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

Chapter 16 / Hamstring Muscles 333 Figure 16.11. Stretch positions and intermittent cold abduction to adduction, while the proximal-to-distal patterns (thin arrows) for the right hamstring muscles. application covers all hamstring muscles. Hip flexion is The thick arrows indicate the direction of pressure ap- maintained. C, the thigh is moved toward pure flexion. plied by the operator. The patient is encouraged to D, during full hip flexion, the foot is dorsiflexed at the keep the opposite knee flat on the table. First, the ankle while the gastrocnemius muscle of the calf and thigh is abducted at the hip to release adductor mag- its referred pain zone are included in the proximal-to- nus tightness, and then is adducted toward the midline distal application of cold. E, full flexion and adduction of the body while hip flexion is maintained. Successive at the hip requires an intermittent cold pattern that in- parallel sweeps of the ice or vapocoolant must move cludes the vastus lateralis as well as the adjacent bi- in sequence around the thigh posteriorly from the me- ceps femoris and accessible gluteal muscles. This dial to the lateral side in order to cover the muscles procedure is either preceded by, or followed by, inter- then being stretched. The knee is fully extended mittent cold with stretch of the paraspinal thoracolum- throughout the procedure. A, initial abduction of the bar and sacral muscles and all the gluteal muscles. thigh at the hip; parallel sweeps of spray or ice tra- Between cycles, a pause is usually needed to allow verse the skin over the adductor muscles from distal to rewarming of the skin. proximal. B, start of arcuate crossing movement from

334 Part 2 / Hip, Thigh, and Knee Pain Figure 16.12. Injection of trigger points at their usual seated). A, semitendinosus and semimembranosus, location in the right hamstring muscles (operator B, biceps femoris, long head. Other Methods Before injecting the hamstring muscles, one should review the course of the sci- Postisometric relaxation (as described for atic nerve. It passes down the posterior the biceps femoris58) in combination with thigh underneath the long head of the eye movement and respiration60 is re- biceps femoris muscle, which crosses markably effective for releasing tight over it about midthigh.81 Proximally, the hamstrings. The basic technique is de- nerve reaches the lateral border of the scribed on pages 10—11 of this volume. long head while still deep to the gluteus This procedure is especially valuable as a maximus. Distally, at the popliteal space, self-stretch procedure that can be incor- the nerve's tibial portion emerges from porated in the Long-seated Exercise illus- under the medial border of the long head trated in Figure 16.13. of the biceps femoris about where the semimembranosus muscle and the long Evjenth and Hamberg28 describe and il- head part company.7,76 The femoral blood lustrate a more forceful approach to vessels join the sciatic nerve at about stretching the hamstrings, which empha- this same level by emerging posteriorly sizes the importance of releasing their through the adductor canal from beneath tension, but may be more traumatic than the middle portion of the adductor mag- the stretch techniques described here. nus. The tibial neurovascular bundle then lies deep to the semitendinosus muscle fi- 13. INJECTION AND STRETCH bers and passes down the limb near the (Fig. 16.12) midline behind the knee. The peroneal branch of the sciatic nerve follows beside When injecting hamstring TrPs, it is wise or deep to the medial border of the short to limit treatment to only one side of the head of the biceps femoris to the knee. body on one visit. The patient may expe- rience sufficient postinjection soreness to Semimembranosus and semitendinosus make weight bearing on the treated TrPs can be injected with the patient ly- limb temporarily painful. Two sore lower ing supine, the knee bent, and the thigh limbs could unnecessarily restrict mobil- partially abducted (Fig. 16.12A). The ity. positioning is most convenient for injec- tion if the patient's leg rests on the lap of

Chapter 16 / Hamstring Muscles 335 the seated operator. For TrPs in the distal penetration of a TrP, but may mean only part of the thigh, one grasps at least the that the needle pressed against the TrP medial hamstrings (sometimes it is more without penetrating and disrupting it. effective to grasp all of the hamstrings) in Before leaving one area, the needle is a pincer grasp and pulls the medial ham- withdrawn to a subcutaneous position, strings away from the femur. One can then moved to the side and the region pal- then roll the muscle between the tips of pated for residual TrP tenderness. If pres- the fingers and thumb, examining for taut ent, the residual TrPs are carefully local- bands and spot tenderness. When the lo- ized by palpation and injected. cation of maximum tenderness along the taut bands has been found, this part of the Because one must usually inject multi- band is fixed between the fingers and ple TrPs in these muscles, it is especially thumb so that the needle can be inserted important that, as the needle is with- precisely into the cluster of TrPs. The drawn from the muscle to the skin, pres- needle is directed laterally through the sure by the palpating hand is maintained muscle mass, not toward the femur. The on the injection site to ensure adequate needle is inserted only where it remains hemostasis immediately following injec- palpable between the digits. This avoids tion. Local bleeding as a result of the nee- the popliteal artery and tibial nerve, dling increases postinjection soreness. which lie close to the bone, but not within the pincer grasp. (This is remarka- Postinjection soreness may last for sev- bly similar to the technique used for eral days. The prompt application of a grasping the long head of the triceps moist heating pad over the injected area brachii muscle, page 473 in Volume l.98) for several minutes helps reduce it. The procedure is completed by having the pa- This medial approach requires a 22- tient slowly move the thigh and leg gauge needle about 75 mm (3 in) long, or through the full range of flexion and ex- shorter in small individuals. A 10-mL sy- tension several times to help reestablish ringe is filled with 0.5% procaine solu- normal muscle function. tion, gloves are donned, and the skin area to be injected is cleaned with antiseptic. The patient should be trained in a Injection is performed as described on home self-stretch program for these mus- pages 74-86 in Volume l , 9 8 after ruling cles. out a possible allergy to procaine. The strong neurological interaction between the It is more difficult, but sometimes possi- two lower limbs (crossed reflexes) was demon- ble, to palpate taut bands and TrPs in the strated when phantom pain in a missing lower laterally located long head of the biceps limb was relieved by injecting areas in the other femoris muscle using this pincer tech- normal limb with local anesthetic solution.44 nique. For injection of this muscle, the pa- tient lies on the side opposite to the in- 14. CORRECTIVE ACTIONS volved muscle. If, as usually is the case, flat (Fig. 16.13) palpation must be used to locate the TrPs Repetitive overuse from the crawl stroke (Fig. 16.12B), the needle is inserted close to when swimming should be avoided by in- the midline of the thigh and is directed lat- dividuals with hamstring muscles that are erally, away from the tibial nerve and other prone to develop TrPs. Also to be avoided major neurovascular structures. This ap- is working the hamstrings in a shortened proach also avoids the peroneal branch of position without stretch, as when bicy- the sciatic nerve, unless the most distal cling with too low a seat so that the knees portion of the muscle is being injected. never straighten fully. Figure 16.1 serves as a reminder that fre- Corrective Posture and Activities quently there are multiple TrPs in these Underthigh compression can be avoided muscles. Finding these TrPs requires con- by selecting chairs that match the leg siderable exploration with the needle to length of the sitter, or by propping the ensure that the operator has injected all of feet up on an angled footrest placed a them. A local twitch response confirms short distance in front of the chair (Fig. that a TrP has been impaled. A referred 16.6C). A thick handbag or other object pain response usually indicates needle

336 Part 2 / Hip, Thigh, and Knee Pain Figure 16.13. The Long-seated Reach Exercise for hamstring self-stretch. A, in- itial stretch by slowly and gently sliding the fingers down the shins, keeping the knees straight. B, final stretch. Postiso- metric relaxation coordinated with deep breathing can enhance relaxation in the hamstrings. By grasping and dorsiflexing the feet, the gastrocnemius muscles are also passively stretched. The patient should learn to do this exercise without contracting the abdominal muscles, while exhaling slowly and allowing grav- ity to pull the torso forward. (Contraction of the abdominal muscles in this short- ened position may activate latent trigger points, if present.) can serve as a footrest. Cloth cones filled the Long-seated Reach Exercise (Fig. with sand, which provide a footrest with 16.13). When the ankles are plantar flexed, a range of heights, can be placed under this is primarily a hamstring and long par- the table in front of dining room chairs. aspinal stretch (Fig. 16.13A). The sitting patient reaches as far down the shins as When selecting a chair for the home, one possible while exhaling and consciously should ensure that the front edge of its seat relaxing the back muscles, allowing grav- is rounded and well padded. The seat bot- ity to pull the head and shoulders down toms of patio chairs should be made of firm and forward. Then the patient gently plastic or wood, not of canvas or webbing presses the ankles toward the floor while that sags and places the weight of the thigh slowly inhaling. The patient relaxes again, on a sharp-edged bar at the front of the seat. exhales fully, and slowly reaches further. The importance of this was emphasized by This cycle is repeated until no further a group of apparently normal individuals gains in range of motion occur. who developed thrombophlebitis as the re- sult of impaired venous return during pro- When the ankles are simultaneously longed sitting.49 dorsiflexed by pulling the feet up with the fingers (Fig. 16.13B), stretch of the When driving on long automobile trips, gastrocnemius is included. This self- prolonged immobilization of, and un- stretch exercise is best performed with derthigh pressure on, the hamstring mus- the patient seated in a tub of warm water; cles can be alleviated by using automatic it is illustrated as the In-bathtub Stretch cruise control, which permits changing in Figure 48.13 of Volume l.98 leg position, and by taking frequent \"stretch\" breaks. The seated self-stretch exercise for the gluteus maximus muscle (see Fig. 7.8) also Home Exercise Program helps release hamstring TrP tension. If the A basic stretch exercise that patients with patient with hamstring TrPs also has weak hamstring TrPs should perform at home is gluteus maximus muscles (this often hap-

pens), the weak gluteal muscles must be Chapter 16 / Hamstring Muscles 337 strengthened to eliminate this factor that helps perpetuate the hamstring TrPs. 27. Ericson MO, Nisell R, Arborelius UP, et al.: Muscular activity during ergometer cycling. References Scand J Rehabil Med 77:53-61, 1985. 1. Aftimos S: Myofascial pain in children. N Z 28. Evjenth O, Hamberg J: Muscle Stretching in Man- Med J 702:440-441, 1989. ual Therapy, A Clinical Manual. Alfta Rehab F0rlag, Alfta, Sweden, 1984 (p. 94). 2. Alston W, Carlson KE, Feldman DJ, et al.: A quantitative study of muscle factors in the 29. Ferner H, Staubesand J: Sobotta Atlas of Human chronic low back syndrome. J Am Geriatr Soc Anatomy, Ed. 10, Vol. 2. Urban & Schwarzen- 74:1041-1047, 1966. berg, Baltimore, 1983 (Fig. 381). 3. Anderson JE: Grant's Atlas of Anatomy, Ed. 8. 30. Ibid. (Figs. 401, 403). Williams & Wilkins, Baltimore, 1983 (Figs. 4- 23, 4-24, 4-39). 31. Ibid. (Figs. 410, 411a, 411b). 32. Ibid. (Fig. 412). 4. Ibid. (Fig. 4-26). 33. Ibid. (Fig. 413). 5. Ibid. (Fig. 4-30). 34. Ibid. (Figs. 417, 472) 6. Ibid. (Fig. 4-31). 35. Ibid. (Figs. 418, 419). 7. Ibid. (Fig. 4-34). 36. Ibid. (Figs. 420, 421). 8. Ibid. (Fig. 4-53). 37. Ibid. (Fig. 464). 9. Ibid. (Fig. 4-62A, 4-65A). 38. Ibid. (p. 471). 10. Ibid. (Fig. 4-68). 39. Furlani J, Vitti M, Berzin F: Musculus biceps 11. Baker BA: The muscle trigger: evidence of femoris, long and short head: an electromy- overload injury. J Neurol Orthop Med Surg 7:35- ographic study. Electromyogr Clin Neurophysiol 44, 1986. 77:13-19, 1977. 12. Bardeen CR: The musculature, Sect. 5. In Mor- ris's Human Anatomy, edited by CM. Jackson, 40. Gantchev GN, Draganova N: Muscular siner- Ed. 6. Blakiston's Son & Co., Philadelphia, gies during different conditions of postural ac- 1921 (pp. 506-508). tivity. Acta Physiol Pharmacol Bulg 72:58-65, 1986. 13. Basmajian JV: Grant's Method of Anatomy, Ed. 9. Williams & Wilkins, Baltimore, 1975 (pp. 327, 41. Garrett WE Jr, Califf JC, Bassett FH III: Histo- 328). chemical correlates of hamstring injuries. Am J Sports Med 72:98-103, 1984. 14. Basmajian JV, Burke MD, Burnett GW, et al. (Eds.): Stedman's Medical Dictionary. Williams & 42. Ghori GMU, Luckwill RG: Responses of the Wilkins, 1982 (p. 1288). lower limb to load carrying in walking man. Eur J Appl Physiol 54:145-150, 1985. 15. Basmajian JV, Deluca CJ: Muscles Alive, Ed. 5. Williams & Wilkins, Baltimore, 1985 (pp. 320, 43. Gray DJ: Some anomalous hamstring muscles. 321). Anaf Rec 97:33-38, 1945. 16. Ibid. (pp. 372, 380). 44. Gross D: Contralateral local anesthesia in the 17. Bates T, Grunwaldt E: Myofascial pain in treatment of phantom and stump pain, Re- gional-Anaesthesie 7:65-73, 1984. childhood. J Pediatr 53:198-209, 1958. 18. Baxter MP, Dulberg C: \"Growing Pains\" in 45. Gutstein M: Diagnosis and treatment of muscu- lar rheumatism. Br J Phys Med 1:302-321, 1938 childhood—a proposal for treatment. J Pediatr (Case 7). Orthop 8:402-406, 1988. 19. Brody DM: Running injuries. Clin Symp 32:1- 46. Gutstein M: Common rheumatism and physio- 36, 1980 (see pp. 24-26). therapy. Br J Phys Med 3:46-50, 1940. 20. Broer MR, Houtz SJ: Patterns of Muscular Activity in Selected Sports Skills. Charles C Thomas, 47. Halperin N, Axer A: Semimembranous teno- Springfield, 1967. synovitis. Orthop Rev 9:72-75, 1980. 21. Carter BL, Morehead J, Wolpert SM, et al.: 48. Hellsing A-L: Tightness of hamstring- and Cross-Sectional Anatomy. Appleton-Century- psoas major muscles. Ups J Med Sci 93:267- Crofts, New York, 1977 (Sects. 41-43, 46-48, 276, 1988. 64-72). 49. Homans J: Thrombosis of the deep leg veins 22. Christensen E: Topography of terminal motor due to prolonged sitting. N Engl J Med 250:148- innervation in striated muscles from stillborn 149, 1954. infants. Am J Phys Med 38:65-78, 1959. 50. Joseph J, Williams PL: Electromyography of 23. Clemente CD: Gray's Anatomy of the Human certain hip muscles. J Anaf 91:286-294, 1957. Body, American Ed. 30. Lea & Febiger, Phila- Kamon E: Electromyographic kinesiology of delphia, 1985 (pp. 571-573). jumping. Arch Phys Med Rehabil 52:152-157, 1971. 24. Close JR: Motor Function in the Lower Extremity. Charles C Thomas, Springfield, 1964 (Fig. 66, Kelly M: Some rules for the employment of lo- p. 79). cal analgesia in the treatment of somatic pain. Med J Austral 7:235-239, 1947. 25. Duchenne GB: Physiology of Motion, translated 53. Kelly M: The relief of facial pain by procaine by E.B. Kaplan. J.B. Lippincott, Philadelphia, (Novocain) injections. J Am Geriatr Soc 7 7:586- 1949 (pp. 286, 290-292). 596, 1963 (see p. 589). 26. Ericson M: On the biomechanics of cycling. Kendall FP, McCreary EK: Muscles, Testing and Scand J Rehabil Med (Suppl) 76:1^3, 1986. Function, Ed. 3. Williams & Wilkins, Baltimore, 1983. Lange M: Die Muskelharten (Myogelosen). J.F. Lehmanns, Miinchen, 1931 (pp. 102, 103, Fig. 35).

338 Part 2 / Hip, Thigh, and Knee Pain 56. Lewit K: Manipulative Therapy in Rehabilitation of 84. Okada M: An electromyographic estimation of the Motor System. Butterworths, London, 1985 the relative muscular load in different human (pp. 30, 31, 32, 154). postures. J Human Ergol 1:75-93, 1972. 57. Ibid. (pp. 151, 156, 158, 170, 171, Fig. 4.47). 85. Puranen J, Orava S: The hamstring syndrome: a 58. Ibid. [pp. 280, 281, Fig. 6.100). new diagnosis of gluteal sciatic pain. Am J 59. Ibid. (pp. 309, 314, Table 7.1). Sports Med 76:517-521, 1988. 60. Lewit K: Postisometric relaxation in combina- 86. Rasch PJ, Burke RK: Kinesiology and Applied tion with other methods of muscular facilita- Anatomy, Ed. 6. Lea & Febiger, Philadelphia, tion and inhibition. Manual Med 2:101-104, 1978 (pp. 279, 280, Table 15-1, Table 16-2). 1986. 87. Rask MR: \"Snapping bottom\": subluxation of 61. Lockhart RD: Living Anatomy, Ed. 7. Faber & the tendon of the long head of the biceps fem- Faber, London, 1974 (p. 61). oris muscle. Muscle Nerve 3:250-251, 1980. 62. Lyons K, Perry J, Gronley JK, et al.: Timing and 88. Reynolds MD: Myofascial trigger point syn- relative intensity of hip extensor and abductor dromes in the practice of rheumatology. Arch muscle action during level and stair ambula- Phys Med Rehabil 62:111-114, 1981. tion. Phys Ther 63:1597-1605, 1983. 89. Rohen JW, Yokochi C: Color Atlas of Anatomy, 63. Lyu S-R, Wu J-J: Snapping syndrome caused by Ed. 2. Igaku-Shoin, New York, 1988 (pp. 419, the semitendinosus tendon. J Bone Joint Surg 420). [Am] 71:303-305, 1989. 90. Rubin D: An approach to the management of 64. Mackova J, Janda V, Macek M, et al.: Impaired myofascial trigger point syndromes. Arch Phys muscle function in children and adolescents. J Med Rehabil 62:107-110, 1981. Man Med 4:157-160, 1989. 91. Sherman RA: Published treatments of phantom 65. Maloney M: Personal Communication, 1990. limb pain. Am J Phys Med 59:232-244, 1980. 66. Mann RA, Moran GT, Dougherty SE: Compara- 92. Simons DG: Myofascial pain syndrome due to tive electromyography of the lower extremity trigger points, Chapter 45. In Rehabilitation Med- in jogging, running, and sprinting. Am J Sports icine edited by Joseph Goodgold. C.V. Mosby Med 74:501-510, 1986. Co., St. Louis, 1988 (pp. 686-723, see pp. 710, 711, Fig. 45-8H). 67. Manzano G, McComas AJ: Longitudinal struc- ture and innervation of two mammalian hind- 93. Simons DG, Travell JG: Myofascial pain syn- limb muscles. Muscle Nerve 77:1115-1122, dromes, Chapter 25. In Textbook of Pain, edited 1988. by P.D. Wall and R. Melzack, Ed 2. Churchill Livingstone, London, 1989 (pp. 368-385, see 68. Markhede G, Stener B: Function after removal pp. 271, 272, Fig. 103A). of various hip and thigh muscles for extirpa- tion of tumors. Acfa Orthop Scand 52:373-395, 94. Sugar O: Charles Lasegue and his 'Considera- 1981. tions on Sciatica.' JAMA 253:1767-1768, 1985. 69. McMinn RMH, Hutchings RT: Color Atlas of 95. Townsend MA, Lainhart SP, Shiavi R, et al.: Human Anatomy. Year Book Medical Publishers, Variability and biomechanics of synergy pat- Chicago, 1977 (pp. 264, 270, 275, 277, 281, terns of some lower-limb muscles during as- 282, 285). cending and descending stairs and level walk- ing. Med Biol Eng Comput 76:681-688, 1978. 70. Ibid. (p. 295). 71. Ibid. [p. 304). 96. Travell J: Myofascial trigger points: clinical 72. Milner M, Basmajian JV, Quanbury AO: Multi- view. In Advances in Pain Research and Therapy, edited by J.J. Bonica and D. Albe-Fessard, Vol. factorial analysis of walking by electromy- 1. Raven Press, New York, 1976 (pp. 919-926). ography and computer. Am J Phys Med 50:235- 258, 1971. 97. Travell J, Rinzler SH: The myofascial genesis of pain. Postgrad Med 7 7:425-434, 1952. 73. Moriwaki Y: Electromyographic studies on the knee movements by means of synchronous re- 98. Travell JG and Simons DG: Myofascial Pain and corder. Nihon Univ Med J 27:1394-1404, 1968. Dysfunction: The Trigger Point Manual. Williams & Wilkins, Baltimore, 1983. 74. Murray MP, Mollinger LA, Gardner GM, et al.: Kinematic and EMG patterns during slow, free, 99. Weber EF: Ueber die Langenverhaltnisse der and fast walking. J Orthop Res 2:272-280,1984. Fleischfasern der Muskeln in Allgemeinen. Berichte uber die Verhandlungen der Kdniglich 75. Nemeth G, Ekholm J, Arborelius UP: Hip load Sachsischen Gesellschaft der Wissenschaften zu moments and muscular activity during lifting. Leipzig 3:63-86, 1851. Scand J Rehabil Med 76:103-111, 1984. 100. Weiser HI: Semimembranosus insertion syn- 76. Netter FH: The Ciba Collection of Medical Illustra- drome: a treatable and frequent cause of per- tions, Vol. 8, Musculoskeletal System. Part I: sistent knee pain. Arch Phys Med Rehabil 60: Anatomy, Physiology and Metabolic Disorders. 317-319, 1979. Ciba-Geigy Corporation, Summit, 1987 (p. 82). 101. Wilier J-C, Barranquero A, Kahn M-F, et al.: 77. Ibid. (p. 84). Pain in sciatica depresses lower limb nocicep- 78. Ibid. (p. 85). tive reflexes to sural nerve stimulation. J Neurol 79. Ibid. (p. 86). Neurosurg Psychiatry 50:1-5, 1987. 80. Ibid. (p. 87). 81. Ibid. (p. 91). 102. Yang JF, Winter DA: Surface EMG profiles dur- 82. Ibid. (pp. 94, 95). ing different walking cadences in humans. 83. Oddsson L, Thorstensson A: Fast voluntary Electroencephalogr Clin Neurophysiol 60:485- 491, 1985. trunk flexion movements in standing: motor patterns. Acfa Physiol Scand 729:93-106, 1987.

