G study of selected sports muscle that assists the hip movements skills,17 both the right and left sartorius necessary to assume the position of a muscles were vigorously active during cross-legged tailor (sartor, a tailor). This volleyball and basketball jumping activi- muscle, like the tensor fasciae latae, is a ties. The left sartorius was consistently flexor and abductor of the thigh, but the more active than the right in all right- sartorius rotates the thigh laterally in- handed ball-throwing and batting activi- stead of medially.87 Electromyographi- ties, as well as during a tennis serve. A cally, the sartorius is activated during ef- detailed EMG study52 of a standing two- forts to flex the thigh38,50,99 and to abduct legged jump revealed the sartorius to be it.50,99 This muscle is essentially not acti- vigorously active through both the take- vated during medial rotation of the off phase and the landing phase of the thigh.50,99 During a lateral rotation effort, jump. the sartorius is only slightly and occa- sionally activated,\" except in the usual Sartorius activity during level walk- sitting position, when there is slight to ing peaks in the middle of swing phase moderate activity.50 Activation of this (assisting hip flexion).50 The sartorius is muscle by knee flexion or extension is active as a hip flexor during bicy- cling.47

Chapter 12 / Tensor Fasciae Latae and Sartorius Muscle 229 5A. FUNCTIONAL (MYOTATIC) UNIT— counters this superficial sartorius TrP, the SARTORIUS patient reports a sharp or tingling pain felt diffusely over the adjacent thigh. The sartorius muscle assists the rectus femoris, iliopsoas, pectineus, and tensor The pain from sartorius TrPs referred to fasciae latae muscles in flexing the thigh the knee may also be mistaken for disease at the hip. This function is opposed by of that joint.88 the gluteus maximus and hamstring mus- cles. 7A. ACTIVATION AND PERPETUATION OF TRIGGER POINTS—SARTORIUS For abduction of the thigh, the sartorius assists the gluteus medius, gluteus mini- Sartorius TrPs do not usually occur as a mus, piriformis, and tensor fasciae latae. single-muscle syndrome, but rather occur This action is opposed by the three hip in conjunction with TrP involvement of adductor muscles and the gracilis. related muscles. Sartorius TrPs are usu- ally activated as secondary TrPs by those The lateral rotation effect of the sarto- in other muscles of its functional unit. rius counters the opposing medial rota- Occasionally, these TrPs may be initiated tion function of the tensor fasciae latae. by an acute overload strain in a twisting Otherwise, they act as agonists. fall. 6A. SYMPTOMS—SARTORIUS The TrPs in this muscle are perpetu- ated by a rocking (excessively pronating) The pain referred from lower sartorius foot, characteristic of the Morton foot TrPs may be felt up and down the thigh structure that is described in Chapter 20. and in the knee region medially, but not deep in the knee. 8A. PATIENT EXAMINATION— SARTORIUS In addition to referred pain, patients with upper sartorius TrPs may have Sartorius TrPs are usually discovered af- symptoms of entrapment of the lateral ter TrPs in functionally related muscles femoral cutaneous nerve (see Section have been inactivated. They often are the 10A). In that case, their symptoms of mer- residue left behind after treatment of algia paresthetica include dysesthesia or more obvious TrPs. The TrPs in this long numbness of the anterolateral aspect of slack muscle do not limit movement or the thigh (see Fig. 12.8). cause mechanical dysfunction; range of motion is not restricted. Weakness and Differential Diagnosis pain on loading the sartorius muscle can be tested with the patient in the seated Pain referred over the anteromedial por- position, knee bent 90°, by performing lat- tion of the knee from TrPs in the lower eral rotation of the thigh at the hip against part of the sartorius is confusingly similar resistance, as illustrated by Saudek.93 to the pain referred from TrPs in the vas- tus medialis muscle. However, the pain In a patient with sartorius TrPs, the at- referred from the sartorius is more diffuse tachment area of the sartorius on the tibia and superficial than the pain deep in the is tender because of sustained tension knee joint usually referred from the vas- and tenderness referred to that region. tus medialis. 9A. TRIGGER POINT EXAMINATION— Lange60 warned that the pain caused by SARTORIUS myogelosis [TrPs] in the lower sartorius muscle is easily mistaken for pain The TrPs of the sartorius muscle are very originating in the knee, and he described superficial and easily missed. One must a case report. use flat palpation across the fiber direc- tion, exploring along the length of the We find that patients rarely present muscle, as described and illustrated by with a complaint of pain caused solely by Lange.59 The taut band is usually detected the sartorius muscle. Lange60 made this first and then the exquisite spot tender- same observation. A sartorius TrP can be ness at the TrP. Local twitch responses discovered serendipitously during injec- tion of a vastus medialis TrP deep to the sartorius muscle. When the needle en-