CHAPTER 17 Popliteus Muscle \"Bent-knee Troublemaker\" HIGHLIGHTS: REFERRED PAIN from trigger tween the semitendinosus tendon and the points (TrPs) in the popliteus muscle concen- medial head of the gastrocnemius muscle. trates in the back of the knee proximal to the The upper, lateral end is best palpated as it location of the TrP. ANATOMICAL ATTACH- crosses the knee joint just above the head of MENTS of this muscle are, proximally, to the the fibula between the tendon of the biceps lateral aspect of the lateral condyle of the fe- femoris on one side and both the gastrocne- mur and, distally, to the posterior aspect of mius muscle's lateral head and the plantaris the tibia medially. The main FUNCTION of the muscle on the other side. For application of popliteus muscle appears to be to \"unlock\" INTERMITTENT COLD WITH STRETCH to the knee at the start of weight bearing by lat- the popliteus muscle, the patient lies prone erally rotating the thigh on the fixed tibia. Ac- with the affected lower leg supported to bend tivity of this muscle prevents forward displace- the knee slightly. Parallel upward sweeps of ment of the femur on the tibia when a person ice or vapocoolant cover the muscle and its crouches, placing weight on the bent knee. pain reference zone while the leg is laterally Generally, the main SYMPTOM of which the rotated to take up the slack that develops. A patient complains is pain behind the knee moist heating pad and then active range of when crouching, running or walking downhill, motion complete this procedure. The patient or going downstairs. A popliteus myofascial continues with self-stretch exercises at home. pain syndrome can readily be misdiagnosed During INJECTION AND STRETCH of popli- as popliteus tendinitis. Other diagnoses teus TrPs, the clinician visualizes the course of that can appear confusingly similar include the popliteal artery and vein and of the tibial and Baker's cyst, anteromedial and posterolateral peroneal nerves and avoids them. The muscle instability of the knee joint, and avulsion of belly can be approached from either its upper the popliteus tendon. ACTIVATION OF TRIG- lateral part or its lower medial part, depending GER POINTS in the popliteus muscle may oc- on where the TrPs are located. CORRECTIVE cur while the person plays soccer or football, ACTIONS to be considered include use of an runs, twists, or slides, especially when run- elastic sleeve around the knee to ameliorate ning or skiing downhill. PATIENT EXAMINA- symptoms and to avoid prolonged immobiliza- TION reveals tenderness of the tendon and tion, if possible. Mechanically, excessive prona- region of attachment of the tendon of the pop- tion of the foot should be corrected. Activities of liteus muscle to the femur. If the patient sits walking, running, or skiing downhill should be with the thigh fixed and the knee bent 90°, avoided during acute flare-ups of pain due to passive lateral rotation of the leg is restricted popliteus TrPs and resumed cautiously after an by pain. For TRIGGER POINT EXAMINA- episode of pain. The best corrective home exer- TION, the popliteus muscle is most accessible cise is postisometric relaxation, and it should be close to the lower (medial) and upper (lateral) a part of the management program of every pa- ends of its muscle belly. The lower, medial tient with this myofascial pain syndrome. end of the muscle is palpated directly be- 339

340 Part 2 / Hip, Thigh, and Knee Pain 1. REFERRED PAIN the lateral meniscus, and to the head of (Fig. 17.1) the fibula via the structure that is gener- ally identified as the arcuate popliteal lig- Trigger points (TrPs) in the popliteus ament on the outer side of the muscle.42 muscle refer pain primarily to the back of Others consider this a distorted view and the knee joint (Fig. 17.1). Patients rarely that this so-called ligament actually con- present with pain in the knee due solely sists of the thickened condensation of fi- to TrPs in the popliteus muscle. Initially, bers from the femoral, fibular, and menis- the source of the knee pain is usually cal origins of the popliteus and posterior identified as coming from TrPs in other capsule of the knee. Together, all of these muscles, such as the gastrocnemius or bi- fibers form a Y-shaped ligamentous at- ceps femoris. On first examination, the tachment of the muscle.28 From both sur- latter appears to account for the patient's faces of its proximal tendon,30 nearly par- pain complaint. However, after the TrPs allel fibers angle diagonally downward45 in these other muscles have been inacti- to attach distally and medially (Fig. 17.2) vated, the patient becomes more aware of to the medial two-thirds of the triangular back-of-the-knee pain that examination surface on the tibia posteriorly, proximal then identifies as originating in the pop- to the soleal line.2,12,39 liteus muscle. 2. ANATOMICAL ATTACHMENTS AND Lovejoy and Harden28 examined in detail the CONSIDERATIONS proximal attachments of the popliteus muscle in (Figs. 17.2 and 17.3) 15 cadaver limbs. They concluded that, in most limbs, it formed a Y-shaped triple attachment. Seen from behind (Fig. 17.2), the thin flat One part always attached to the femur. They con- popliteus muscle has a triangular shape. sidered the second attachment, to the head of the It forms the floor of the distal portion of fibula, to be of phylogenetic origin and of uncer- the popliteal fossa behind the knee. Prox- tain purpose. Murthy36 found the attachment to imally and laterally (Fig. 17.3) it is the fibular head to be missing bilaterally in four of anchored by a strong tendon to the lateral 30 bodies. condyle of the femur, to the capsule of the knee joint with fibers that may include The third attachment intimately connects the tendon with the lateral capsular ligament of the Figure 17.1. Referred pain pattern (dark red) of a trigger point (X) in the right popliteus muscle (light red) seen in posterior view. The essential pain pat- tern is solid red. Red stippling indicates occasional spillover of the essential pat- tern. An additional trigger point is some- times found in the proximal end of the muscle as described in Section 13, In- jection.

Oblique popliteal Chapter 17 / Popliteus Muscle 341 ligament Femur Medial condyle of tibia Fibular collateral ligament Popliteus muscle Arcuate popliteal Tibia ligament Fibula Figure 17.2. Attachments of the right popliteus muscle (red), from a posterior view. Its attachment to the femur is shown in Figure 17.3. knee joint. This third part may play a role in the muscle to the posterior capsule of the knee retraction and protection of the lateral meniscus.30 joint.12,24 Tendinous fibers were secured to the superior margin of the posterior horn of the lateral menis- The popliteus bursa2,5,11,19 separates the cus in 14 of 15 limbs, according to Murthy.38 popliteus tendon from the lateral condyle Questioning this function, Tria and associates50 of the femur just above the head of the fib- dissected 40 cadaver knees to determine the rela- ula. The bursa is usually an extension tion of the popliteus tendon to the lateral menis- of the synovial membrane of the knee cus. Most (83%) of the specimens in this study joint.11 demonstrated no major attachment to the menis- cus. In another study of 60 knees,36 the posterior Supplemental References aspect of the lateral meniscus was attached to the deep surface of the tendon of the popliteus muscle Sources depict the popliteus muscle as drawn in every case. Unquestionably, this meniscal at- from behind without vessels or nerves,5,40 in rela- tachment is of importance in some, possibly in tion to the arcuate popliteal ligament that holds it many, individuals. in place above the head of the fibula,17 and in rela- tion to the bursa of the popliteus muscle.19 It is The popliteus muscle is homologous to the photographed in relation to the arcuate ligament,33 deep portion of the pronator teres muscle in the and in relation to the fibular collateral ligament forearm and is rarely absent.6 and soleus muscle.35 Its structure and fiber direc- tion are visible.45 From behind, one can view the The small fibulotibialis [peroneotibialis] muscle oc- popliteal vessels and tibial nerve crossing over the curred in one body of seven and extended from muscle,3 see the muscle's relation to the overlying the medial side of the head of the fibula to the plantaris muscle,38 and see that it can be palpated posterior surface of the tibia deep to the popliteus directly between the lateral head of the gas- muscle.6,12 Occasionally, a popliteus minor muscle trocnemius muscle and the tendon of the biceps extends from the femur underneath the plantaris

342 Part 2 / Hip, Thigh, and Knee Pain Femur Fibular collateral Rectus femoris ligament tendon (cut) Patella Popliteus muscle Fibula Lateral patellar retinaculum Patellar ligament Tibia Figure 17.3. Proximal attachment of the right popliteus muscle (red) to the femur, from the lateral view. femoris muscle in the posterolateral aspect of the 3. INNERVATION leg near the knee.16 The popliteus muscle is supplied by fi- Lovejoy and Harden28 illustrate the Y-shaped at- bers of the tibial nerve, directly from a tachments to the tibia, lateral meniscus, and fib- branch of the nerve to the tibialis poste- ula in rear view, and the attachments to the tibia rior muscle, and sometimes also by a and fibula in lateral view. branch from the main nerve to the knee joint. These nerve fibers to the popliteus The popliteus muscle is viewed and drawn muscle arise from the fourth and fifth from the lateral side, showing its attachment to lumbar and the first sacral spinal the femur,4,,18 and is photographed also showing nerves.6,12 its relation to the fibular collateral ligament.34 4. FUNCTION The area of its tendinous attachment to the fe- mur, shown in lateral view, indicates an origin Actions within the joint capsule.31 Also shown are the bony attachments to both the femur and tibia from The popliteus muscle rotates the tibia me- behind,39 to the tibia from behind,2,15,32 and to the dially when the thigh is fixed and the leg tibia from the medial view.32 is free to move, as when sitting erect. Dur- ing weight bearing when the leg is fixed, The relation of the popliteus muscle to sur- this muscle rotates the femur laterally on rounding structures is shown in three serial the tibia to \"unlock\" the knee joint.7,12,43 cross sections,10 and in one section below the knee.20 A sagittal section through the middle of The popliteus muscle is at a mechani- the knee joint visualizes the problem of local- cal disadvantage for producing knee flex- ization and injection through the thick soleus ion by virtue of the angulation of its fibers muscle and the lateral head of the gastrocne- and their proximity to the axis of rotation mius muscle.44 of the knee. The popliteus bursa is viewed from be- hind.2,5,11,19

Chapter 17 / Popliteus Muscle 343 Duchenne13 stimulated the popliteus muscle in tive during most of the weight-bearing phase of a freshly amputated leg and found that it strongly gait.7 medially rotated the leg at the knee, and weakly flexed the leg. Human fetal popliteus muscles contained many muscle spindles arranged in complex and tandem Basmajian and Lovejoy8 studied this muscle forms.1 The author concluded that these spindles electromyographically using fine-wire electrodes could provide a major part of the kinesthesia in 20 subjects. These investigators found that, needed to monitor locking and unlocking of the with the leg free to move, the popliteus muscle human knee joint. was activated by voluntary effort to produce me- dial rotation of the leg at knee angles between 5. FUNCTIONAL (MYOTATIC) UNIT knee straight and 90° of flexion in the sitting and prone positions. Medial rotation of the leg by the popliteus muscle is assisted by the medial ham- Functions strings and, to a lesser extent, by the sar- torius and gracilis muscles. Although the The functional relation of this muscle to popliteus has no comparable antagonist its neighboring muscles is comparable to that is primarily a lateral rotator of the that of the pronator teres at the elbow to leg, the biceps femoris muscle provides its neighbors.28,36 They both rotate the dis- some force in that direction. tal part of the limb and seldom present as a single-muscle myofascial syndrome. 6. SYMPTOMS The popliteus responds when activities The chief complaint of patients with ac- require either a force that counters lateral tive TrPs in the popliteus muscle is pain rotation of the tibia on the femur during in the back of the knee when crouching weight bearing,9 or one that prevents the and running or walking, especially going femur from being displaced forward on downhill or downstairs. Patients with the tibial plateau. Its contraction specifi- popliteus TrPs rarely complain of knee cally prevents the lateral femoral condyle pain at night and are frequently not aware from rotating forward off the lateral tibial of their relatively slight decrease in range plateau, as described9,30 and illustrated.9 of motion at the knee or weakness of me- dial rotation of the leg at the knee. Mann and Hagy29 studied both the electromy- Differential Diagnosis ographic (EMG) activity of the popliteus muscle (using fine-wire electrodes) and rotation of the leg Active myofascial TrPs in the popliteus in 10 normal subjects during ambulation and muscle are easily overlooked when a di- other maneuvers involving rotation of the leg. The agnosis of popliteus tendinitis or tenosyn- activity of the popliteus muscle corresponded to ovitis is the focus of attention. Other con- medial rotation of the tibia on the femur during ditions to consider in the differential di- gait and during the other exercises. They con- agnosis of posterior knee pain include cluded that the basic function of the popliteus Baker's cyst, thrombosis of the popliteal muscle is to initiate and maintain medial rotation vein, anteromedial and posterolateral in- of the tibia on the femur. stability of the knee, avulsion of the pop- liteus tendon, and tear of a meniscus or of Basmajian and Lovejoy8 observed that, when a the posterior capsule of the knee joint. person stood in the semicrouched bent-knee posi- tion, the popliteus muscle showed continuous One should be wary of blaming pain in motor unit activity. With the knee thus bent, the the back of the knee on a torn plantaris body weight tends to slide the femur downward muscle months or years after injury. The and forward on the slope of the tibia. Then popli- muscle should have healed. Such resid- teal contraction assists the posterior cruciate liga- ual pain is more likely to be caused by ment in preventing forward dislocation of the fe- TrPs in the popliteus muscle. mur at the knee.7 The muscle is inactive when the person quietly stands erect.7 Popliteus Tendinitis and Tenosynovitis During walking, the greatest EMG activity oc- Popliteus tendinitis and popliteus tenosynovitis curred on heel-strike to unlock the knee joint at the onset of weight bearing. The muscle was ac- are closely associated with activities that would overload an inadequately conditioned popliteus muscle. Mayfield30 reported on 30 patients seen

344 Part 2 / Hip, Thigh, and Knee Pain with the diagnosis of tenosynovitis in a 5-year pe- Remarkably, the history, symptoms, physical riod. The findings leading to this diagnosis are ap- findings, and treatment of popliteus tendinitis parently more common than is generally appreci- and tenosynovitis are similar to what one finds in ated. The characteristic symptom is pain in the patients with TrPs in the popliteus muscle. There lateral aspect of the knee on weight bearing with is no indication that the patients in Mayfield's the knee flexed 15-30°, as when running or walk- study were examined for TrPs, which are not easy ing downhill. Backpacking enthusiasts spent days to locate because the muscle and its TrPs are so ascending into the mountains without symptoms deeply buried in the popliteal region. This clini- until the end of the journey; during rapid descent cal picture points up how easily the tenderness out of the mountains, the symptoms developed.30 produced at the musculotendinous junction by Sometimes pain was also experienced during the the chronic tension placed on that structure by a early part of the swing phase of gait, and on at- taut band of muscle fibers can be identified, while tempting to rise from the cross-legged sitting posi- a TrP origin of the problem may be overlooked. tion.30 Brody\" also noted that symptoms were ag- gravated on the high side when the patient walked Saber's Cyst on a slanted surface or performed some other ac- tivity that excessively pronated the foot during The myofascial pain syndrome of the popliteus weight bearing. muscle mimics the symptoms of a popliteal (Baker's) cyst that produces pain in much the Mayfield30 discussed and illustrated in detail same posterior region of the knee joint. The cyst how to distinguish by physical examination the produces a swelling, often painful, in the pop- tenderness at the origin of the popliteus tendon on liteal space which is caused by enlargement of the the lateral femoral condyle from meniscal tears. bursa that lies deep to the medial head of the gas- For examination, the patient's knee is bent to an trocnemius muscle and/or enlargement of the acute angle by having the seated patient place the semimembranosus bursa, both of which normally ankle of the affected limb on the opposite knee so communicate with the synovial cavity of the knee that the foot hangs down and the tibia is laterally joint. The swelling may be more prominent in the rotated, placing gentle tension on the popliteus standing patient than in the recumbent one. Flex- muscle. A length of about 2 cm of the popliteus ion of the knee increases discomfort. In adults, but tendon is then palpable between the well-defined not in children, the swelling (effusion) usually is landmark of the fibular collateral ligament and the due to disease or injury of the knee joint, such as tendon's attachment to the femur where maxi- rheumatoid arthritis or a meniscal tear. If appro- mum tenderness is found. A distinct separate area priate treatment does not relieve the swelling and of tenderness directly over the meniscus at the pain, the Baker's cyst should be removed surgi- joint line is present in the patient with both a me- cally.23 Although TrPs in the popliteus muscle niscus tear and popliteus tenosynovitis. may exhibit deep tenderness in much the same re- gion as a Baker's cyst, the TrPs do not produce Surgical management was recommended only visible or palpable swelling. Ultrasonography for those patients who had a meniscus tear.30 Con- usually visualizes these cysts well. servative treatment, chiefly elimination of exces- sive popliteus muscle stress, was successful in Rupture of a Baker's cyst may closely simulate most cases of tendinitis or tenosynovitis. thrombophlebitis. The diagnosis of a ruptured cyst is confirmed by an arthrogram that shows en- There were no \"top flight\" competitive runners try of dye from the knee joint into the region of the in Mayfield's series of 30 patients.30 Typically, the calf muscles.26 patients with this diagnosis of tenosynovitis were relatively sedentary individuals who stressed the Anteromedial and Posterolateral Instability of the knee by suddenly increasing activity. The ilio- Knee tibial band friction syndrome and stress reaction of the biceps femoris tendon can be distinguished The popliteus muscle is a major contributor to ro- by accurately localizing tenderness over appropri- tational stability of the knee joint. Lateral rotation ate anatomical structures.30 of the tibia on the femur in the last few degrees of extension \"locks\" the knee, firmly uniting the Of the 20 patients on whom radiographs of the thigh and leg into a single structure.48 In the func- knee were taken, five showed radiopacities of ap- tioning athlete, anteromedial instability results parent calcific deposits in the area of the pop- from excessive medial rotation of the femur on the liteus tendon.30 This may be another example of fixed tibia with the knee in flexion and leads to calcification of a tendon subjected to chronic ten- \"giving way\" of the knee when the runner \"cuts\" sion due to latent or active TrPs (see Volume 1, away from his supporting leg.48 Chapter 21, Supraspinatus Muscle).49

Chapter 17 / Popliteus Muscle 345 Surgically shortening the popliteus muscle-ten- mediately painful and became swollen.37 Ar- don unit, which was elongated or torn in eight pa- tients, resulted in static and dynamic stability and throtomy demonstrated the retracted popliteus return to full function in seven of them. None of the eight experienced any loss of power in the tendon. The lateral meniscus was intact.37 popliteus muscle.48 Depending on which liga- ments are lax or torn, excessive medial rotation of In another report,46 arthroscopy, electromy- the femur on the tibia produces either rotary anteromedial instability48 or rotary posterolateral ography, and Cybex testing established the diag- instability.21,47 In either condition, surgical reloca- tion of the tibial attachment of the popliteus mus- nosis of popliteus tendon rupture. Surgical repair cle in order to shorten it, increases its tension, im- proves its dynamic function, and corrects the of a ruptured popliteus tendon in these two pa- problem. One report described four patients who, with the knee flexed 80-90°, could produce vol- tients followed failure of conservative therapy. untary anterior subluxation of the lateral tibial plateau by contracting the popliteus muscle.42 Both patients returned to their preinjury levels of Six of ten patients (over half of those studied activity. with the posterolateral drawer sign)47 were able voluntarily to evoke the posterolateral drawer sign 7. ACTIVATION AND PERPETUATION in the knee with posterolateral instability. The re- OF TRIGGER POINTS maining four patients learned to perform this ma- neuver. This posterior subluxation of the tibial The TrPs may be activated in the pop- plateau seriously interferes with descending stairs liteus muscle while an individual plays and participating in sports activities. Electromy- soccer or football, runs, twists, slides, ography in three of the patients demonstrated that and, especially, while running or skiing contraction of the biceps femoris muscle pro- downhill. This muscle is specifically duced the subluxation, contraction of the pop- overloaded by braking the forward mo- liteus muscle reduced it, and that neither the rectus tion of the femur on the tibia during a femoris nor gastrocnemius muscles participated.47 twisting turn with the body weight on a The authors recommended that, when this condi- slightly bent knee of the side toward tion is suspected from the history, the patient ini- which the body is turning. tially should demonstrate the knee problem to the examiner. This is generally painless and, therefore, Overload that causes a tear of the plan- is not distorted by interfering muscle tension in- taris muscle may also activate TrPs in the duced by the patient's fear of the examiner's test- popliteus muscle. ing.47 Surgical relocation of the tendon attachment was considered effective because the popliteus A trauma or strain that tears the poste- muscle is a dynamic musculotendinous unit and rior cruciate ligament of the knee may not a static stabilizer like a ligament.25 also overload and strain the popliteus muscle. Brody9 reported an association between an excessively pronated foot during weight-bearing activities and aggravation of popliteus tendinitis symptoms. The added stress from excessive pronation could also perpetuate TrPs in the pop- liteus muscle. 8. PATIENT EXAMINATION Misdiagnosis of Popliteus Tendon If the popliteus muscle harbors TrPs, the In one study,22 magnetic resonance imaging of the knee is painful when the patient attempts normal popliteus tendon was sometimes mistaken to extend it fully. for a tear in the posterior horn of the lateral menis- cus. In another study of 200 knees,51 the bursa of The tibial attachment and tendon of the the popliteus tendon simulated a tear of the poste- popliteus muscle should be examined for rior horn of the lateral meniscus in 27.5% of the tenderness. The position described and il- knees studied by magnetic resonance imaging. lustrated to examine the knee for pop- liteus tendinitis9,30 may be used also for Avulsion Of Popliteus Tendon examining the femoral end of the muscle and its tendon. The seated patient places Two cases of reported avulsion or rupture of the the leg of the affected limb on the oppo- popliteus tendon occurred when one individual site knee, with the foot hanging relaxed. was pushing a car48 and when the other, an ath- The proximal attachment of the popliteus lete, was running in a football game.37 The athlete tendon on the lateral side of the femoral tried to stop and change direction with the condyle is examined for tenderness and weight-bearing knee in flexion. The knee was im- the tendon palpated along the 2-cm dis-

346 Part 2 / Hip, Thigh, and Knee Pain Figure 17.4. Palpation of a trigger point in the lower medial part of the right popliteus muscle. The solid circle marks the medial condyle of the tibia, and the arrow shows the direction of pressure. The knee is flexed, and the foot plantar flexed at the ankle to slacken the gas- trocnemius and plantaris muscles. Lat- eral rotation of the leg increases tension on the popliteus muscle by placing it on a slight stretch. To explore directly the trigger point area and region of tibial at- tachment of the popliteus muscle, the palpating digit, in this case the exam- iner's thumb, pushes down and anteri- orly, just medial to the laterally displaced medial head of the gastrocnemius mus- cle, between it and the semitendinosus tendon. tance proximal to the point where it is approachable between the semitendi- passes posteriorly deep to the fibular col- nosus tendon and the medial head of the lateral ligament, which is a well-defined gastrocnemius muscle.10 The most distal landmark (Fig. 17.3).30 The TrP tightness portion of the tibial attachment of the of the popliteus muscle restricts the range popliteus is covered by the soleus mus- of passive lateral rotation and weakens cle,10 which can usually be displaced lat- active medial rotation of the leg with the erally to uncover the popliteus partially. knee flexed nearly 90°. This medial, distal end of the popliteus muscle is examined for TrPs as illustrated The relatively small restriction of full in Figure 17.4. It is important to displace knee extension (usually only 5° or possi- the overlying muscles laterally when do- bly 10°) is often not clearly appreciated ing this part of the examination. until retesting after treatment. Only then is the full range of normal extension for In the popliteal space, the upper lateral that patient's knee identified. end of the popliteus muscle is covered by the plantaris muscle and the lateral head 9. TRIGGER POINT EXAMINATION of the gastrocnemius muscle. However, as (Fig. 17.4) the popliteus muscle crosses the leg diag- onally just above the head of the fibula The popliteus muscle is palpated for TrPs (Fig. 17.2), one can reach it by palpating with the patient lying on the affected side between the tendon of the biceps femoris and the knee slightly flexed (Fig. 17.4). laterally and the lateral head of the gas- The leg extends over the edge of the ex- trocnemius muscle and the plantaris mus- amining table and rests on the lap of the cle medially.16 With the patient in the po- seated operator, with the leg in slight lat- sition of Figure 17.4, one can often dis- eral rotation and the foot in moderate place these overlying muscles to the side plantar flexion. The slight flexion of the with one hand while palpating for TrP leg at the knee slackens the overlying gas- tenderness with the other. If the popliteus trocnemius muscle; the plantar flexed muscle has active TrPs, this spot is tender foot further slackens the gastrocnemius and pressure on it causes diffuse pain re- and plantaris muscles; the lateral rotation ferred throughout the back of the knee. of the leg places the popliteus muscle on The region of attachment of the popliteus a slight stretch and can be adjusted to in- tendon onto the tibia is also tender. crease tenderness of the popliteus TrPs for examination. If the popliteus TrPs are sufficiently ir- ritable, their tenderness may be elicited The medial side of the mid-part of the by pressure exerted straight in, through muscle, along its attachment to the tibia, the overlying muscles; these include the

Chapter 17 / Popliteus Muscle 347 With the foot dorsiflexed, the degree of pain in the popliteal fossa and restriction of motion at the knee caused by TrPs in the lateral head of the gastrocnemius muscle is comparable to that caused by TrPs in the popliteus muscle. 12. INTERMITTENT COLD WITH STRETCH (Fig. 17.5) Figure 17.5. Stretch position and direction of appli- For many years, treatment of the pop- cation (thin arrows) of parallel sweeps of intermittent liteus muscle by intermittent cold with cold (ice or vapocoolant spray) for a trigger point (X) in stretch produced poor results by simply the right popliteus muscle. The knee is held in slight extending the knee. However, results im- flexion to avoid locking the knee, which would prevent proved remarkably when the leg was ro- rotation of the leg at that joint. Large arrow identifies tated laterally with slightly less than full the lateral direction of leg rotation (applied at the an- extension of the knee. Slight flexion at the kle) to lengthen the popliteus muscle passively. The knee is essential to avoid locking its ro- thigh is fixed by its weight on the examining table. tary motion. soleus, the proximal end of which runs Techniques that augment relaxation nearly parallel with the popliteus muscle and stretch are reviewed on page 11 and fibers and covers the distal half of them.38 alternative treatment methods are re- It is difficult to distinguish TrP tender- viewed on pages 9-11 of this volume. ness unambiguously in the intermediate portions of the popliteus muscle from the The patient is placed prone with a pil- spot tenderness of TrPs in the intervening low under the leg, just above the ankle musculature. (Fig. 17.5) to flex the knee slightly. Using the principles of postisometric relaxa- 10. ENTRAPMENTS tion,27 the patient first slowly takes in a full breath and then exhales slowly and No nerve entrapments due to TrPs in this fully while consciously trying to relax the muscle are identified. muscles. During the patient's exhalation, the clinician applies intermittent cold 11. ASSOCIATED TRIGGER POINTS (ice, described in Chapter 2, page 9, or va- pocoolant spray described on pages 6 7 - The TrPs in the proximal portion of either 74 in Volume l 4 9 ) in parallel lines diago- or both heads of the gastrocnemius mus- nally upward across the back of the knee cle are the ones most commonly associ- to cover the muscle and the referred pain ated with TrPs in the popliteus muscle. In zone (Fig. 17.5); simultaneously, the cli- a few patients, popliteus TrPs have been nician takes up any slack in lateral rota- associated with a tear of the plantaris tion of the leg. The patient, while slowly muscle and may have been activated taking in the next breath, then gently tries when the plantaris was torn. to rotate the leg medially against resist- ance by the operator. While exhaling slowly, the patient \"lets go\" and relaxes. This cycle may be repeated several times until full range of lateral rotation of the leg has been restored and the TrPs have lost their spot tenderness. Between cy- cles, care is taken to rewarm the skin. After prompt application of a moist heating pad or hot pack, the seated pa- tient actively rotates the leg slowly through full medial and lateral rotary range of motion for several cycles to re- store the full functional range.

348 Part 2 / Hip, Thigh, and Knee Pain The popliteus TrPs located over the tibia are responsive to ischemic compres- sion or deep stretching massage when compressed against the bone.41 Pressure on the overlying midline neurovascular trunk must be avoided. Evjenth and Ham- berg14 describe and illustrate a stretch technique with the patient supine and the knee resting on a cushion and bent about 10°. The leg is laterally rotated fully and gradually brought into extension. This technique has the disadvantage that the supine positioning precludes simultane- ous application of intermittent cold. Such passive stretch for releasing popliteus TrPs should be combined with postiso- metric relaxation techniques as described in Chapter 2 and by Lewit.27 The clinician should instruct the pa- tient in a home stretch program, as de- scribed in Section 14 of this chapter. 13. INJECTION AND STRETCH (Fig. 17.6) When injecting popliteus TrPs, it is im- Figure 17.6. Injection of trigger points in the lower portant to remember that the popliteal ar- medial part of the right popliteus muscle. The solid cir- tery and vein and tibial nerve descend cle locates the medial condyle of the tibia. The medial through the midline of the popliteal head of the gastrocnemius muscle is pressed aside space, first between and then underneath posterolaterally to uncover the popliteus trigger point; the two heads of the gastrocnemius mus- the gastrocnemius is partially slackened by plantar cle, while resting on the underlying pop- flexing the foot at the ankle, while the knee is slightly liteus muscle. Laterally, the peroneal flexed to permit slackening of popliteus muscle ten- nerve courses deep to the medial edge of sion. the biceps femoris muscle and tendon, crossing superficially over the popliteus, orly. One should not expect to see a local plantaris, and gastrocnemius (lateral twitch response in this deep muscle; it head) muscles.3,38,44 may be palpable through the needle. With the patient side lying, any TrPs in When the TrP tenderness is elicited to- the medial part of the popliteus muscle ward the upper lateral end of the muscle, are identified by palpation as described one must be careful when inserting the previously in Section 9, Trigger Point Ex- needle to keep the point of penetration amination. The palpating hand displaces medial to the biceps femoris muscle and the medial head of the gastrocnemius tendon to avoid the peroneal nerve that aside laterally toward the middle of the courses medial or deep to them. The TrP leg. A 38-mm (l1/2in) 22-gauge needle is tenderness in this upper part of the pop- inserted on the medial side of the back of liteus muscle is identified as described the leg, through the skin medial to the previously in Section 9, Trigger Point Ex- spot tenderness so that the needle will amination. Unless the patient is unusually enter deep to and medial to the neurovas- large, the same size needle is used here as cular bundle in the midline of the leg for injecting the other part of the muscle. (Fig. 17.6). When the needle encounters an active TrP, the clinician is likely to The TrPs are injected with 0.5% pro- feel the local twitch response with the caine in isotonic saline. The injection palpating hand, and the patient describes pain referred into the knee joint posteri-

Chapter 17 / Popliteus Muscle 349 technique is described in detail on pages Effort should be made to limit walking 74-86 of Volume l . 4 9 Immediately after or running on laterally sloped surfaces injection, care is taken to maintain pres- (which increases pronation of the foot sure for hemostasis at the injection site and the effect of a longer lower limb on with the free palpating hand. the high side). Running can be performed on a track, on the crown of an isolated After injection, the clinician applies a road, or one can run on the same side of moist heating pad over the region of the the road for both directions of the trip. popliteus muscle for several minutes to Appropriate shoe inserts should be uti- relax the muscle further and to reduce lized if indicated. postinjection soreness. Home Exercise Program Then, the seated patient actively rotates the flexed leg slowly through full medial Self-stretch of the popliteus muscle may and lateral rotation for several cycles, and be performed in the prone or seated posi- then through knee flexion and extension, tion. In each position, the knee is flexed exercising full range of motion. 15-20°. Reciprocal inhibition can be used instead of passive stretch, if no one is Before the patient leaves, the clinician available to be instructed as an assistant ensures that the patient understands how at home. to perform the home exercise (see next section). For the prone position, the patient as- sumes the position illustrated in Figure 14. CORRECTIVE ACTIONS 17.5 with enough blanket roll or pillow under the distal leg to flex the knee 1 5 - The patient may wear an elastic sleeve 20°. The patient tries to rotate the leg lat- (knee support) that extends from above erally for several seconds (reciprocally in- the knee to below it; this elastic support hibiting the popliteus), and then relaxes can be obtained with an opening in front fully. The cycle is repeated a few times. for the patella, and must be properly fit- The advantage of this position is that the ted. This device is consistently helpful thigh is stabilized so that the leg, rather and worth using as long as symptoms per- than the thigh, rotates. If the blanket roll sist. It applies counter pressure over the or pillow touches the foot, the friction region of the TrPs, reducing their sensi- may help to maintain lateral rotation dur- tivity, and it reminds the patient that the ing relaxation. Otherwise, gravity pulls knee should be protected. the foot and leg back into neutral posi- tion. Splinting or immobilizing the knee and leg with a brace or cast tends to aggravate For relaxation of the popliteus in the popliteus TrPs. When popliteus TrPs sitting position, the seated patient places present a problem, it is preferable that im- the leg forward with the heel on the floor mobilization be avoided or the period of and the knee flexed 15-20°. A low-seated immobilization be minimized. bench or chair may be required. Since thigh rotation is often substituted for leg Corrective Posture and Activities rotation in this position, special care must be taken to ensure that the patient If one plans to go skiing and is concerned knows the difference and achieves lateral about popliteus TrPs, training should be rotation of the leg at the knee. After a undertaken to condition the muscle grad- maximal lateral rotation effort for several ually; a vitamin C supplement should be seconds, the patient relaxes fully while taken before this strenuous activity. The gravity tends to maintain the lateral rota- lower limbs should be kept warm. tion. This cycle is repeated at least three times with a pause between each cycle. Individuals prone to popliteus TrPs should avoid a sudden major increment Each stretching session is completed in the amount of running or walking with full active range of motion through downhill that is beyond the level to medial and lateral rotation of the leg, and which they are accustomed. then through knee flexion and extension. High heels should be avoided because wearing them is tantamount to continu- ously walking downhill.

350 Part 2 / Hip, Thigh, and Knee Pain References W. B. Saunders, Philadelphia, 1985 (pp. 3 5 3 - 1. Amonoo-Kuofi HS: Morphology of muscle spin- 364, see p. 364). dles in the human popliteus muscle. Evidence 27. Lewit K: Postisometric relaxation in combina- of a possible monitoring role of the popliteus tion with other methods of muscular facilita- muscle in the locked knee joint? Acta Anatomica tion and inhibition. Manual Med 2 : 1 0 1 - 1 0 4 , 734:48-53, 1989. 1986. 2. Anderson JE: Grant's Atlas of Anatomy, Ed. 8. Wil- 28. Lovejoy JF, Jr, Harden TP: Popliteus muscle in liams & Wilkins, Baltimore, 1983 (Figs. 4-24, 4- man. Anat Rec 7 6 9 : 7 2 7 - 7 3 0 , 1 9 7 1 . 50). 29. Mann RA, Hagy JL: The popliteus muscle. J 3. Ibid. (Figs. 4 - 5 3 , 4 - 8 6 ) . Bone Joint Surg [Am] 5 9 : 9 2 4 - 9 2 7 , 1977. 4. Ibid. (Fig. 4 - 6 7 ) . 5. Ibid. (Fig. 4 - 6 8 ) . 30. Mayfield GW: Popliteus tendon tenosynovitis. 6. Bardeen CR: The musculature, Sect. 5. In Mor- Am J Sports Med 5 : 3 1 - 3 6 , 1977. ris's Human Anatomy, edited by C M . Jackson, Ed. 3 1 . McMinn RMH, Hutchings RT: Color Atlas of Human Anatomy. Year Book Medical Publishers, 6. Blakiston's Son & Co., Philadelphia, 1921 (p. Chicago, 1977 (p. 277). 518). 32. Ibid. (pp. 281, 282). 7. Basmajian JV, Deluca CJ: Muscles Alive, Ed. 5. 33. Ibid. (p. 307D). 34. Ibid. (p. 308C). Williams & Wilkins, Baltimore, 1985 (pp. 259, 3 5 . Ibid. (p. 315C). 332-334). 36. Murthy CK: Origin of popliteus muscle in man. J Ind Med Assoc 6 7 : 9 7 - 9 9 , 1 9 7 6 . 8. Basmajian JV, Lovejoy JF, Jr: Functions of the 37. Naver L, Aalberg JR: Avulsion of the popliteus popliteus muscle in man: a multifactorial elec- tromyographic study. J Bone Joint Surg [Am] 53: tendon, a rare cause of chondral fracture and hemarthrosis. Am J Sports Med 73:423^124, 557-562, 1971. 9. Brody DM: Running injuries. Clinical Symposia 1985. 38. Netter FH: The Ciba Collection of Medical Illustra- 32:1-36, 1980 (pp. 15, 16). 10. Carter BL, Morehead J, Wolpert SM, et al.: Cross- tions, Vol. 8, Musculoskeletal System. Part I: Sectional Anatomy. Appleton-Century-Crofts, New Anatomy, Physiology and Metabolic Disorders. York, 1977 (Sects. 71-73). Ciba-Geigy Corporation, Summit, 1987 (pp. 85, 1 1 . Clemente CD: Gray's Anatomy of the Human Body, 101). American Ed. 30. Lea & Febiger, Philadelphia, 39. Ibid. (pp. 86, 107). 4 0 . Ibid. (p. 95). 1985 (p. 406). 12. Ibid. (pp. 5 7 7 - 5 7 8 ) . 41. Nielsen AJ: Personal Communication, 1989. 13. Duchenne GB: Physiology of Motion, translated by 42. Peterson L, Pitman MI, Gold J: The active pivot E.B. Kaplan. J. B. Lippincott, Philadelphia, 1949 shift: the role of the popliteus muscle. Am J Sports Med 7 2 : 3 1 3 - 3 1 7 , 1984. (pp. 286, 291-292). 14. Evjenth O, Hamberg J: Muscle Stretching in Man- 43. Rasch PJ, Burke RK: Kinesiology and Applied Anat- omy, Ed. 6. Lea & Febiger, Philadelphia, 1978 ual Therapy, A Clinical Manual. Alfta Rehab Forlag, (pp. 292, 309, Table 16-2). Alfta, Sweden, 1984 (p. 132). 44. Rohen JW, Yokochi C: Color Atlas of Anatomy, Ed. 15. Ferner H, Staubesand J: Sobotta Atlas of Human 2. Igaku-Shoin, New York, 1988 (p. 412). Anatomy, Ed. 10, Vol. 2. Urban & Schwarzen- 4 5 . Ibid. (p. 4 2 4 ) . berg, Baltimore, 1983 (Figs. 420, 469). 46. Rose DJ, Parisien JS: Popliteus tendon rupture. 16. Ibid. (Fig. 4 3 6 ) . Case report and review of the literature. Clin 17. Ibid. (Fig. 4 4 0 ) . Orthop 2 2 6 : 1 1 3 - 1 1 7 , 1988. 18. Ibid. (Fig. 4 4 3 ) . 19. Ibid. (Fig. 4 4 4 ) . 47. Shino K, Horibe S, Ono K: The voluntarily 20. Ibid. (Fig. 4 7 2 ) . evoked posterolateral drawer sign in the knee 2 1 . Fleming RE Jr, Blatz DJ, McCarroll JR: Posterior with posterolateral instability. Clin Orthop 215: problems in the knee, posterior cruciate insuffi- 179-186, 1987. ciency and posterolateral rotary insufficiency. 48. Southmayd W, Quigley TB: The forgotten pop- Am J Sports Med 9 : 1 0 7 - 1 1 3 , 1981. liteus muscle, its usefulness in correcting an- 22. Herman LJ, Beltran J: Pitfalls in MR imaging of the knee. Radiology 1 6 7 : 7 7 5 - 7 8 1 , 1 9 8 8 . teromedial rotatory instability of the knee; a pre- liminary report. Clin Orthop 7 3 0 : 2 1 8 - 2 2 2 , 1978. 23. Hollinshead WH: Anatomy for Surgeons, Ed. 3, 49. Travell JG, Simons DG: Myofascial Pain and Dys- Vol. 3, The Back and Limbs. Harper & Row, New function: The Trigger Point Manual. Williams & York, 1982 (pp. 751-752). Wilkins, Baltimore, 1983. 24. Ibid. (pp. 7 7 8 - 7 7 9 ) . 50. Tria AJ Jr, Johnson CD, Zawadsky JP: The pop- 25. Hughston JC, Jacobson KE: Chronic postero- liteus tendon. J Bone Joint Surg [Am] 7 1 : 7 1 4 - 7 1 6 , lateral rotatory instability of the knee. J Bone Joint Surg [Am] 6 7 : 3 5 1 - 3 5 9 , 1 9 8 5 . 1989. 26. Kontos HA: Vascular diseases of the limbs due 51. Watanabe AT, Carter BC, Teitelbaum GP, et al.: to abnormal responses of vascular smooth mus- Common pitfalls in magnetic resonance imaging cle, Chapter 54. In Cecil Textbook of Medicine, ed- of the knee. J Bone Joint Surg [Am] 7 7 : 8 5 7 - 8 6 2 , ited by J.B. Wyngaarden, L.H. Smith, Jr., Ed. 17. 1989.