230 Part 2 / Hip, Thigh, and Knee Pain Lateral femoral Iliopsoas Inguinal ligament cutaneous nerve Femoral Posterior Lateral femoral Sartorius vein branch cutaneous nerve Posterior branch Femoral Anterior of lateral femoral artery branch cutaneous nerve Femoral nerve Sensory distribution Cut edge of of nerve, superficial both branches fascia Occasional extension Anterior branch of sensory of lateral femoral distribution cutaneous nerve Figure 12.8. Potential entrapment of the lateral fem- course of the lateral femoral cutaneous nerve. B, oral cutaneous nerve when it passes through the sar- usual sensory distribution of this nerve, dark gray; oc- torius muscle. A, anatomical relations of this unusual casional extension of its distribution, light gray. elicited by snapping palpation at the TrP nal wall muscles above the ligament, or are often visible in this muscle. muscles distal to its lateral portion. He at- tributed this relief to reduction of tension 10A. ENTRAPMENTS—SARTORIUS in the muscles, which reduced fascial (Fig. 12.8) tension on the inguinal ligament. The authors have observed several pa- Since the cause of meralgia paresthetica tients who were relieved of the symptoms is frequently not known, this topic is crit- of meralgia paresthetica by the injection ically examined here in order to better of a tender spot in the musculature distal understand how muscles might contrib- to the anterior superior iliac spine. The ute to the symptoms of the disorder. location of these tender spots was consist- ent with TrPs in the proximal portion of Meralgia Paresthetica the sartorius muscle. Similarly, Teng100 (Fig. 12.8) was able to relieve patients with this dis- order by injecting the iliacus or quadri- Meralgia (painful thigh) describes a pain ceps femoris muscles distal to the medial syndrome without suggesting a cause. portion of the inguinal ligament. No relief Historically, the etiology of this dysfunc- was obtained when he injected abdomi- tion has been enigmatic. A 1977 review31 culled 80 purported causes from previous

Chapter 12 / Tensor Fasciae Latae and Sartorius Muscle 231 literature. The weight of evidence now in- by the marked angulation of the nerve as it dicates that meralgia paresthetica is usu- emerged from the pelvis. He observed that the an- ally caused by entrapment of, or trauma gulation and tension of the nerve were increased to, the lateral femoral cutaneous nerve as by extension of the thigh98 and decreased by thigh it exits the pelvis. The symptoms are flexion. He also noted that the nerve usually ex- burning pain and paresthesias in the dis- ited superficial to the sartorius muscle, but some- tribution of this nerve, which extends times passed through it (Fig. 12.8A). When the down the anterolateral thigh, sometimes nerve passes through or deep to the sartorius mus- to the knee (Fig. 12.8).58 cle where it lies against the ilium, it would be vul- nerable to compression by that muscle.67 (It also Incidence sometimes crosses the crest of the ilium superior and lateral to the anterior superior iliac spine, This entrapment neuropathy is more common where it would be especially vulnerable to tight than is generally appreciated. The reported inci- clothing and impact trauma.) dence is highly variable, however, depending on the investigator. One neurosurgeon100 identified Edelson and Nathan31 examined 110 lateral fem- five patients with this disorder in the 7 years pre- oral cutaneous nerves in 90 adult and 20 fetal ca- ceding 1963. Then he developed the condition davers for enlargement of the nerve at its pelvic himself, and became a student of the syndrome. In exit. In 51% of adult cases and none of the fetal the subsequent 8 years, he diagnosed 297 patients cases, a significant enlargement or pseudogang- as having meralgia paresthetica. If the examiner is lion was present in the area of the nerve where it not specifically looking for meralgia paresthetica, passed under the inguinal ligament to turn it is easily mistaken for radiculopathy. sharply downward onto the thigh. Anatomy In a more recent autopsy study49 of 12 nerves from patients who had had no known disease of The lateral femoral cutaneous nerve arises from the peripheral nerves, five of the 12 showed une- the dorsal portion of the second and third lumbar quivocal pathological changes at or just below the spinal nerves and appears within the pelvic cavity inguinal ligament. Changes included local demye- as it emerges from the lateral border of the psoas lination and Wallerian degeneration, and micro- major muscle (Fig. 12.8A). It proceeds obliquely scopic increase in connective tissue components. across the iliacus muscle toward the anterior su- The presence of polarized internodal swellings perior iliac spine. It exits the pelvis either above, suggested that mechanical factors were responsi- through, or under the inguinal ligament, usually ble. Endoneurial vascular changes also were ob- within 5 cm (2 in) of the anterior superior iliac served that might contribute to nerve damage.49 spine. Thus, the nerve usually passes through the lacuna musculorum with the iliopsoas muscle. These data strongly suggest that subclinical Keegan and Holyoke54 noted in their study of 50 meralgia paresthetica is far more common than cadavers that the nerve usually passed through a has been realized and that many clinical cases tunnel in the inguinal ligament. Teng100 described probably are overlooked. this passage as an \"inguinal foramen.