PART 3 CHAPTER 18 Leg, Ankle, and Foot Pain-and-Muscle Guide INTRODUCTION TO PART 3 responsible for referred pain in each of the areas shown in Figure 18.1. These ar- This third part of THE TRIGGER POINT eas, which identify where patients may MANUAL includes the muscles of the complain of pain, are listed alphabeti- leg, ankle, and foot. Differential diagnosis cally. The muscles most likely to refer of an individual muscle's referred pain pain to each designated area are listed pattern is considered under Section 6, under the name of that area. One uses this Symptoms, in each muscle chapter. chart by locating the name of the area that hurts and then by looking under that This chapter also includes an illustra- heading for the muscles that are likely to tion of the bones of the foot (Fig. 18.2) for cause the pain. Reference should then be a ready reference to the relations among made to the pain patterns of individual these bones. An understanding of these muscles, as indicated by the figure and structural relations is essential for com- page numbers in parentheses. prehending the functions of the intrinsic foot muscles that are covered in Chapters In a general way, the muscle listings 26 and 27. The last chapter of Part 3 in- follow the order of frequency in which cludes an overview of the management of they are likely to cause pain in that area. chronic myofascial pain syndromes. It ex- This order is only an approximation; the plains how one integrates the information selection process by which patients reach from the various chapters of Volume l2 an examiner greatly influences which of and Volume 2 of THE TRIGGER POINT their muscles are most likely to be symp- MANUAL to solve the puzzling pain tomatic. Bold face type indicates that the problems of the patient with chronic muscle refers an essential pain pattern to myofascial pain. that pain area. Normal type indicates that the muscle may sometimes refer pain (a PAIN GUIDE TO INVOLVED MUSCLES spillover pattern) to that pain area. TrP means trigger point. This guide lists the muscles that may be 351

352 Part 3 / Leg, Ankle, and Foot Pain-and-Muscle Guide Posterior leg pain Lateral leg pain Anterior leg pain Posterior ankle pain Lateral ankle pain Medial ankle pain Heel pain Plantar midfoot pain Anterior ankle pain Metatarsal head pain Plantar lesser toe pain Dorsal forefoot pain Dorsal lesser toe pain Dorsal great toe pain Plantar great toe pain Front view Rear view Posterior leg pain Lateral leg pain Anterior leg pain Anterior ankle pain Posterior ankle pain Dorsal forefoot pain Lateral ankle pain Dorsal great toe pain Heel pain Dorsal lesser toe pain Lateral view Figure 1 8 . 1 . Designated areas (red) within the leg, myofascial pain. The pain may be referred to each ankle, and foot regions where patients may describe area from the muscles listed in the PAIN GUIDE. PAIN GUIDE Interossei of foot (27.3A, p. 525) Tibialis anterior (19.1, p. 356) ANTERIOR ANKLE PAIN DORSAL GREAT TOE PAIN Tibialis anterior (19.1, p. 356) Peroneus tertius (20.1B, p. 372) Tibialis anterior (19.1, p. 356) Extensor digitorum longus (24.1A, p. 474) Extensor hallucis longus (24.16, p. 474) Extensor hallucis longus (24.16, p. 474) Flexor hallucis brevis (27.2B, p. 524) ANTERIOR LEG PAIN DORSAL LESSER TOE PAIN Tibialis anterior (19.1, p. 356) Interossei of foot (27.3A, p. 525) Adductors longus and brevis (15.1, p. 291) Extensor digitorum longus (24.1A, p. 474) DORSAL FOREFOOT PAIN HEEL PAIN Extensor digitorum brevis and extensor hal- Soleus (22.1 TrP1 p. 429) lucis brevis (26.1, p. 503) Quadratus plantae (27.1, p. 523) Abductor hallucis (26.2, p. 504) Extensor digitorum longus (24.1A, p. 474) Tibialis posterior (23.1, p. 461) Extensor hallucis longus (24.16, p. 474) Flexor hallucis brevis (27.26, p. 524)

Chapter 18 / Introduction 353 LATERAL ANKLE PAIN PLANTAR MIDFOOT PAIN Peronei longus and brevis (20.1A, p. 372) Gastrocnemius (21.1 TrP1, p. 399) Peroneus tertius (20.1B p. 372) Flexor digitorum longus (25.1A, p. 490) Adductor hallucis (27.2A, p. 524) LATERAL LEG PAIN Soleus (22.1 TrP1, p. 429) Interossei of foot (27.3B, p. 525) Gastrocnemius (21.1 TrP2, p. 399) Abductor hallucis (26.2, p. 504) Gluteus minimus, anterior section (9.1, p. 169) Tibialis posterior (23.1, p. 461) Peronei longus and brevis (20.1A, p. 372) Vastus lateralis (14.4 TrP2, p. 253) POSTERIOR ANKLE PAIN MEDIAL ANKLE PAIN Soleus (22.1 TrP1, p. 429) Tibialis posterior (23.1, p. 461) Abductor hallucis (26.2, p. 504) Flexor digitorum longus (25.1A, p. 490) POSTERIOR LEG PAIN METATARSAL HEAD PAIN Flexor hallucis brevis (27.2B, p. 524) Soleus (22.1 TrP2, p. 429) Flexor digitorum brevis (26.3B, p. 505) Gluteus minimus, posterior section (9.2, Adductor hallucis (27.2A, p. 524) Flexor hallucis longus (25.1B, p. 490) p. 169) Interossei of foot (27.3B, p. 525) Gastrocnemius (21.1, p. 399) Abductor digiti minimi (26.3A, p. 505) Semitendinosus and semimembranosus (16.1, Flexor digitorum longus (25.1A, p. 490) Tibialis posterior (23.1, p. 461) p. 317) Soleus (22.1 TrP1, p. 429) PLANTAR GREAT TOE PAIN Flexor digitorum longus (25.1A, p. 490) Tibialis posterior (23.1, p. 461) Flexor hallucis longus (25.18, p. 490) Plantaris (22.3, p. 430) Flexor hallucis brevis (27.28, p. 524) Tibialis posterior (23.1 p. 461) References PLANTAR LESSER TOE PAIN 1. M c M i n n RMH, Hutchings RT, Logan B M : Color Atlas of Foot and Ankle Anatomy. Appleton-Cen- Flexor digitorum longus (25.1A, p. 490) tury-Crofts, Connecticut, 1982 (p. 26). Tibialis posterior (23.1, p. 461) 2. Travell JG, Simons DG: Myofascial Pain and Dys- function: The Trigger Point Manual. Williams & Wilkins, Baltimore, 1983.

354 Part 3 / Leg, Ankle, and Foot Pain-and-Muscle Guide Distal phalanges Middle phalanx of second toe Proximal phalanx of second toe Proximal phalanx of great toe Sesamoid bones 1st metatarsal 2nd metatarsal 3rd metatarsal 4th metatarsal 5th metatarsal Medial cuneiform Intermediate cuneiform Lateral cuneiform Navicular Cuboid Talus Calcaneus Dorsal view Left foot Plantar view Figure 18.2. Bones of the left foot from A, the dorsal view, and S, the plantar view. Redrawn from McMinn et al.1

CHAPTER 19 Tibialis Anterior Muscle \"Foot-drop Muscle\" HIGHLIGHTS: REFERRED PAIN from trigger tenderness in the referred pain zone, slight points (TrPs) in the tibialis anterior muscle con- weakness, and some restriction of the stretch centrates on the anteromedial aspect of the an- range of motion of the tibialis anterior muscle. kle and on the dorsal and medial surfaces of the TRIGGER POINT EXAMINATION reveals taut great toe. A spillover pattern may extend down- bands parallel to the tibia with spot tenderness ward over the shin from the TrP to the ankle. of TrPs in the upper one-third of the muscle. ANATOMICAL ATTACHMENTS anchor proxi- Snapping palpation at the TrP evokes highly vis- mally to the lateral condyle of the tibia, the upper ible local twitch responses, and digital pressure half or more of the lateral surface of the body of reproduces the referred pain pattern of active the tibia, and to surrounding fascial structures. TrPs. To employ INTERMITTENT COLD WITH The muscle's tendon attaches distally to the me- STRETCH, the clinician applies ice or vapocool- dial and plantar surfaces of the medial cunei- ant spray in parallel sweeps downward over the form bone and to the base of the first metatarsal. muscle and its referred pain pattern. At the FUNCTIONS of the tibialis anterior muscle dur- same time, passive plantar flexion and eversion ing ambulation are to prevent foot slap at heel- of the foot lengthen the muscle. This technique strike and to help the toes clear the floor during can be augmented by postisometric relaxation swing phase. It is vigorously active during jog- and reciprocal inhibition. Massage can be effec- ging, running, sprinting, two-leg upward jumps, tive for inactivating tibialis anterior TrPs. INJEC- and other sports activities. It acts as a dor- TION AND STRETCH of this muscle employs a siflexor of the foot at the talocrural joint and acts 21 -gauge, 38-mm (11/2-in) needle, and a 45° an- to supinate the foot at the subtalar and trans- gle of skin entry aimed toward the tibia to avoid verse tarsal joints. Type 1 (slow-twitch) fibers the underlying anterior tibial artery and vein and predominate in this muscle. SYMPTOMS the deep peroneal nerve. A local twitch re- caused by TrPs in the tibialis anterior muscle in- sponse is often observed when the needle pen- clude referred pain and tenderness in the ankle etrates a TrP in this muscle. Application of inter- anteromedially and in the big toe, painful motion mittent cold with stretch of the muscle after in- of the ankle, dragging of the toes or ankle weak- jection, followed by moist heat, helps ensure ness, and tripping or falling when walking be- inactivation of any residual TrPs. Active range of cause of the weak dorsiflexion. The referred motion follows in order to restore normal func- pain pattern of the tibialis anterior may resemble tion of the muscle. CORRECTIVE ACTIONS to the patterns of the extensor hallucis longus and prevent reactivation of the TrPs in this muscle the other two anterior compartment muscles, but include a home self-stretch exercise program can be distinguished from them. Symptoms of and elimination of prolonged shortening of the an anterior compartment syndrome must be rec- muscle, for instance, by leveling an acutely up- ognized and should not be dismissed as ward-angled accelerator pedal of a car. In addi- myofascial pain. ACTIVATION OF TRIGGER tion, cruise control permits periodic relief to POINTS usually results from major overload of avoid a fixed position of the lower limb for an ex- the muscle or from an accident that causes ad- tended time. Release of antagonist tight calf ditional skeletal injury. On PATIENT EXAMINA- musculature helps restore balance and reduce TION, the clinician usually finds a tendency for overload of anterior compartment muscles. foot slap and foot drop during ambulation, deep 355

356 Part 3 / Leg, Ankle, and Foot Pain dorsal region of the great toe,49 or to the lower leg, ankle, and foot (or specifically the dorsal surface of the great toe).7,90 Tibialis anterior TrPs are occasionally the source of the chief pain complaint in children. The referred pain pattern is sim- ilar to that seen in adults.14 Gutstein42 described a patient with severe burn- ing pain in the foot and knee, especially after long periods of standing. He attributed the pain to my- algic spots along the lower half of the tibialis ante- rior muscle. Treatment with heat followed by firm local massage at the myalgic spots relieved the pain. In 14 subjects, Kellgren52 injected the proximal and middle parts of the belly of the tibialis ante- rior muscle with 0.1 mL of hypertonic saline solu- tion. The injection produced referred pain to the front of the ankle and in the outer and middle part of the front of the leg in most subjects. A few sub- jects had pain only at the ankle and a few only in the leg. This is similar to the pattern of referred pain seen clinically in patients with tibialis ante- rior TrPs, except that Kellgren reported no pain over the great toe. Injection of 0.05 mL of the hy- pertonic saline solution into the tibialis anterior tendon caused diffuse pain in a small area on the medial aspect of the instep in all subjects.52 Figure 1 9 . 1 . Pain pattern (dark red) referred from a 2. ANATOMICAL ATTACHMENTS AND trigger point (X) at its usual location in the right tibialis CONSIDERATIONS anterior muscle (light red), as s e e n in the anterior view (Figs. 19.2 and 19.3) with the foot slightly abducted. The essential pain pat- tern is solid red; the red stippling indicates occasional The tibialis anterior muscle is subcutane- spillover extension of the essential pattern. ous just lateral to the anterior sharp edge of the tibia (the shin) and becomes tendi- 1. REFERRED PAIN nous in the lower third of the leg (Fig. (Fig. 19.1) 19.2). It anchors proximally to the lateral condyle and upper half or two-thirds of Myofascial trigger points (TrPs) in the the lateral surface of the tibia, the adja- tibialis anterior muscle refer pain and cent interosseous membrane, the deep tenderness primarily to the anteromedial surface of the crural fascia, and the in- aspect of the ankle and over the dorsal termuscular septum common to the ex- and medial surfaces of the great toe (Fig. tensor digitorum longus.22 The muscle fi- 19.1).95 In addition, sometimes the pain bers of the tibialis anterior converge on (spillover pattern) may extend from the their aponeurosis and tendon to form a TrP downward over the shin to the ankle pennate structure.9 The tendon crosses in and foot anteromedially.86,87,96 The TrPs front of the tibia to the medial side of the usually occur in the upper third of the foot where it attaches distally to the me- muscle (Fig. 19.1). dial and plantar surfaces of the medial cu- neiform bone and to the base of the first Other authors reported that tibialis an- metatarsal medially.9,22 Accessory attach- terior TrPs referred pain to the anterior ments in the foot occurred in 2 1 . 7 % of 64 leg and dorsal ankle,88-90 dorsal ankle and human cadaver legs.58

Chapter 19 / Tibialis Anterior Muscle 357 Lateral condyle Patella Figure 19.2. Attachments of the right of tibia Tibial tuberosity tibialis anterior muscle (red), anterior Fibula view. The foot is turned outward to show the distal attachments to the medial cu- Tibialis anterior neiform and first metatarsal bones. The cross section indicated on this figure is Extensor shown in Figure 19.3. retinaculum Level of Cuboid cross section Tibia Calcaneus Talus Navicular Medial cuneiform 1 st metatarsal A cross section at the lower part of the diffusely distributed with the greatest concentra- middle third of the leg (Fig. 19.3) shows tion found toward the periphery and toward the that the tibialis anterior muscle occupies proximal end of the muscle.6 A similar location of a triangular space bounded by the tibia endplates around the periphery of this pennate medially, by only skin and crural fascia muscle appeared in the muscles of a stillborn in- anteriorly, and by the extensor hallucis fant.18 The tibialis anterior has fibers of intermedi- longus muscle laterally. These structural ate length, 8.7 cm. This length is similar to that of relations continue throughout the length fibers in the extensor hallucis longus and extensor of the muscle belly of the tibialis anterior. digitorum longus muscles.98 The deep peroneal nerve and anterior tib- ial vessels lie on the interosseus mem- Supplemental References brane deep to the muscle.17 The tibialis anterior muscle appears in front view Unyielding fascial structures and bone without nerves or vessels35,72,83 and in relation to that form the anterior compartment sur- the anterior tibial artery and vein and deep pero- round the tibialis anterior muscle. This neal nerve.4,32,73 The view from the medial side muscle shares this compartment with the shows the course of its tendon33 and the view extensor digitorum longus, extensor hal- from the lateral side demonstrates its close rela- lucis longus, and the peroneus tertius mus- tion to the extensor digitorum longus mus- cles, and with the deep peroneal nerve and c l e .3 4 , 6 3 , 8 2 the anterior tibial artery and vein.71 Markings on the bones locate the muscle's at- The myoneural endplates in whole tibialis ante- tachments to the tibia and to the medial cunei- form and first metatarsal bones of the foot.1,36,62,74 rior muscles of three adult human subjects were

358 Part 3 / Leg, Ankle, and Foot Pain Deep peroneal nerve and anterior tibial vessels Tibialis anterior Extensor hallucis longus Tibia Extensor digitorum longus and peroneus tertius Interosseous membrane Tibialis posterior Superificial peroneal nerve Flexor digitorum longus Peroneus brevis Tibial nerve and Peroneus longus posterior tibial vessels Fibula Plantaris tendon Gastrocnemius Flexor hallucis aponeurosis longus Peroneal vessels Intermuscular septum Soleus Figure 19.3. Cross section through the lower part of cross section, below the gastrocnemius muscle belly, the middle third of the right leg, viewed from above. is shown in Figure 19.2. (After Figure 4-72 in Grant's Major blood vessels and the tibialis anterior muscle Atlas of Anatomy.3) are dark red; other muscles are light red. Level of the A photograph reveals details of its tendinous at- 4. FUNCTION tachments in the foot.5 The tibialis anterior muscle helps main- Cross sections portray the relation of the tibialis tain standing balance through lengthen- anterior muscle to surrounding structures and its ing contractions to control excessive accessibility for injection: throughout its length in sway posteriorly, and through shorten- 13 serial cross sections,17 in three cross sections of ing contractions as needed to pull the the upper, middle, and lower thirds of the leg,37 in leg and body forward over the fixed two cross sections of the upper and lower thirds foot. It functions to prevent foot slap of the leg,20 in one cross section just above the following heel-strike and helps the foot middle of the leg,71 and one at the lower part of clear the ground during the swing phase the middle third of the leg.3 of gait. Loss of foot clearance greatly in- creases \"balance problems\" and the Photographs of well-muscled subjects illustrate danger of falling (a common hazard in surface contours produced by the tibialis anterior the elderly). During jogging and run- muscle.2,21,31,57 ning, electromyographic (EMG) activity begins just after toe-off and continues 3. INNERVATION through the first half of the support (stance) phase. This muscle is moder- The deep peroneal nerve supplies the tibialis anterior muscle with fibers from the fourth and fifth lumbar and the first sacral spinal nerves.22

ately to vigorously active during most Chapter 19 / Tibialis Anterior Muscle 359 sports activities. Its type 1 (slow-twitch) fibers predominate; type 2 (fast-twitch) Squatting with the heels flat on the floor caused fibers compose, at most, only one-third the tibialis anterior to produce 6 0 % of its maxi- of the muscle. mum voluntary contraction level of EMG activ- ity.76 The tibialis anterior muscle dorsiflexes and supinates (inverts and adducts) the Ambulation foot when the distal segment is free. How- ever, it does not contribute to inversion During walking, EMG activity in the tibialis ante- when the foot is plantar flexed. rior muscle reaches its primary peak at heel-strike and a secondary peak at toe-off. Paralysis of this Actions muscle results in foot-drop11,80 and a tendency to stub the toes on curbs or steps.80 In the non-weight-bearing limb, the tibialis an- terior muscle dorsiflexes the foot at the More specifically, the ankle dorsiflexors (tibi- talocrural joint and supinates (inverts and ad- alis anterior and long extensors of the toes) pre- ducts) the foot at the subtalar and transverse vent foot slap just after heel-strike; they undergo a tarsal joints;12,22 it is not active as an invertor lengthening contraction as they control the de- during plantar flexion.80 scent of the foot to the floor, or as they decelerate the foot at heel-strike.79 Foot clearance (or toe Direct electrical stimulation of the tibialis ante- clearance) during the swing phase requires a com- rior muscle first produces vigorous dorsiflexion bination of hip flexion, knee flexion, and ankle and then weak adduction26 of the foot. Stimula- dorsiflexion. tion specifically elevates the head of the first met- atarsal bone.27 Dragging of the toes at the b e g i n n i n g of s w i n g phase is due to inadequate hip and knee flex- Functions ion; later in swing, as the limb moves forward, toe dragging results from inadequate dorsiflex- Standing and Postural Changes ion.79 In normal subjects standing at ease, primarily the The primary peak of EMG activity in this soleus muscle made minor forward balance ad- muscle occurs at heel-strike11,40,94 at all speeds justments.10 In more than one-quarter of these nor- of ambulation.101 During the 100 milliseconds mal barefooted subjects, the tibialis anterior re- around heel-strike, this activity averages 44% mained silent. The EMG activity observed in some of a maximum voluntary contraction.50 During subjects disappeared when the subject leaned for- full-foot contact at midstance phase, a brief pe- ward. Tibialis anterior motor unit activity devel- riod of no EMG activity occurs.11,64 The second- oped or increased when the subject leaned back- ary peak during walking appears at toe-off (end ward,10 as the muscle helps control this move- of stance phase)11,94 at all speeds.101 The contin- ment. uation of EMG activity in this muscle through- out swing phase is variable from person to per- The tibialis anterior became active when sub- son. In various reports, it: (a) c o n t i n u e d jects leaned backward, and activity ceased when throughout swing p h a s e ; 9 4 (b) c o n t i n u e d in four they leaned forward, at any rate of movement.39,75 of seven subjects and was biphasic in the other It became active in response to equivalent sepa- three at all s p e e d s ; 7 0 (c) faded out during m o s t rate or combined bilateral limb displacements of the swing p h a s e ; 1 1 and (d) r e a c h e d zero ac- standing on a double treadmill,25 when combined tivity at some point during swing phase in six with other variations of standing posture,76 when of six subjects at a wide range of walking thrown off balance by voluntary, rapid arm speeds.84 pushes or pulls against a fixed resistance,23 or when standing on an oscillating platform.24 The The tibialis anterior muscle does not con- further a subject leaned back and the closer the tribute significantlyto arch support of t h e nor- center of pressure moved toward the heel, the mal foot during weight bearing.11,13 However, greater became the EMG activity of the tibialis an- the tibialis anterior of standing subjects terior.77 showed greater EMG activity in those subjects who had flat feet.41