\" The nerve often makes a right-angle turn as it exits the pel- Teng100 reported a series of 84 operations on pa- vis. It then usually passes superficial to the sarto- tients with meralgia paresthetica. In 26 (31%) of rius muscle and then divides at once into anterior the patients, the foramen through which the nerve and posterior branches. These branches continue penetrated the inguinal ligament was constricted deep to the fascia lata for 5-10 cm (2-4 in) down and would not permit the passage of a probe. In 37 the thigh before both anterior and posterior (44%), the nerve appeared to be compressed by branches pierce this fascial layer to become sub- the posterior fibers of the inguinal ligament and/or cutaneous.26,54,100 a tense fascia lata. Twelve (14%) revealed scarring that appeared to constrict the nerve. (In five (6%) The nerve can become entrapped in several lo- of the patients, the lateral femoral cutaneous cations: beside the spinal column, where branches nerve arose either wholly or in part from the fem- from the lumbar nerves join to form the femoral oral nerve, and the entrapment occurred in the re- cutaneous nerve within the belly of the psoas ma- gion of the cribriform fascia.) In none of these pa- jor; within the abdominal cavity by pressure on tients was the nerve found to pass through the sar- the nerve against the pelvis; or where the nerve torius muscle. exits the pelvis. The last is usually the site of trou- ble. A much higher proportion of nerves was found to pass through the inguinal ligament in surgical Stookey98 did a series of dissections of the lat- reports than in cadaver studies. This suggests that eral femoral cutaneous nerve and was impressed the nerve's penetration of the inguinal ligament

232 Part 2 / Hip, Thigh, and Knee Pain predisposes it to the development of meralgia region where the nerve traverses the in- paresthetica severe enough to require surgery. guinal ligament.15, 40, 100 Lewit64 attributes some cases of meralgia Electrodiagnostic evidence of nerve en- paresthetica to entrapment of the nerve by spasm trapment may be obtained by demonstrat- of the iliopsoas muscle in the lacuna mus- ing a slowed sensory conduction velocity culorum, through which they both pass. Elimina- of the nerve in the region of the inguinal tion of the iliopsoas muscle spasm by manipula- ligament.18 The lateral femoral cutaneous tion of the thoracolumbar junction, lumbosacral nerve contains no motor fibers. junction, hip, or coccyx relieved the symptoms of meralgia paresthetica in these cases.64 Treatment As illustrated in Figure 12.8,4, the lateral femo- Most patients with meralgia paresthetica ral cutaneous nerve might be entrapped by the respond to conservative therapy. Teng100 sartorius muscle as the nerve penetrates the mus- injected every one of his 297 patients cle after passing deep to the inguinal ligament. with lidocaine to block the lateral femoral This apparently is a relatively infrequent anatomi- cutaneous nerve at the inguinal ligament, cal variation and has not been reported in surgical and many experienced prolonged relief. procedures for relief of meralgia paresthetica. Effective conservative therapy includes However, Keegan and Holyoke54 noted that the significant weight loss46 (sometimes with sartorius has a medial aponeurotic expansion as little as 5 or 10 lb),39 avoidance of ex- from its tendinous attachment to the anterior su- cessive extension at the hip, avoidance of perior iliac spine; this aponeurosis attaches to the constricting garments around the hips,46 inferior border of the inguinal ligament and could correction of a lower limb-length inequal- depress this ligament when the muscle contracts. ity,1558 injection of the nerve with lido- It is conceivable that TrP tension in the sartorius caine and prednisone at the spinal44 or in- could exert pressure on the nerve in this way. guinal102 level, and inactivation of sarto- rius TrPs. A steroid could alleviate Clinical Findings symptoms by reducing the local tissue re- actions to trauma. If conservative meas- The pain and/or paresthesia over the an- ures fail, surgery may be required.40,100 terolateral thigh reported by patients with meralgia paresthetica is usually increased 11 A. ASSOCIATED TRIGGER POINTS— by standing or walking,40,54,39,98 and by po- SARTORIUS sitions of hip extension.31100 In one case, it was reported after running and then bi- Sartorius TrPs are likely to be observed in cycling when the symptomatic lower conjunction with TrP tension in other limb was 1 cm (1/2 in) longer than the muscles of the functional unit. The up- other.15 Running may have required addi- permost TrPs in the sartorius may de- tional extension at the hip on the side of velop in association with rectus femoris the longer limb. The symptoms are gener- TrPs. Midmuscle and lower sartorius ally relieved by sitting down or otherwise TrPs can appear in association with vas- flexing the thigh.40,98 tus medialis TrPs. Meralgia paresthetica has been associ- Sartorius TrPs also may be associated ated with an obese, pendulous, lax ab- with TrPs in its antagonists, the thigh ad- dominal wall;28, 3 1 , 4 0 with tight, constrict- ductors. ing garments or belts;31,32 with shortening of the contralateral lower limb;15, 58 and, in 12A. INTERMITTENT COLD WITH one case, with compression from a wallet STRETCH—SARTORIUS carried in a front pants pocket.84 The sartorius is a uniquely long, slack On examination, patients with meralgia muscle with multiple inscriptions. This paresthetica have sensory changes in the serial arrangement of fibers makes its distribution of the lateral femoral cutane- TrPs relatively difficult to inactivate by ous nerve (Fig. 1 2 . 8 B ) . 1 5 , 3 0 , 4 0 , 6 9 , 1 0 0 Local intermittent cold with stretch. However, tenderness, sometimes with paresthesias if one attempts this technique, the patient and pain projected in the nerve distribu- lies supine with the buttocks at the end of tion, may be elicited by pressure over the the table and holds the thigh of the un-