360 Part 3 / Leg, Ankle, and Foot Pain Increasing the thickness of heel lifts in men in- anterior exhibited at least moderate EMG activ- creased tibialis anterior EMG activity during ity, and frequently, this was as vigorous as for walking.55 The opposite effect occurred in women, any of the other muscles monitored.16 presumably because they had accommodated to high heels; for them, the unaccustomed flatness of Fiber Types the lowest heel lifts stimulated activity in this muscle.56 Henriksson-Larsen and associates47 determined the fiber type distribution in a 1-mm2 area ev- W h e n subjects descended stairs, EMG activity in ery 9 mm throughout whole-muscle cross sec- the tibialis anterior muscle showed a similar pat- tions of the tibialis anterior muscles from six tern to that seen during ambulation. Activity oc- young previously healthy adult males who suf- curred around the beginning and end of stance fered sudden accidental death. Type 1 (slow- phase, but in one-third of subjects, the tibialis an- twitch) fibers predominated and type 2 (fast- terior was continuously active throughout the cy- twitch) fibers were NOT randomly distributed. cle.93 When ascending stairs, EMG activity began A gradual, often dramatic, relative increase in near the end of stance and continued throughout type 2 fibers was seen from the surface of the most of swing phase. This activity apparently muscle toward the deeper regions, where the serves to ensure foot clearance on its way up to number of type 2 fibers was approximately the next step.93 twice that near the surface. In addition, two or more major foci with a comparatively high den- Athletic Activities sity of type 2 fibers were sometimes present. Within a distance of only 10 mm, the propor- The pattern of EMG activity of the tibialis ante- tion of type 2 fibers could vary 20%. The aver- rior m u s c l e changes between jogging, running, age value for all samples in one muscle varied and sprinting. During jogging and running, activ- from 1 9 - 3 3 % for type 2 fibers among the six ity is absent at toe-off but appears shortly tibialis anterior muscles and the mean for the thereafter and continues throughout the re- group was 2 8 % of type 2 fibers.47 Similar re- mainder of the swing phase and the first half of sults were observed in female anterior tibialis the support phase. During swing phase, contin- muscles.45 ued activity of the muscle ensures dorsiflexion of the foot. However, during sprinting, EMG ac- Sandstedt85 found that the proportion of type 2 tivity ceases briefly at midswing when plantar fibers could vary from 7-30% in two biopsies flexion of the foot begins.59 from the same muscle. These studies emphasize the large sampling errors inherent in a single W h e n the subject does a two-leg jump upward, small-sample biopsy of this muscle. Both type 1 EMG activity in the tibialis anterior muscle be- and type 2 fibers that lie deep in this muscle have gins as the foot clears the ground. Activity larger diameters than those that lie in superficial ceases before the subject reaches the highest areas.46 point in the jump. Vigorous EMG activity re- turns before landing and continues at reduced Other authors who took small,, superficial intensity during the landing itself and into the samples of the tibialis anterior muscle found stabilization phase.51 that it averaged 22% type 2 fibers among 29 healthy volunteers84 and 77% type 1 fibers (less During ergometer cycling, this m u s c l e gener- than 23% type 2 fibers) among seven normal ated EMG activity that corresponded to only male subjects.44 9% of its maximum voluntary contraction as the pedal was passing its highest position. At 5. FUNCTIONAL (MYOTATIC) UNIT this time, the ankle joint is in its most dor- siflexed position.28 Dorsiflexion of the foot can occur as a bal- anced action of two dorsiflexors: the tibi- Broer and Houtz16 measured the EMG activity alis anterior, which also inverts, and the of the tibialis anterior m u s c l e during 13 right- extensor digitorum longus, which also handed sports activities. T h e activities i n c l u d e d everts the foot.27 The third primary dor- overhand throws, underhand throws, tennis siflexor is the peroneus tertius. These and golf swings, hitting a baseball, and single- dorsiflexors are assisted by the extensor foot jumps. The EMG activity in the right tibi- hallucis longus.80 The chief antagonists to alis anterior muscle was equal to or greater dorsiflexion are the gastrocnemius and than that of the left in every activity except the soleus muscles, assisted by the peroneus single-foot jump volleyball spike. In every right-handed sport activity, the right tibialis

Chapter 19 / Tibialis Anterior Muscle 361 longus and brevis, long flexors of the toes, the tibialis anterior, but not the toe pain. and the tibialis posterior muscle.80 Pain referred from flexor hallucis longus TrPs (see Fig. 25.1) appears on the plan- 6. SYMPTOMS tar, not the dorsal, surface of the great toe without spillover pain to the ankle. First The chief complaint of patients with ac- dorsal interosseous TrPs refer pain (see tive TrPs in the tibialis anterior is usually Fig. 27.3) primarily to the second toe with pain on the anteromedial aspect of the an- spillover pain to the space between the kle and in the big toe. Other complaints first and second metatarsals, on the dor- may include: weakness of dorsiflexion sum of the foot lateral to the pain pattern when walking, falling, dragging of the due to tibialis anterior TrPs. foot that causes tripping, and general weakness of the ankle. Painful motion of To distinguish myofascial referred pain the ankle may bother the patient in the from painful fascial and articular struc- absence of any evidence of joint injury.95 tures in the ankle and foot, the examiner Loss of function is especially evident palpates: associated muscles for taut when TrPs in the long extensor muscles bands and for TrP tenderness with in- of the toes cause additional dorsiflexion duced referral of pain, the joints for ten- weakness. derness and restricted range of motion, and the ligaments for tenderness. Re- Usually, patients with tibialis anterior ferred pain and tenderness of tibialis an- TrPs do not complain of nocturnal pain, terior TrPs can readily be mistaken for and a plantar flexed position of the ankle disease of the first metatarsophalangeal throughout the night does not bother this joint.81 muscle unless its TrPs are sufficiently ac- tive to cause some degree of constant re- Other conditions deserving differential ferred pain. consideration include L5 radiculopathy, anterior compartment syndrome, and her- The tibialis anterior myofascial pain niation of the tibialis anterior muscle. syndrome rarely presents alone as a sin- gle-muscle syndrome, but occurs in asso- Radiculopathy ciation with TrPs in other leg muscles. Preservation of the tendon reflex of the tibialis an- Differential Diagnosis terior muscle reduces the likelihood of an L5 ra- The pain referred from TrPs in several other leg and foot muscles can have a dicular compression as a contributing cause of the confusingly similar distribution to that of the tibialis anterior TrPs. The pain pat- patient's pain. This reflex91 was absent bilaterally tern of extensor hallucis longus TrPs (see Fig. 24.1), which is the most similar, ap- in 11%, and missing on only one side in an addi- pears on the dorsum of the foot in an area between the ankle and great toe, concen- tional 6%, of 70 healthy subjects. A hand-held re- trating over the first metatarsal head, not over the great toe. However, the extensor flex hammer elicited the reflex response and sur- hallucis longus may refer spillover pain to the anteromedial ankle and to the dor- face electrodes recorded it electromyographically. sum of the great toe. The TrPs of the ex- tensor digitorum longus (see Fig. 24.1) However, the reflex was absent on only the af- and of the extensor digitorum brevis and the extensor hallucis brevis (see Fig. fected side in 72% of 18 patients with L5 radicular 26.1) also refer pain to the middorsum of the foot, but more laterally over the long compression.91 Electrodiagnostic testing is indi- extensor tendons of the lesser toes. In ad- dition, the extensor digitorum longus cated if a serious question of radiculopathy re- may refer spillover pain up to the antero- lateral ankle and down to the four lesser mains. toes. The pain from peroneus tertius TrPs (see Fig. 20.1B) mimics the ankle pain of Anterior Compartment Syndrome Compartment syndromes are characterized by in- creased pressure within a muscular compartment sufficient to compromise the circulation of the muscles within it. A compartment space is deter- mined anatomically by an unyielding fascial (and bony) enclosure of the muscles. Four compart- ments are recognized in the leg: (a) the anterior compartment includes the tibialis anterior, exten- sor hallucis longus, extensor digitorum longus, and peroneus tertius. (b) T h e deep posterior c o m - partment comprises the antagonists to the muscles of the anterior compartment: the tibialis posterior, flexor hallucis longus, and flexor digitorum

362 Part 3 / Leg, Ankle, and Foot Pain scarred, hypersensitive, poorly vascularized tis- sues. Owen and associates studied certain pos- longus. (c) T h e superficial posterior compartment tures that are commonly assumed during drug is usually defined as including both the soleus overdose (the squat and knee-chest positions); and gastrocnemius muscles,100 but the soleus is when these postures were tested in 17 normal vol- more vulnerable to developing a compartment unteers, anterior compartment pressures in the syndrome, (d) T h e lateral compartment encom- range of 49-100 mm Hg were produced.78 passes the peroneus longus and brevis muscles. Anterior compartment syndromes are recognized Tight, shortened calf muscles overload weak- more commonly than are posterior compartment ened anterior compartment muscles and predis- syndromes.100 Consideration of the posterior com- pose the athlete to developing an anterior com- partment syndrome appears on pages 443—444 of partment syndrome.85 this volume. The definitive diagnostic test for an anterior If the patient's leg pain is caused by an anterior compartment syndrome is measurement of intra- compartment syndrome, it is most important that muscular pressure within the anterior compart- this condition be recognized immediately and ment. Three techniques are in common use and managed properly to avoid possibly catastrophic are graphically summarized.48 The Whitesides consequences. Diffuse tightness and tenderness technique99 employs a mercury manometer and over the entire belly of the tibialis anterior sug- needle, which are readily available in any emer- gests an anterior compartment syndrome. gency room, but are less accurate than a wick catheter. The wick catheter technique of Mubarak The anterior (tibial) compartment syndrome is and associates68 uses a fiber-filled polyethylene also sometimes called anterior shin splints, a catheter inserted into the compartment and at- term that is properly used to describe periosteal tached to a pressure transducer. It is resistant to irritation from overuse. A compartment syndrome blockage. The continuous infusion technique of should be distinguished from shin splints. Shin Matsen60 substitutes a low-rate infusion pump for splints are discussed on pages 443—444 of this vol- a wick to maintain patency of the monitoring nee- ume. The compartment syndrome arises because dle; using this method, the pressure can be moni- of increased pressure within the unyielding ante- tored continuously for 3 days. Sustained pres- rior compartment of the leg. The pressure ob- sures in excess of 30 mm Hg69 or 40-50 mm Hg60 structs venous outflow, which causes further have been considered the indication for extensive swelling and more pressure. The resultant ische- fasciotomy of the compartment. mia leads to necrosis of the muscles and nerves within the compartment. The process can begin In acute cases, a brief period of rest and cryo- with swelling of the tibialis anterior, extensor hal- therapy to reduce pain, swelling, and metabolic lucis longus, extensor digitorum longus, and/or demand can be tried only with close monitoring the peroneus tertius muscles in response to strong before more drastic measures are considered. eccentric contractions sufficient to produce post- exercise soreness.38 Patients with the anterior Elevation of the leg is contraindicated because compartment syndrome exhibit pain, paresthe- it has been shown to reduce oxygen tension sias, and tenderness both in the ischemic muscles within the compartment.61 and in the region supplied by the deep peroneal nerve. The muscles are sensitive to passive Among runners, anterior shin splints (periosteal stretch, and active contraction of the muscles in- irritation) may develop when the athlete changes creases symptoms. Among athletes, symptoms from a flatfooted to a toe-running style, begins may develop progressively over a period of training on a track or hill [especially downhill time.48,66,67 Rarely, an anterior tibial compartment running], or runs in a shoe with a sole that is too syndrome may present as a painless weakness of flexible.15 A too-rigid shoe can also cause shin dorsiflexion. The lack of pain has been attributed splints. The activities listed previously may also to pressure-induced neurapraxia.19 overload the tibialis anterior muscle and activate TrPs in it. Patients for whom surgical release of pressure is too late, and who have postnecrotic scarring of the Herniation muscles and nerves within the compartment, are prone also to develop active TrPs in muscles Subcutaneous herniation of the tibialis anterior within the compartment. These TrPs add to the muscle through its investing fascia may be painful pain of direct neurological origin. Massage is of- during standing and walking or it may be of cos- ten poorly tolerated because of residual allodynia metic concern.43 Magnetic resonance imaging, un- and hyperesthesia. Injection of any space-occupy- like computed tomography, unequivocally identi- ing substance may also be poorly tolerated by the fies the extent of fascial splitting and the size of

Chapter 19 / Tibialis Anterior Muscle 363 muscle herniation because it distinguishes more motion because of pain and muscle tight- clearly between these two soft-tissue structures.102 ness. 7. ACTIVATION AND PERPETUATION Deep tenderness over the ankle and OF TRIGGER POINTS great toe may be referred from TrPs of the tibialis anterior muscle.95 Trigger points in the tibialis anterior mus- 9. TRIGGER POINT EXAMINATION cle may be activated by the same forces (Fig. 19.4) that cause an ankle sprain or fracture, and by overload sufficient to induce an ante- To find tibialis anterior TrPs in the su- rior compartment syndrome. The TrPs of pine patient, the examiner first locates this muscle seem more likely to be the re- the sharp edge of the tibia at approxi- sult of serious gross trauma than due sim- mately the junction of the proximal and ply to overuse (repetitive, micromechani- middle thirds of the leg. Flat palpation cal trauma). Walking on rough ground or reveals taut bands and TrP spot tender- on a slanted surface, however, can precip- ness in the muscle mass lateral to the itate myofascial problems. tibia (Fig. 19.4). The taut bands in this muscle are parallel to the tibia. Snapping A motor vehicle accident did not acti- transverse palpation at the TrP in the taut vate TrPs in the tibialis anterior muscle in band evokes a vigorous and highly visible any of the 100 patients examined, al- twitch response in this muscle. This re- though other lower limb muscles were sponse appears as transient inversion and commonly involved.8 Such an accident is dorsiflexion of the foot if the foot is free to unlikely to cause a forceful lengthening move (Fig. 19.4). Digital pressure applied contraction of this muscle. to an active TrP will usually evoke or in- tensify the spontaneous pain referred to Catching the toe on an obstruction dur- the ankle95 and foot. ing early swing phase (tripping or stum- bling during the contraction phase of the Sola89 observed that the TrPs were most tibialis anterior) can cause eccentric con- commonly located in the upper one-third traction overload that activates or per- of this muscle, as we have found. Lange54 petuates TrPs in the muscle. The overload pictured myogelosis (tender taut bands is aggravated by a proportional increase [of TrPs]) as running vertically through in the reflex response to sudden stretch, a the midportion of the muscle belly. response that ranges from 0-40% of maxi- mum voluntary contraction.92 8. PATIENT EXAMINATION 10. ENTRAPMENTS The clinician observes the patient for foot To our knowledge, TrPs in this muscle do slap and foot-drop during ambulation. not cause nerve entrapment; however, Foot slap occurs when the forefoot slaps tibialis anterior TrPs are a likely sequela to the floor immediately following heel- to an anterior compartment syndrome. strike. Foot-drop is a failure to dorsiflex the foot sufficiently to provide adequate 11. ASSOCIATED TRIGGER POINTS clearance between the toes and the floor, particularly during late swing. The peroneus longus and tibialis anterior muscles often become involved together; Active TrPs in this muscle cause some they operate as a pair of well-matched an- degree of weakness. This weakness is eas- tagonists for stabilization and balance of ily masked by compensatory contraction the foot. The extensor hallucis longus of the long extensor muscles of the toes or and, to a lesser degree, the extensor dig- the peroneus tertius muscle. To test the itorum longus may also develop TrPs as tibialis anterior muscle for strength, the agonists to the tibialis anterior muscle. seated patient first inverts and then dor- Tibialis posterior TrPs are not usually siflexes the foot against resistance with- identified as related to TrPs in the tibialis out extension of the great toe.53 anterior muscle. Active or latent TrPs in the tibialis an- terior muscle restrict the stretch range of

364 Part 3 / Leg, Ankle, and Foot Pain Figure 19.4. Palpation of trigger points in the right movement (inversion and dorsiflexion at the ankle) tibialis anterior muscle. The solid circle covers the that is characteristic of a strong local twitch response on snapping palpation at the trigger point. head of the fibula. Digital pressure is exerted toward the tibia. The dotted outline of the foot indicates the 12. INTERMITTENT COLD WITH that develops. To enhance release of tight STRETCH tibialis anterior fibers, the patient em- (Fig. 19.5) ploys postisometric relaxation by first slowly inhaling while gently contracting The technique for application of vapo- the tibialis anterior against resistance. coolant spray is discussed in Volume 1, The patient then exhales slowly while re- pages 6 7 - 6 4 . 9 7 Details for using ice as the laxing, during the application of the inter- vehicle for intermittent cold appear on mittent cold with passive elongation of page 9 in this volume, and reflex tech- the muscle by the operator. Stretch of this niques to augment relaxation and stretch muscle begins by placing the foot in the are described on pages 10-11. Avoid position of maximum available plantar stretching hypermobile joints in the foot flexion (Fig. 19.5A). Then, addition of and ankle to their full range. Alternative passive pronation of the foot further elon- treatment techniques are presented on gates the tibialis anterior (Fig. 19.5B). pages 9-11 of this volume. Gentle pressure sustained in this position helps take advantage of the slack that de- In preparation for the procedure of in- velops during the application of intermit- termittent cold with stretch, the patient tent cold combined with enhancement of lies supine with the foot of the involved relaxation. Several cycles of intermittent side over the end of the treatment table. A cold combined with postisometric relaxa- sheet or blanket covers the patient to en- tion usually suffice to lengthen the mus- sure comfort and to avoid body cooling. cle fully and to achieve as much range of The patient notes where passive plantar motion as will occur in this patient with flexion stops to mark the limit of its this technique. range. The initial application of parallel sweeps of ice or vapocoolant spray fol- The patient compares the new range of lows the thin arrows in Figure 19.5, down- motion to that noted before this proce- ward over the muscle and over the re- dure. The progress helps fix in the pa- ferred pain pattern.86,87 Gentle, steady tient's mind the critical importance of full pressure is applied to the foot to increase range of motion for relief of pain. It also plantar flexion and to take up any slack improves compliance with the home stretch program.

Chapter 19 / Tibialis Anterior Muscle 365 Figure 19.5. Stretch position and inter- mittent cold pattern (thin arrows) for trig- ger points in the right tibialis anterior muscle. The X marks the usual location of trigger points in this muscle. The solid semicircles cover the fibular head. The thick arrow indicates the direction of pressure that the operator exerts to stretch the muscle. A, icing or vapocool- ant spray pattern during initial stretch to plantar flex the foot. B. while continuing passive plantar flexion, the foot is also pronated (everted and abducted). Travell95 reported that applying sweeps the patient actively contracts the calf of spray just to the reference zone over muscles to assist plantar flexion and re- the ankle relieves the pain only momenta- ciprocally inhibit contraction of the tibi- rily. Applying the spray over the TrP and alis anterior. This supplemental effort by the entire muscle can abolish pain, re- the patient can be very effective for re- striction of motion, and deep tenderness leasing tension in the tibialis anterior in the reference zone for long periods of muscle. time. Using implanted fine-wire electrodes, Etnyre Following the therapy described previ- and Abraham29 showed the error of previous EMG ously, a moist, wet-proof heating pad ap- studies that reported spontaneous co-contraction plied promptly for several minutes of the tibialis anterior while being stretched dur- rewarms the skin. Several cycles of full ing antagonist muscle activation. The surface elec- active range of motion (movement from trodes previously used detected volume-con- full plantar flexion to full dorsiflexion) ducted \"cross talk\" from the tibialis anterior and complete the procedure. Following dem- not co-contraction activity. This later study onstration and written instructions, the removes any theoretical objection to this useful patient should then practice the home ex- supplemental relaxation technique. ercise program described in Section 14, Corrective Exercise. The TrPs in the tibialis anterior muscle are usually sufficiently superficial to re- To stretch this muscle in the supine pa- spond well to slow, deep, stripping mas- tient, Evjenth and Hamberg30 support the sage. bent knee with a pillow and add a pad be- neath the leg while applying passive plantar flexion to the foot. Meanwhile,

366 Part 3 / Leg, Ankle, and Foot Pain Figure 19.6. Injection of a trigger point in the right tibialis anterior muscle. The solid circle marks the head of the fibula. A pad that slightly flexes the knee makes the patient more comfortable. 13. INJECTION AND STRETCH TrPs in that region should be ensured by (Fig. 19.6) probing exploration with the needle and injection of TrPs until all local tenderness The principles for injecting TrPs are pre- disappears. However, after injection, sev- sented in detail on pages 74-86 of Vol- eral sweeps of cold applied during passive ume l.97 stretch of the muscle help inactivate any remaining TrPs. The patient lies supine with the knee of the affected limb resting on a pad to flex it Prompt application of moist heat for slightly and to make the patient more several minutes reduces postinjection comfortable. Section 9 of this chapter de- soreness and enhances the effect of sev- scribes how to locate the taut bands in eral cycles of active range of motion to this muscle. The TrP is that spot along the help restore muscle \"memory\" and nor- band which shows the greatest tender- mal function. ness, the largest local twitch response, and from which the most intense pain is Before leaving the office, the patient referred in response to the least pressure. practices the home exercise program as Precise injection of the TrP is illustrated presented in the next section. in Figure 19.6. Ten milliliters of 0.5% procaine solution are used to fill a syringe 14. CORRECTIVE ACTIONS to which a 21-gauge, 38-mm (l1/2-in) nee- dle has been attached. A major source of overload of the tibialis anterior muscle can be tension of the calf In many patients, this length of needle musculature. In that situation, an essen- can reach to the anterior tibial artery and tial first step of tibialis anterior therapy is vein and deep peroneal nerve if the needle to release the calf muscle tightness and is pointed straight down through the full inactivate any responsible TrPs. depth of the muscle close to the tibia.71 For this reason, the clinician should direct the If the anterior compartment muscles are needle toward the tibia at a 45° angle to weak, a strengthening program for the the skin to avoid the possibility of hitting dorsiflexors of the foot is in order to re- neurovascular structures. During injection, store muscular balance at the ankle. cutaneous and deep hemostasis should be supplied by spreading finger pressure Corrective Body Mechanics against the skin astride the needle. A jump response of the patient and a local twitch The postural distortion caused by a Mor- response of the muscle usually accompany ton foot structure should be corrected, as penetration of one of these TrPs by the described in Chapter 20, to normalize foot needle. Inactivation of the entire cluster of mechanics and muscle balance at the an- kle.

Chapter 19 / Tibialis Anterior Muscle 367 Corrective Posture and Activities as well as the soleus muscle and usually provides welcome relief. Some automobile accelerator pedals are steeply angled and cause sustained short- References ening of the tibialis anterior. A block under the driver's heel reduces the exces- 1. Anderson JE: Grant's Atlas of Anatomy, Ed. 8. sive dorsiflexion. Use of a cruise control Williams & Wilkins, Baltimore, 1983 (Figs. 4- provides the opportunity for the driver to 70B, 4-103, 4-107). change foot position and obtain periodic relief from immobility. 2. Ibid. (Fig. 4 - 7 1 C ) . 3. Ibid. (Fig. 4 - 7 2 ) . The individual is encouraged to walk 4. Ibid. (Fig. 4 - 7 3 ) . on smooth surfaces instead of uneven 5. Ibid. (Figs. 4 - 9 8 , 4 - 1 1 7 ) . ground, e.g., to walk on a smooth path- 6. Aquilonius S-M, Askmark H, Gillberg P-G, et way instead of a sidewalk with uneven bricks or cracks. In addition, a surface al.: Topographical localization of motor end- should be selected that is level from side plates in cryosections of whole human mus- to side and not tilted laterally, as is the cles. Muscle Nerve 7 : 2 8 7 - 2 9 3 , 1 9 8 4 . edge of a crowned road or a slanted beach. 7. Arcangeli P, Digiesi V, Ronchi O, Dorigo B, Bartoli V: Mechanisms of ischemic pain in pe- In general, the leg muscles feel better if ripheral occlusive arterial disease. In Advances the ankle is maintained in a neutral posi- in Pain Research and Therapy, edited by J. J. tion throughout the night. This position is Bonica and D. Albe-Fessard, Vol. 1. Raven facilitated by use of a foot-bracing pillow Press, New York, 1976 (pp. 965-973). as described and illustrated in Figure 21.11 of Chapter 21. 8. Baker BA: The muscle trigger: evidence of overload injury. J Neurol Orthop Med Surg 7 : 3 5 - Home Therapeutic Program 44, 1986. The patient should stretch the tibialis an- 9. Bardeen CR: T h e musculature, Sect. 5. In Mor- terior at home one to three times daily. ris's Human Anatomy, edited by C. M. Jackson, Good control may be exerted in the sitting Ed. 6. Blakiston's Son & Co., Philadelphia, position by crossing the involved foot 1921 (pp. 512, 515-516). over the other thigh and using the hands to plantar flex and evert the foot pas- 10. Basmajian JV, Deluca CJ: Muscles Alive, Ed. 5. sively. An alternative stretch is with the Williams & Wilkins, Baltimore, 1985 (pp. 2 5 6 - patient sitting forward on a chair so that 257). the foot of the leg to be stretched reaches back under the chair with the dorsal sur- 1 1 . Ibid. (pp. 3 7 4 - 3 7 7 ) . face of the toes and metatarsal heads sol- 12. Basmajian JV, Slonecker CE: Grant's Method of idly on the floor, placing the foot in plan- tar flexion. The patient presses the dor- Anatomy. A Clinical Problem-Solving Approach, sum of the foot against the floor to further plantar flex and slightly evert the ankle. Ed. 11. Williams & Wilkins, Baltimore, 1989 He or she learns to adjust the degree of (p. 332). foot eversion to optimize the feeling of tension on the tight tibialis anterior mus- 13. Basmajian JV, Stecko G: The role of muscles in cle. arch support of the foot. An electromyographic study. J Bone Joint Surg [Am] 4 5 : 1 1 8 4 - 1 1 9 0 , Incorporating the principles of post- 1963. isometric relaxation (see Chapter 2, pages 10-11) while performing the stretch 14. Bates T, Grunwaldt E: Myofascial pain in markedly improves its effectiveness. Ad- childhood. J Pediatr 5 3 : 1 9 8 - 2 0 9 , 1 9 5 8 . dition of calf contraction to enhance plan- tar flexion during the stretch phase (re- 15. Brody DM: Running injuries. Clinical Symposia ciprocal inhibition) can also be helpful. 3 2 : 1 - 3 6 , 1 9 8 0 (see pp. 1 9 , 20). When a person is seated for a prolonged 16. Broer MR, Houtz SJ: Patterns of Muscular Activity period of time, the Pedal Exercise (see in Selected Sports Skills. Charles C T h o m a s , Fig. 22.13) stretches the tibialis anterior Springfield, 1967. 17. Carter BL, Morehead J, Wolpert S M , et al.: Cross-Sectional Anatomy. Appleton-Century- Crofts, New York, 1977 (Sects. 72-84). 18. Christensen E: Topography of terminal motor innervation in striated muscles from stillborn infants. Am J Phys Med 3 8 : 6 5 - 7 8 , 1 9 5 9 . 19. Ciacci G, Federico A, Giannini F, et al.: Exer- cise-induced bilateral anterior tibial compart- ment syndrome without pain. Ital J Neurol Sci 7: 377-380, 1986. 2 0 . Clemente CD: Gray's Anatomy of the Human Body, American Ed. 3 0 . Lea & Febiger, Phila- delphia, 1985 (p. 111). 2 1 . Ibid. (p. 1 1 2 ) . 2 2 . Ibid. (pp. 5 7 3 - 5 7 4 ) . 23. Cordo PJ, Nashner LM: Properties of postural adjustments associated with rapid arm move- ments. J Neurophysiol 4 7 : 2 8 7 - 3 0 2 , 1 9 8 2 . 24. Dickstein R, Pillar T, Hocherman S: The contri- bution of vision and of sidedness to responses

368 Part 3 / Leg, Ankle, and Foot Pain of the ankle musculature to continuous move- and analysis of cross-sections of whole tibialis ment of the base of support. Int J Neurosci 40: anterior. Histochem J 7 5 : 1 6 7 - 1 7 8 , 1 9 8 3 . 101-108, 1988. 48. Henstorf JE, Olson S: Compartment syndrome: 25. Dietz V, Horstmann GA, Berger W: Interlimb pathophysiology, diagnosis, and treatment. Surg Rounds Orthop-.pp. 33-41, Feb. 1987. coordination of leg-muscle activation during perturbation of stance in humans. J Neuro- 49. Jacobsen S: Myofascielt smertesyndrom (Myo- physiol 6 2 : 6 8 0 - 6 9 3 , 1 9 8 9 . fascial pain syndrome). Ugeskr Laeger 7 4 9 : 6 0 0 - 2 6 . Duchenne GB: Physiology of Motion, translated 601, 1987. by E.B. Kaplan. J. B. Lippincott, Philadelphia, 50. Jakobsson F, Borg K, Edstrom L, et al.: Use of 1949 (pp. 337-339). 27. Ibid. (pp. 3 4 1 - 3 4 4 ) . motor units in relation to muscle fiber type and size in man. Muscle Nerve 7 7 : 1 2 1 1 - 1 2 1 8 , 1 9 8 8 . 28. Ericson MO, Nisell R, Arborelius UP, et al.: 51. Kamon E: Electromyographic kinesiology of Muscular activity during ergometer cycling. jumping. Arch Phys Med Rehabil 5 2 : 1 5 2 - 1 5 7 , Scand J Rehabil Med 7 7 : 5 3 - 6 1 , 1 9 8 5 . 1971. 29. Etnyre BR, Abraham LD: Antagonist muscle ac- 52. Kellgren JH: Observations on referred pain tivity during stretching: a paradox re-assessed. arising from muscle. Clin Sci 3 : 1 7 5 - 1 9 0 , 1938 Med Sci Sports Exer 2 0 : 2 8 5 - 2 8 9 , 1 9 8 8 . 3 0 . Evjenth O, Hamberg J: Muscle Stretching in Man- (see pp. 177-178, Fig. 2). ual Therapy, A Clinical Manual. Alfta Rehab 5 3 . Kendall FP, McCreary EK: Muscles, Testing and F0rlag, Alfta, Sweden, 1984 (p. 135). Function, Ed. 3. Williams & Wilkins, Baltimore, 3 1 . Ferner H, Staubesand J: Sobotta Atlas of Human 1983 (p. 141). Anatomy, Ed. 10, Vol. 2. Urban & Schwarzen- 54. Lange M. Die Muskelharten (Myogelosen). J.F. berg, Baltimore, 1983 (Fig. 380). Lehmanns Verlag, Mvinchen, 1931. 3 2 . Ibid. 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M c M i n n RMH, Hutchings RT: Color Atlas of anterior tibialis muscle: case report and review Human Anatomy. Year Book Medical Publishers, of the literature. J Am Acad Dermatol 2 2 : 1 2 3 - Chicago, 1977 (pp. 281, 282, 289). 124, 1990. 6 3 . Ibid. (p. 3 1 2 ) . 44. Helliwell TR, Coakley J, Smith PEM, et al.: The 64. Milner M, Basmajian JV, Quanbury AO: Multi- morphology and morphometry of the normal factorial analysis of walking by electromy- human tibialis anterior muscle. Neuropathol ography and computer. Am J Phys Med 5 0 : 2 3 5 - Appl Neurobiol 1 3 : 2 9 7 - 3 0 7 , 1987. 258, 1971. 45. Henriksson-Larsen K: Distribution, number 65. Mirkin G: Keeping pace with new problems and size of different types of fibres in whole when your patients exercise. Mod Med NZ:pp. cross-sections of female m tibialis anterior. An 6-14, Dec. 1980. enzyme histochemical study. Acta Physiol Scand 7 2 3 : 2 2 9 - 2 3 5 , 1 9 8 5 . 66. Moore MP: Shin splints. Diagnosis, manage- ment, prevention. Postgrad Med 8 3 : 1 9 9 - 2 1 0 , 46. Henriksson-Larsen K, Friden J, Wretling ML: 1988. Distribution of fibre sizes in human skeletal 67. Moretz WH: The anterior compartment (ante- muscle. An enzyme histochemical study in m rior tibial) ischemia syndrome. Am Surg 19: tibialis anterior. Acta Physiol Scand 7 2 3 : 1 7 1 - 728-749, 1953. 177, 1985. 68. Mubarak SJ, Hargens AR, Owen CA, et al.: The 47. Henriksson-Larsen KB, Lexell J, Sjostrom M: wick catheter technique for measurement of in- Distribution of different fibre types in human tramuscular pressure. J Bone Joint Surg [Am] 58: skeletal muscles. I. Method for the preparation 1016-1020, 1976. 69. Mubarak SJ, Owen CA, Hargens AR, et al.: Acute compartment syndromes: diagnosis and

Chapter 19 / Tibialis Anterior Muscle 369 treatment with the aid of the wick catheter. J 88. Sola AE: Treatment of myofascial pain syn- Bone Joint Surg [Am] 6 0 : 1 0 9 1 - 1 0 9 5 , 1978. dromes. In Recent Advances in the Management 70. Murray MP, Mollinger LA, Gardner GM, et al.: of Pain, edited by C. Benedetti, C. R. Chapman, Kinematic and EMG patterns during slow, free, G. Moricca. Raven Press, New York, 1984, Se- and fast walking. J Orthop Res 2 : 2 7 2 - 2 8 0 , 1 9 8 4 . ries title: Advances in Pain Research and Ther- 7 1 . Netter FH: The Ciba Collection of Medical Illustra- apy, Vol. 7 (pp. 4 6 7 - 4 8 5 , see p. 4 8 1 ) . tions, Vol. 8, Musculoskeletal System. Part I: 89. Sola AE: Trigger point therapy, Chapter 47. In Anatomy, Physiology and Metabolic Disorders. Clinical Procedures in Emergency Medicine, ed- Ciba-Geigy Corporation, Summit, 1987 (p. 98). ited by J.R. Roberts and J.R. Hedges. W.B. 72. Ibid. (p. 99). 73. Ibid. (pp. 100, 104). Saunders, Philadelphia, 1985 (pp. 674-686, 74. Ibid. (p. 107). see p. 683, Fig. 47-14). 75. Oddsson L: Motor patterns of a fast voluntary 90. Sola AE, Williams RL: Myofascial pain syn- postural task in man: trunk extension in stand- dromes. Neurology 6 : 9 1 - 9 5 , 1 9 5 6 . ing. Acta Physiol Scand 1 3 6 : 4 7 - 5 8 , 1 9 8 9 . 91. Stam J: The tibialis anterior reflex in healthy 76. Okada M: An electromyographic estimation of subjects and in L5 radicular compression. J Neurol Neurosurg Psychiatry 5 7 : 3 9 7 - 4 0 2 , 1 9 8 8 . the relative muscular load in different human postures. J Human Ergol 1:75-93, 1 9 7 2 . 92. Toft E, Sinkjaer R, Andreassen S: Mechanical 77. Okada M, Fujiwara K: Muscle activity around and electromyographic responses to stretch of the ankle joint as correlated with the center of the human anterior tibial muscle at different foot pressure in an upright stance. In Bi- levels of contraction. Exp Brain Res 7 4 : 2 1 3 - 2 1 9 , omechanics 8A, M. Matsui, K. Kobayashi (eds). 1989. Human Kinetics Publ., Champaign, 1983 (pp. 93. Townsend MA, Lainhart SP, Shiavi R: Varia- 209-216). bility and biomechanics of synergy patterns of 78. Owen CA, Mubarak SJ, Hargens AR, et al.: In- some lower-limb muscles during ascending tramuscular pressures with limb compression. and descending stairs and level walking. Med Biol Eng Comput 7 6 : 6 8 1 - 6 8 8 , 1 9 7 8 . Clarification of the pathogenesis of the drug-in- 94. Townsend M A , Shiavi R, Lainhart S P , et al.: duced muscle-compartment syndrome. N Engl J Med 3 0 0 : 1 1 6 9 - 1 1 7 2 , 1 9 7 9 . Variability in synergy patterns of leg muscles 79. Perry J: T h e mechanics of walking. Phys Ther during climbing, descending and level walking 47:778-801, 1967. 80. Rasch PJ, Burke RK: Kinesiology and Applied of highly-trained athletes and normal males. Electromyogr Clin Neurophysiol 1 8 : 6 9 - 8 0 , 1 9 7 8 . Anatomy, Ed. 6. Lea & Febiger, Philadelphia, 95. Travell J: Ethyl chloride spray for painful mus- 1978 (pp. 317-318, 330, Table 17-2). cle spasm. Arch Phys Med Rehabil 3 3 : 2 9 1 - 2 9 8 , 81. Reynolds MD: Myofascial trigger point syn- 1952. dromes in the practice of rheumatology. Arch Phys Med Rehabil 6 2 : 1 1 1 - 1 1 4 , 1 9 8 1 . 96. Travell J, Rinzler SH: The myofascial genesis of pain. Postgrad Med 1 1 : 4 2 5 - 4 3 4 , 1 9 5 2 . 82. Rohen JW, Yokochi C: Color Atlas of Anatomy, 97. Travell JG, Simons DG: Myofascial Pain and Dys- Ed. 2. Igaku-Shoin, New York, 1988 (p. 423). function: The Trigger Point Manual. Williams & 83. Ibid. (p. 4 2 6 ) . Wilkins, Baltimore, 1983. 84. Sandstedt P, Nordell LE, Henriksson KG: 98. Weber EF: Ueber die Langenverhaltnisse der Quantitative analysis of muscle biopsies from Fleischfasern der Muskeln in Allgemeinen. volunteers and patients with neuromuscular Berichte Ciber die Verhandlungen der Kdniglich Sachsischen Gesellschaft der Wissenschaften zu disorders. A comparison between estimation Leipzig 3 : 6 3 - 8 6 , 1 8 5 1 . and measuring. Acta Neurol Scand 6 6 : 1 3 0 - 1 4 4 , 99. Whitesides TE: Tissue pressure measurements 1982. as a determinant for the need of fasciotomy. 85. Sandstedt PER: Representativeness of a muscle Clin Orthop 773:43, 1 9 7 5 . biopsy specimen for the whole muscle. Acta 1 0 0 . Wiley JP, Clement D B , Doyle DL, et al.: A pri- Neurol Scand 6 4 : 4 2 7 - 4 3 7 , 1 9 8 1 . mary care perspective of chronic compartment 86. Simons DG: Myofascial pain syndrome due to syndrome of the leg. Phys Sportsmed 7 5 : 1 1 1 - trigger points, Chapter 4 5 . In Rehabilitation Med- icine, edited by Joseph Goodgold. C. V. Mosby 120, 1987. Co., St. Louis, 1988 (see pp. 7 1 0 - 7 1 1 , Fig. 4 5 - 101. Yang JF, Winter DA: Surface EMG profiles dur- 9C). ing different walking cadences in humans. 87. Simons DG, Travell JG: Myofascial pain syn- Electroencephalogr Clin Neurophysiol 6 0 : 4 8 5 - dromes, Chapter 25. In Textbook of Pain, edited 491, 1985. by P.D. Wall and R. Melzack, Ed 2. Churchill Livingstone, London, 1989 (see p. 378, Fig. 102. Zeiss J, Ebraheim NA, Woldenberg LS: Mag- 25.9C). netic resonance imaging in the diagnosis of an- terior tibialis muscle herniation. Clin Orthop 244:249-253, 1989.

CHAPTER 20 Peroneal Muscles Peroneus Longus, Peroneus Brevis, Peroneus Tertius \"Weak Ankle\" Muscles HIGHLIGHTS: REFERRED PAIN and tender- peroneus brevis plantar flex and pronate (evert ness arising from myofascial trigger points and abduct) the foot. The peroneus tertius also (TrPs) in the peroneus longus and peroneus assists eversion, but dorsiflexes rather than brevis muscles concentrate primarily over the plantar flexes the foot. SYMPTOMS characteris- lateral malleolus, above, behind, and below it, tic of this myofascial pain syndrome are pain in and also extend a short distance along the lat- the ankle and ankle weakness. The referred eral aspect of the foot. An occasional spillover pain patterns of the peroneal muscles are differ- pattern may cover the lateral aspect of the mid- ent from, but might be confused with, those of dle third of the leg. Peroneus tertius TrPs refer the extensor muscles of the foot and toes. Lat- pain and tenderness primarily over the antero- eral compartment syndromes and entrapments lateral aspect of the ankle (anterior to the lateral of the common, supedicial, and deep peroneal malleolus) with spillover to the outer side of the nerves cause pain in a distribution similar to that heel. Proximal ANATOMICAL ATTACHMENTS caused by peroneal TrPs. The tendon of each for all three peroneal muscles are to the fibula peroneal muscle can rupture spontaneously. and adjacent intermuscular septa. However, the ACTIVATION AND PERPETUATION OF TRIG- longus and brevis form the lateral compartment GER POINTS can result from prolonged immo- while the tertius is part of the anterior compart- bilization of the leg and foot by a cast. These ment of the leg. Distally, the tendon of the per- TrPs are also perpetuated by the Morton foot oneus longus passes behind the lateral malleo- structure, crossing the legs when seated, wear- lus, runs obliquely across the sole of the foot ing high heels, wearing tight elastic around the from lateral to medial, and ends on the first calf, and by flat feet. PATIENT EXAMINATION metatarsal and medial cuneiform bones. The reveals some weakness of the involved mus- tendon of the peroneus brevis also curves be- cle(s), and the stretch range of motion is re- hind the lateral malleolus but ends on the tuber- stricted by pain. Examination of the feet for the osity of the fifth metatarsal. The tendon of the Morton foot structure shows (when this structure peroneus tertius passes in front of the lateral is present) a relatively short first metatarsal and malleolus and ends on the proximal portion of long second metatarsal bone. Calluses are likely the fifth metatarsal. INNERVATION of the per- to develop: under the heads of the second and, oneus longus and peroneus brevis muscles is sometimes, the third metatarsal bones; on the by the superficial peroneal nerve from spinal medial side of the distal phalanx of the great toe; nerves L4, L5, and S1. The peroneus tertius re- medially beside the head of the first metatarsal; ceives its innervation through the deep peroneal and sometimes along the lateral border of the nerve from spinal nerves L5 and S1. The basic sole anteriorly. Thorough inspection of the FUNCTION of the peroneus longus and per- shoes worn regularly includes examination of six oneus brevis muscles is to prevent medial incli- major features. TRIGGER POINT EXAMINA- nation of the leg over the fixed foot during the TION of the peroneus longus muscle reveals midstance phase of gait (controlling excessive taut bands palpable against the shaft of the fib- relative inversion and controlling mediolateral ula with TrP tenderness located about 2-4 cm balance in walking). The peroneus longus and below the head of the fibula. The local twitch re- 370

Chapter 20 / Peroneal Muscles 371 sponses (LTRs) that are readily elicited in the quires consideration of the nearby peroneal taut bands of these TrPs cause visible eversion nerves. The needle is aimed nearly straight to- of the foot. ENTRAPMENT of the common pero- ward the fibula to impale and inject the clearly neal nerve by a peroneus longus muscle that is identified TrP with 0.5% procaine solution. The tense because of active TrPs occurs as the approach to the peroneus brevis or peroneus nerve is compressed against the fibula by the tertius is through the posterolateral aspect of the taut muscle fibers or their tendon. Inactivation of leg. The needle passes deep to the tendon of the TrPs in this muscle relieves the related the peroneus longus. Passive lengthening of the symptoms of peroneal neurapraxia. INTERMIT- injected muscle, moist heat, and then full active TENT COLD WITH STRETCH requires applica- range of motion again complete the procedure. tion of ice or vapocoolant spray downward over The most important CORRECTIVE ACTION for the anterolateral aspect of the leg, ankle, and the patient with a peroneus longus or brevis foot. The regions of the lateral malleolus and lat- myofascial pain syndrome and the Morton foot eral heel must be included. During intermittent structure is one of two shoe corrections. Either cooling, to lengthen the peroneus longus and a first metatarsal felt pad is added to a modi- brevis, the foot is fully inverted and adducted fied sole insert that fits inside the shoe, or a and then dorsiflexed (ankle and first metatarsal). \"Flying Dutchman\" type of correction modifies To stretch the peroneus tertius, the foot is in- the outside of the shoe. A high heel or a spike verted and plantar flexed. A moist heating pad heel of any height can perpetuate peroneal rewarms the skin and then the patient executes TrPs and should be avoided. All patients with full active range of motion. Postisometric relaxa- peroneal TrP problems should perform the tion, ischemic compression, and stripping mas- Peroneal Self-stretch Exercise regularly at sage are also useful techniques to inactivate home to prevent recurrence of peroneus TrPs in these muscles. INJECTION AND longus and peroneus brevis TrP pain, tender- STRETCH of the peroneus longus muscle re- ness, and weakness. 1. REFERRED PAIN Peroneus tertius TrPs refer pain and (Fig. 20.1) tenderness along the anterolateral aspect of the ankle with a spillover pattern pro- Peroneus longus and peroneus brevis jecting downward behind the lateral mal- trigger points (TrPs) project pain and ten- leolus to the lateral aspect of the heel derness primarily to the region over the (Fig. 20.1B). lateral malleolus of the ankle, above, be- hind, and below it; they also extend a 2. ANATOMICAL ATTACHMENTS AND short distance along the lateral aspect of CONSIDERATIONS the foot (Fig. 20.1A).93,94,101 A spillover (Figs. 20.2 and 20.3) pattern of the peroneus longus TrPs may cover the lateral aspect of the middle The peroneus longus and peroneus brevis third of the leg.93,94 muscles, accompanied by the superficial peroneal nerve (see Fig. 20.9), fill the lat- Jacobsen47 reported a pain pattern referred from eral compartment of the leg. The per- peroneus longus and peroneus brevis TrPs as go- oneus tertius muscle lies in the anterior ing around the back of the lateral malleolus. Bates compartment with the tibialis anterior and Grunwaldt18 reported that, in children, the re- muscle and the deep peroneal nerve.77 ferred pain pattern of the peroneus longus muscle The cross section of the middle third of also concentrates behind the lateral malleolus, but the leg, Figure 19.3 in the previous chap- tends to extend up the side of the leg rather than ter, shows these relationships. along the side of the foot. Good43 attributed the symptoms in 15 of 100 patients with painful feet The peroneus longus muscle covers to myalgic spots in the peroneus brevis muscle. most of the peroneus brevis (Fig. 20.2A). Kellgren51 reported that the injection of 6% hyper- Proximally, the longus attaches to the tonic saline solution into the peroneus longus head of the fibula and to the upper two- muscle evoked pain referred to the ankle. thirds of the fibula's lateral surface. The common peroneal nerve enters the ante-

372 Part 3 / Leg, Ankle, and Foot Pain Peroneus Peroneus longus tertius Peroneus brevis Figure 2 0 . 1 . Pain patterns (dark red) referred from composite pain pattern for the peroneus longus and trigger points (Xs) at commonly observed locations in peroneus brevis muscles (medium red). The spillover the peroneal muscles. The essential patterns of re- pattern between the illustrated trigger points applies ferred pain and tenderness are solid red, and the red only to the peroneus longus trigger point. B, pain pat- stippling shows the less common spillover extension tern of the peroneus tertius muscle (light red). of pain. These trigger points all refer pain distally. A, rior leg through a gap between these two On the underside of the cuboid bone, upper attachments of the peroneus the tendon of the peroneus longus is longus muscle. In addition, the muscle thickened to form a sesamoid fibrocarti- anchors to adjacent intermuscular septa. lage.26 When this fibrocartilage ossifies, it Distally, it becomes tendinous in the becomes the os peroneum.62 This sesa- middle third of the leg. The tendon moid bone appears in approximately 20% curves behind the lateral malleolus and of mature individuals and its shape is ir- passes, together with the tendon of the regular. Phylogenetically, it may be in the peroneus brevis muscle, deep to the process of disappearing from the human superior peroneal retinaculum. On the race due to loss of its functional impor- lateral side of the calcaneus, these ten- tance for hallux opposability.62 dons occupy separate osseoaponeurotic canals. The tendon of the peroneus The peroneus brevis muscle is shorter longus then again curves sharply, this and smaller than the peroneus longus and time over the cuboid bone, and crosses lies deep to it. Distally, the belly of the the sole of the foot obliquely to attach to peroneus brevis extends beyond that of the ventral and lateral aspects of both the peroneus longus (Figs. 20.2A and the base of the first metatarsal and the 20.3). Proximally, the peroneus brevis at- medial cuneiform (Fig. 20.28). This long taches to the distal two-thirds of the lat- tendon of the peroneus longus attaches eral surface of the fibula deep to the per- opposite to the tendon of the tibialis an- oneus longus where there is overlap, and terior on the medial aspect of the base of to adjacent intermuscular septa (Fig. the first metatarsal bone.82 20.3). The tendon of this muscle travels with that of the peroneus longus within a

Chapter 20 / Peroneal Muscles 373 A Extensor digitoruum longus Peroneus longus Fibula Peroneus brevis Peroneus tertius Extensor digitorum Peroneus brevis tendon longus tendon Superior peroneal Inferior extensor retinaculum retinaculum Inferior peroneal Peroneus tertius retinaculum tendon Calcaneus Cuboid 5th metatarsal Peroneus longus tendon Calcaneus- B Medial 1 st metatarsal cuneiform Figure 20.2. Anatomical relations and attachments B, plantar view of the right foot. The bones to which of the right peroneus longus muscle (dark red). the peroneus longus muscle attaches are darkened. Deeper peroneal muscles are light red. A, lateral view. common synovial sheath as they curve close to and parallel to the extensor dig- behind the lateral malleolus under the su- itorum longus muscle, the tertius is usu- perior peroneal retinaculum (Figs. 2 0 . 2 ally anatomically distinct from the exten- and 2 0 . 3 ) . Farther distally, these tendons sor digitorum longus, contrary to conven- have separate synovial sheaths. The per- tional opinion.57 Proximally, it anchors to oneus brevis tendon anchors distally to the distal one-half to two-thirds of the an- the tuberosity on the lateral aspect of the terior margin of the fibula and to the adja- fifth metatarsal (Fig. 2 0 . 2 A ) . 2 6 cent anterior crural intermuscular sep- tum. The two lateral peroneal muscles at- The peroneus tertius muscle (Fig. 2 0 . 3 ) tach to the other side of this septum. The differs anatomically and functionally peroneus tertius is usually as large as or from the other two peroneal muscles. Al- larger than the extensor digitorum longus. though the peroneus tertius is located

374 Part 3 / Leg, Ankle, and Foot Pain Fibular head Intermuscular septum Peroneus longus cut and reflected Extensor digitorum longus Fibula Peroneus brevis Peroneus longus tendon, Peroneus tertius cut and reflected Inferior extensor retinaculum Superior peroneal Peroneus tertius retinaculum tendon Inferior peroneal 5th metatarsal retinaculum bone Peroneus brevis fleeted. The peroneus tertius is partly covered by the tendon peroneus brevis. The bones to which the peroneus brevis and tertius attach are darkened. Figure 20.3. Attachments of the deeper peroneal muscles (light red), right side, lateral view. The more superficial peroneus longus (dark red) is cut and re- Distally, the peroneus tertius normally oneus brevis and the flexor hallucis longus, and has a tripartite anchor: to the tubercle of distally to either the calcaneus or the cuboid.26 the fifth metatarsal, along the mediodor- sal surface of this metatarsal, and to the Supplemental References base of the fourth metatarsal. These tendi- nous projections spiral and tighten during T h e front view of the peroneus longus and per- passive inversion of the foot or straighten oneus brevis shows their relations to the superfi- and relax during passive eversion.57 cial peroneal nerve78 and also to the deep peroneal nerve.35,79 A front view also reveals the relation of Anatomists report many variants of the three the peroneus tertius muscle to the anterior tibial peroneal muscles. The peroneus tertius was ab- artery and deep peroneal nerve.\" Another front sent in 7.1-8.2% of specimens.57 A bifid peroneus view identifies the tendon of the peroneus tertius brevis was reported as the cause of symptoms that in relation to other tendons at the ankle.90 A rear required surgical correction.44 A commonly noted view that also includes the peroneal artery and tib- but rare (2%)57 muscle, the peroneus digiti ial nerve shows the thin slice of peroneus longus minimi, arises from the distal quarter of the fibula and peroneus brevis visible from behind.3,6 8' Lat- and attaches to the extensor aponeurosis of the eral views without vessels or nerves identify all fifth toe.15,26 A peroneus quartus muscle was pres- three peroneal muscles,37 portray the peroneus ent in about 13% of specimens. It attaches proxi- longus and peroneus brevis photographically,71 mally onto the back of the fibula between the per- and show in detail the relations of the three pero- neal tendons to other tendons at the ankle.74 A lat-

Chapter 20 / Peroneal Muscles 375 eral view also presents in detail the passage of the duce it; this is particularly evident when common peroneal nerve between the peroneus the foot is fixed during standing and longus muscle and the fibular head.70 Another lat- walking. At this time, these muscles often eral v i e w 7 8 and an anterolateral view4 show the rela- function through lengthening contrac- tions between all three peroneal muscles and the tions. superficial peroneal nerve. T h e dorsal view of the foot displays in detail the tendinous attachment of The peroneus longus and peroneus the peroneus tertius.40,57 brevis assist the tibialis posterior and soleus in controlling (decelerating) the Cross sections show the relation of the peroneus forward movement of the tibia over the longus to surrounding structures in 14 serial sec- fixed foot during the stance phase of tions,22 of the peroneus brevis in 11 serial sec- walking.97 tions,23 and of the peroneus tertius in five serial sections.24 The relations of all three peroneal mus- Matsusaka67 suggests that the peroneal cles appear in cross section at the lower part of the muscles (as well as the tibialis posterior middle one-third of the leg7 and above the middle and flexor digitorum longus) contribute to of the leg.77 Three cross sections, one through the control of mediolateral balance in walk- proximal third of the leg, one through the middle ing, together with the motion within the third of the leg, and one above the malleoli, delin- foot. eate the relations of the peroneus longus and per- oneus brevis muscles to neighboring structures.39 The peroneus longus, brevis, and ter- tius all act to evert the non-weight-bear- Photographs of well-muscled subjects disclose ing foot. A major difference in these mus- the surface contours produced by the peroneus cles is that the peroneus tertius dor- longus,34 by both the peroneus longus and per- siflexes the foot because its tendon oneus brevis muscles,6,64 and by the tendons at the crosses in front of the ankle joint, whereas ankle.72 the peroneus longus and peroneus brevis muscles plantar flex the foot since their A schematic drawing demonstrates clearly all tendons pass behind the ankle joint. bony attachments of the peroneus longus and per- oneus brevis muscles.5 Markings on the bones in- Actions dicate the attachment sites of the peroneus longus tendon to the plantar surface of the foot,12, 41 of the The peroneus longus and peroneus brevis cause brevis and tertius tendons to the dorsum of the foot,11,41 of the brevis tendon as seen from be- the foot, when free, to abduct (toe out)26,31 and to hind,10 of the longus and brevis tendons to bones in the leg,38 of all three peroneal muscles to bones evert (elevate its lateral side);26,31,97 together these in the leg,3,69,82 and of all three tendons to the foot.41 two movements produce pronation.26,31 Both mus- Various views show the synovial sheaths sur- cles assist plantar flexion of the foot.28,31, 97 Static rounding the tendons of the three peroneal mus- cles in the ankle region.9,42,73,83 loading of the foot without arch support up to 180 3. INNERVATION kg (400 lb) did not evoke activity in the peroneus Branches of the superficial peroneal longus muscle unless the foot was inverted. Then, nerve supply the peroneus longus and peroneus brevis muscles. This nerve con- the activity was minimal.17 tains fibers from the L4, L5, and S1 spinal nerves. The deep peroneal nerve supplies The peroneus tertius dorsiflexes the foot and as- the peroneus tertius in the anterior com- partment with fibers from only the L5 and sists eversion.26,32,97 Duchenne observed that when S1 spinal nerves. there was absence or weak development of the 4. FUNCTION peroneus tertius, the extensor digitorum longus The peroneal muscles, like most other lower limb muscles, frequently function substituted for the peroneus tertius in dorsiflex- to control movement rather than to pro- ion, abduction, and eversion.32 Because they attach to opposite sides of the same bone (first metatarsal), the tibialis anterior and peroneus longus muscles form an effective sling for control of inversion and eversion of the foot.80,82 The peroneus longus can produce about one- tenth of the moment for plantar flexion as the gas- trocnemius muscle (128 vs. 1123 kg/cm). The per- oneus brevis exerts only about half of the moment that the peroneus longus exerts for plantar flexion of the foot.97

376 Part 3 / Leg, Ankle, and Foot Pain adults. When the force plate measured a large lat- eral component of ground reaction force, EMG ac- Functions tivity of the peroneus longus was marked during midstance phase, while the amount of pronation Standing (eversion and abduction) of the foot was small. Matsusaka67 proposes that the peroneals control The peroneus longus plays a minor role during excessive inversion of the foot by preventing me- balanced standing at ease. Among 16 men and 16 dial inclination of the tibia over the fixed foot dur- women standing barefooted,16 only one man and ing the midstance phase of gait. Conversely, when two women showed some degree of continuous the lateral component of the ground reaction force electrical activity in this muscle. Another man was small, the peroneus longus remained inactive and five women showed intermittent activity. during midstance phase, and the tibialis posterior, When standing in high heels, all of the women ex- flexor digitorum longus, and extensor hallucis hibited some activity, and half of them generated longus were all active. continuous marked activity in the peroneus longus. Contrary to past speculation, the peroneus Krammer and associates57 concluded that the longus plays no important role in the static sup- peroneus tertius muscle evolved in bipedal pos- port of the long arches of the normal foot.17 How- ture for the purpose of shifting the line of body ever, this muscle may provide important support weight toward the medial margin of the foot. This for them during locomotion.16 shift from lateral to medial develops in infant standing balance and with the onset of walking, Tropp and Odenrick106 recently studied pos- and it occurs in each walking cycle of an adult tural control in single-limb stance using surface human. electromyography and force plate recordings of 30 physically active men. They found that the ankle Sports Activities played a central role in minor corrections of pos- tural balance. Peroneus longus electromyographic In a study of 15 highly trained track men,66 fine- (EMG) activity and the location of the center of wire intramuscular electrodes in the peroneus pressure on the force plate correlated closely with longus muscle showed EMG activity during the ankle position. When the body was in major dis- first half of stance phase of jogging. During run- equilibrium, however, subjects made corrections ning, this activity shifted toward midstance and at the hip. The mode of maintaining balance in lasted for a smaller percentage of the gait cycle. these subjects changed from an inverted pendu- When the subjects were sprinting, peroneus lum model to a multisegmental chain model when longus activity began shortly before stance phase adjustments at the ankle were no longer adequate and continued through most of that phase for a to- to maintain postural control. tal of about 2 5 % of the gait cycle. Patients with ankle instability, when tested by Examination of EMG activity from fine-wire standing on one foot following an ankle inversion electrodes in the peroneus longus muscle during a injury, showed no significant inversion or ever- standing vertical jump by five subjects50 revealed sion weakness compared with the other, unin- that activity during the take-off phase peaked at jured, ankle.63 The problem was apparently one of the time of toe-off. Only occasional minimal activ- impaired muscle control and balance rather than ity appeared during the flight phase, followed by one of muscle weakness. These subjects appar- return of vigorous activity during the landing ently were not examined for myofascial TrPs. phase, with activity gradually diminishing during the stabilization phase after landing. Walking Surface electrodes monitored bilateral EMG ac- Basmajian and Deluca16 established that, during tivity of the peroneus longus muscle during 13 level walking, the peroneus longus helps stabilize right-handed sports activities including overhand the leg and foot in midstance. The peroneus and underhand throws, tennis serve, golf swing, longus and the tibialis posterior, working in con- hitting a baseball, and one-foot jumps. Peaks of ac- cert, control the shift from inversion during early tivity characteristically appeared in the right leg stance to a neutral position at midstance. The per- preceding release of, or contact with, the ball and oneus brevis acts synchronously with the per- appeared in the left leg throughout and following oneus longus during ordinary walking. Through- release of a ball or on contact during a swing. In out most of the stance phase, the peroneus longus the one-foot jump, however, peaks of activity ap- generally is more active in flatfooted subjects peared in each leg prior to clearing the ground [with more flexible feet] than in \"normal\" sub- and on landing.20 jects.16 Matsusaka67 studied the control of mediolateral balance of the foot during walking in 11 normal

Chapter 20 / Peroneal Muscles 377 5. FUNCTIONAL (MYOTATIC) UNIT comes from myofascial TrPs, it responds well to myofascial management. All three peroneal muscles are prime movers for eversion of the \"free\" foot. Painful feet and calluses characteristic The primary agonist to the peroneal mus- of the Morton foot structure commonly cles for eversion is the extensor digitorum appear on the list of symptoms because longus.88 This muscle is likely to be over- this foot configuration aggravates per- loaded and to develop TrPs at the same oneus longus and peroneus brevis TrPs. time as the peroneal muscles because an involved weak peroneal muscle fails to Differential Diagnosis provide the help that the extensor dig- itorum longus needs at times of maxi- Myofascial Syndromes mum loading. Five extensor muscles of the lower limb The antagonists to the eversion func- project referred pain in patterns that tion of the peroneal muscles are primarily might be confused with those of the pero- the tibialis anterior and tibialis posterior neal muscles. They are the tibialis ante- assisted by the extensor hallucis longus rior and the long extensors and short ex- and flexor hallucis longus.88 The tibialis tensors of the hallux and of the lesser anterior and the peroneus longus attach toes. However, TrPs in these other mus- opposite to each other on the same cles do not refer pain behind the lateral bones.82 These antagonists are likely to be malleolus, to the heel, or to the lateral chronically overloaded when they must side of the leg. work against the increased tension of the peroneal muscles produced by shortened The tibialis anterior (see Fig. 19.1) pro- taut bands associated with their TrPs. jects medial, not lateral, anterior ankle pain and also refers pain to the great toe. Since the peroneus tertius, tibialis ante- As compared to the distribution of pain rior, and extensor digitorum longus are referred from peroneal TrPs, the extensor prime dorsiflexors, they are strong antag- digitorum longus (see Fig. 24.1A) refers onists to the plantar flexor function of the pain farther distally over the dorsum of peroneus longus and peroneus brevis the foot. The extensor hallucis longus muscles. pain pattern (see Fig. 24.1B) covers the medial, not the lateral, side of the dorsum 6. SYMPTOMS of the foot and extends farther distally, adjacent to the great toe. The composite Weakness of any of the three peroneal pain pattern of the extensor hallucis muscles can contribute to \"weak ankles.\" brevis and extensor digitorum brevis (see Patients with peroneal TrPs complain of Fig. 26.1) overlaps the peroneus tertius pain and tenderness in the ankle behind pattern on the dorsum of the foot, but and over the lateral malleolus, especially does not extend as far proximally as the after an inversion sprain of the ankle. ankle. These patients sprain their ankles fre- quently. Their ankles tend to be unstable The lateral heel pain referred from per- so that they cannot perform on a balance oneus tertius TrPs does not include the beam14 or ice skate. They are likely to entire Achilles tendon nor the bottom of have foot drop if the deep peroneal nerve the heel, as does the soleus referred pain is entrapped. pattern. Patients with peroneal TrPs, in addi- Because of the local tenderness associ- tion to inverting and spraining their an- ated with the pain referred to the ankle by kles because of inadequate peroneal mus- TrPs in the peroneal muscles, these myo- cle support, are also prone to ankle frac- fascial pain symptoms are easily mistaken tures. Treatment of the fracture by a cast for arthritis of the ankle joint.89 on the ankle, which immobilizes the per- oneal muscles, aggravates and perpetu- Entrapment Syndromes ates peroneal TrPs that cause ankle pain. In this situation, the fracture can be heal- Entrapment of the common peroneal ing, or fully healed, and not be the cause nerve, the superficial peroneal nerve, or of the ankle pain. When this ankle pain the deep peroneal nerve can produce symptoms of pain and paresthesias of the

378 Part 3 / Leg, Ankle, and Foot Pain anterolateral ankle and dorsum of the sion neurapraxia and a temporary peroneal nerve foot56 with weakness of the ankle92 that palsy. If this practice is continued too often and can be suggestive of peroneal myofascial too long, it can lead to lasting nerve damage.108 pain syndromes. Another reported postural cause of entrapment neuropathy of the common peroneal nerve was The common peroneal nerve leaves the harvesting a wheat crop in the squatting position popliteal space to swing around the neck by army personnel unaccustomed to this activ- of the fibula toward the front of the leg ity.85 where it enters the lateral compartment and passes deep to the peroneus longus The superficial peroneal nerve emerges muscle along the lateral edge of the soleus through the deep fascia in the lower third and lateral head of the gastrocnemius of the leg27 where it is vulnerable to acute muscle, as seen in cross sections.22 At this or chronic trauma and subject to entrap- level, it divides into the superficial and ment by the fascia.55 The pain and altered deep peroneal nerves (Fig. 20.9). Myofas- sensation without motor deficit in the cial TrPs in the peroneus longus muscle distribution of this nerve appears confus- can entrap the common peroneal nerve ingly like a combination of tibialis ante- close to the fibular head. Section 10 of rior and peroneus tertius myofascial pain this chapter presents this anatomy of the syndromes. However, this entrapment is nerve and its entrapment there in more not dependent on myofascial TrPs in detail. The superficial branch supplies these muscles. the structures in the lateral compartment and the deep branch supplies those in the Styf98 made the diagnosis of superficial pero- anterior compartment.25,56 neal nerve entrapment when examination re- vealed: (a) pain and altered sensibility over the Entrapment of the common peroneal dorsum of the foot; (b) a positive response to at nerve weakens both the anterior and lat- least one of three provocative tests; and (c) a su- eral compartment muscles. Loss of sensa- perficial peroneal nerve conduction velocity of tion is most marked in a triangular patch less than 44 m/sec or a fascial defect where the on the dorsum of the foot distally be- nerve emerges. The three provocative tests were tween the first and second toes, an area positive when the patient experienced the foot that is supplied exclusively by the deep pain in response to: (a) pressure applied where and superficial branches of the common the nerve emerges from the deep fascia while the peroneal nerve.27 patient actively dorsiflexed and everted the foot against resistance; (b) passive plantar flexion and Together, the symptoms of common inversion without local pressure over the nerve; peroneal nerve entrapment and the re- and (c) gentle percussion over the course of the ferred pain of peroneal TrPs strongly sug- nerve while maintaining passive stretch (Tinel's gest a ruptured intervertebral disc which, sign). if present, can also activate peroneal TrPs in a segmental distribution. Therefore, pa- Using the criteria listed, Styf96 identified three tients with such symptoms may have a mechanisms of entrapment among 21 patients myofascial pain syndrome with or with- with this diagnosis. Others also reported on pa- out neurological symptoms and signs; or tients with entrapment of the superficial peroneal their symptoms may be due to a combina- nerve..53,65,68,95 tion of radiculopathy, peroneal nerve en- trapment, and referred myofascial pain. Entrapment of the deep peroneal nerve by the extensor hallucis longus muscle is Reported causes of peroneal nerve palsy by considered in Section 10 of Chapter 24. compression in the leg include: a popliteal The Morton foot structure (the Dudley J. Morton foot configuration) must be distin- (Baker's) cyst,56,87 a ganglion (cyst) that locally re- guished from Morton's neuroma (Mor- ton's metatarsalgia). The latter is generally placed the peroneus longus muscle,19 a large thought to result from interdigital nerve entrapment in the region of the transverse fabella (sesamoid bone in the lateral head of the metatarsal ligament.1 The Morton foot gastrocnemius muscle) in seven cases,98 a cystic swelling in the peroneal nerve itself,87 and bunch- ing of the peroneus longus muscle after its rup- ture.56 The habit of crossing the legs may lead to the uppermost leg \"falling asleep\" due to compres-

Chapter 20 / Peroneal Muscles 379 structure is a variation in skeletal struc- in about 10% of individuals. When it has ture75 that usually is not of itself painful, suffered trauma and becomes painful, it but can cause problems for the muscles can be treated successfully either surgi- and other structures. Indeed, abnormal cally107 or conservatively.21 pressures caused by the structure could be a factor in development of the neuroma. The The os peroneum may fracture and rup- Morton foot structure is considered in Sec- ture the peroneus longus tendon99 when tions 7, 8, and 14 of this chapter. the individual tries to prevent a fall86 or imposes sudden inversion stress on the Lateral Compartment Syndrome ankle, often with an audible snap.21 Chapters 19 and 22 of this volume review Rupture of the peroneus brevis muscle the diagnoses of anterior and posterior occurred in a ballet dancer in the congen- compartment syndromes on pages 3 6 1 - ital absence of the peroneus longus mus- 362 and pages 443—444. The same princi- cle.29 ples apply here. The lateral compartment syndrome with pain along the lateral side Degenerative lesions of the peroneus of the leg that is aggravated by activity can brevis tendon were reported in 13 pa- be suggestive of peroneus longus and per- tients,91 and ruptures of the peroneus oneus brevis TrP pain, but the tenderness brevis tendon in nine patients.59,61 and tension of the musculature in the com- partment syndrome is diffuse, not local- 7. ACTIVATION AND PERPETUATION ized as in the myofascial syndromes.46 The OF TRIGGER POINTS lateral compartment syndrome is likely to develop in runners with excessive prona- Activation tion and abnormally mobile subtalar joints.17 It can also develop secondary to A fall with twisting and inversion of the rupture of the peroneus longus muscle.30 A ankle can overload the peroneus longus measured abnormal increase in compart- and peroneus brevis muscles and is likely ment pressure confirms the diagnosis.46 to activate TrPs in them. Ankle Sprain Weakness induced by prolonged immo- bilization, as by an ankle cast, predis- The trauma that causes a lateral ankle poses strongly to activation of these TrPs. sprain can also readily activate peroneal TrPs that refer pain and tenderness to the Active TrPs in the anterior gluteus min- ankle. Examination of the peroneal mus- imus muscle, which refer pain strongly to cles for TrPs discloses this source of the the lateral aspect of the leg, may induce symptoms. However, other causes of the satellite TrPs in the peroneus longus and pain should be ruled out. peroneus brevis muscles. Usually, injury to the lateral ligaments In a study of 100 patients, it was reported that a of the ankle results from an inversion- plantar flexion strain. The first structures motor vehicle accident rarely activated TrPs in to tear are the anterior lateral joint capsule and the anterior talofibular ligament.28 The the peroneus longus muscle.13 immediate region of the torn ligament is tender and swollen. Tenderness referred Perpetuation from TrPs usually includes a larger area without such marked swelling. Immobilization by a cast can perpetuate latent TrPs that were activated previously Muscle and Tendon Rupture by the initial trauma of a fracture or strain. Rupture of the peroneus longus muscle may produce a lateral compartment syn- The Morton foot structure (relatively drome.30 short first and long second metatarsals) with a mediolaterally rocking foot com- The os peroneum is a sesamoid bone of monly perpetuates TrPs primarily in the the peroneus longus tendon that develops peroneus longus93,94, 1 0 0 and also in the peroneus brevis muscles, but rarely in the peroneus tertius. Individuals may have an equally marked Morton foot structure bilaterally, but have pain only on one side, usually the side of a shorter lower limb. Similarly, bunions may ap-

380 Part 3 / Leg, Ankle, and Foot Pain pear the same on both feet, but may be petuate their TrPs. An indented red line painful on only one foot. Patients ask or marking around the leg indicates a why, if they have the same foot structure high probability of this constriction. The bilaterally, do they have pain only on one soleus muscle usually is too deep to be af- side? The answer is that the body is tilted fected. toward the shorter lower limb. When there is lower limb-length inequality, the 8. PATIENT EXAMINATION shorter limb usually carries more weight (Figs. 20.4-20.7) in standing, receives more forceful impact during ambulation, may be more fully in- Patients with latent TrPs in the peroneus verted at heel-strike, and has a delayed longus muscle are asymptomatic with re- toe-off. The limb may be short because of gard to pain but, for years, these latent low arch height caused by a hyperpro- TrPs may cause characteristic calluses nated, hypermobile foot on that side. and weak ankles.100 Chronic tension caused by active (or la- Examination of the feet frequently tent) TrPs in the antagonistic tibialis ante- reveals a relatively short first and long rior or tibialis posterior muscles tends to second metatarsal (Morton foot structure) overload the peroneus longus and per- with characteristic calluses. Shoes that oneus brevis muscles and to perpetuate show uneven wear and are poorly de- TrPs in them. signed for comfort, or are well designed but too tight, can make a major contribu- Sleeping with the foot strongly plantar tion to the pain problem. flexed places the peroneus longus and peroneus brevis muscles in the shortened While the patient walks, the clinician position for prolonged periods. This com- observes from behind to note excessive mon position aggravates their TrPs. pronation of the foot or other deviations. A mediolaterally rocking foot with asso- Crossing one leg over the other to com- ciated peroneus longus TrPs can pro- pensate for a small hemipelvis (see page duce a sense of ankle weakness severe 44, Chapter 4) can compress the common enough to convince some patients to use peroneal nerve in the uppermost leg a cane. against the underlying knee. The weight of the crossed leg may also traumatize the If, while sitting in a chair, the patient uppermost peroneus longus muscle, per- crosses the legs, he or she may be at- petuating TrPs in it. tempting to compensate for a small hemi- pelvis on the side of the uppermost Wearing high heels perpetuates pero- crossed leg. This seated pelvic asymmetry neal TrPs by shifting the body weight for- should be examined as described on ward onto the ball of the foot during pages 43-45 of Chapter 4 in this vol- standing, by reducing the base of support, ume. and by increasing the length of the lever arm against which the muscles must op- To examine for peroneus longus and erate. The resultant instability overloads peroneus brevis weakness, the patient the peroneus longus and peroneus brevis lies on the side not being tested. The muscles. A shoe with a spike heel of any clinician stabilizes the uppermost leg height provides an unstable base of sup- and places the foot in plantar flexion port that can overload the peroneal mus- and eversion (pronation); with the toes cles. relaxed, the patient then holds the foot in that position against resistance sup- Patients with flat feet and unsupported plied by the clinician, who presses arches are likely to have spot tenderness against the lateral border of the foot in and taut bands in the peroneus longus the direction of inversion and dorsiflex- and peroneus brevis muscles,58 probably ion.48,52 The calf muscles and long flex- because these muscles are then more ac- ors of the toes can also produce power- tive during the stance phase of walking.16 ful plantar flexion, but these two pero- neal muscles are the chief force for A tight elastic top of a long sock can eversion of the foot in plantar flexion. constrict circulation in the peroneus The peroneus tertius and extensor dig- longus, extensor digitorum longus, and itorum longus also produce eversion, gastrocnemius muscles by direct com- pression, like a tourniquet, and thus per-

Chapter 20 / Peroneal Muscles 381 Figure 20.5. Plantar palpation of the distal ends of the first two metatarsal heads, during strong extension of the toes, demonstrates the Morton foot structure (a relatively short first and long second metatarsal). Figure 20.4. Examination of the Morton foot struc- ture. Black marks locate the metatarsal heads in all positions. A, medial side view, good technique: flexion of the toes at the metatarsophalangeal joints and neu- tral position of the metatarsals proximally. B, standing weight-bearing position. Black marks clearly reveal the relatively short first and long second metatarsals. C, incorrect way of marking the metatarsal heads: the metatarsal bones are also flexed proximally at the tar- sometatarsal joints, restricting flexion of the toes at the metatarsophalangeal joints. but they dorsiflex, rather than plantar Figure 20.6. The long web between the second and flex the foot. Patients with peroneus third toes is characteristic of the Morton foot structure longus and peroneus brevis TrPs have (a relatively short first and long second metatarsal). difficulty holding that foot in eversion and plantar flexion against resistance as Morton Foot Structure compared with the uninvolved side. (Figs. 20.4-20.7) Baker14 describes this ratchety resis- tance to movement as \"breakaway\" In 1935, Dudley J. Morton, M.D.,75 described two weakness. The more active the TrPs, the structural variations in the foot, one or both of more marked is this weakness. which appeared regularly among 150 patients complaining of metatarsalgia. The most common Active peroneus longus and peroneus variation was hypermobility of the first metatarsal brevis TrPs cause pain on eversion effort (at the tarsometatarsal articulation) with laxity of with the foot already everted, and they longitudinal plantar ligaments; the other, nearly also painfully restrict passive inversion as common, was a relatively short first metatarsal range of motion. Peroneus tertius TrPs cause pain on active dorsiflexion in the dorsiflexed (shortened) position and limit passive plantar flexion.

382 Part 3 / Leg, Ankle, and Foot Pain Figure 20.7. Calluses frequently associated with the metatarsal, and lateral to the head of the fifth metatar- sal. Another callus occurs under the medial side of the Morton foot structure. The second toe usually extends head of the first metatarsal and still another usually farther from the foot than the first toe when the second appears on the medial side of the great toe along the metatarsal is longer than the first metatarsal. Thick interphalangeal joint. calluses may develop under the head of the second bone. Hypermobility of the first metatarsal over- with the fingers against the sole of the foot (Fig. loads the tibialis posterior and flexor digitorum 20.4A). The dorsal crease formed by the metatar- longus muscles.75 The short first metatarsal con- sophalangeal joint becomes visible. By marking the figuration tends to overload primarily the per- prominence of each metatarsal head with a pen, the oneus longus and, less frequently, the peroneus relative lengths of the five metatarsals become ap- brevis muscles. The peroneus brevis tendon does parent (Fig. 20.4S). The second toe usually stands not cross the sole of the foot to reach the first met- out as a prominent feature, as seen in Figure 20.46. atarsal bone as does the peroneus longus tendon. The locations of the metatarsal heads are more dif- ficult to mark accurately if the metatarsal bones are A relatively short first metatarsal occurs com- bent down with the toes (Fig. 20.4C). monly (approximately 40% of individuals).45 In both conditions described, the mechanical fault Figure 20.5 shows how to examine the plantar results in a failure of the first metatarsal bone to surface of the foot for a short first, long second carry its share of body weight (normally at least metatarsal relationship. The distal end of the sec- one-third) between heel-rise and toe-off during ond metatarsal extends farther than the end of the ambulation. Athletes with the Morton foot struc- first. Sometimes the phalanges of the second toe are ture who run about 80 km (50 miles) or more per so short that its tip does not extend beyond the end week are likely to develop painful symptoms.84 of the first toe, even though the second metatarsal is longer than the first. The length of the metatarsal is Chapter 4 of Volume l 1 0 5 reviews the literature the more important factor because it bears body relating to the relatively short first metatarsal weight. Therefore, the clinician should examine the bone. Section 14, Corrective Actions, of this chap- first two metatarsals for relative length, not just the ter describes the management of this condition. toes, when the patient has peroneal TrPs. This anatomical configuration causes medio- lateral rocking of the foot on the \"knife edge\" of a Usually, when the first metatarsal is shorter line extending from the heel through the head of than the second, the web of skin between the sec- the long second metatarsal bone. Travell100 em- ond and third toes is large compared with that be- phasized the muscular consequences of this tween the first and second toes (Fig. 20.6). This mechanical imbalance in foot dynamics. The mus- finding alerts the examiner to look at metatarsal cle imbalance and overload caused by the Morton length. foot structure can affect other muscles in addition to the peroneals. Common postural compensa- Although some individuals have a shorter first tions associated with the Morton foot structure in- metatarsal with normal distribution of body weight volve the vastus medialis, gluteus medius, and on the metatarsal heads, those with abnormal gluteus minimus (see Fig. 8.3). weight distribution develop calluses.45 These cal- luses usually develop in conjunction with TrPs in To examine for the Morton foot structure, the cli- the peroneus longus muscle. They occur under nician grasps the foot and flexes the joints of the the head of the second metatarsal (Fig. 20.7) and toes by supporting the heads of the metatarsals sometimes under the third and fourth metatarsal