Tarsal tunnel

syndrome

in athletes

Case reports and literature review DAVID L.

From the

JACKSON,* MD, AND BIRGIT HAGLUND, MD

Department of Rehabilitation Medicine, College of Medicine, University of Kentucky, Lexington, Kentucky ankle with dorsiflexion, plantar flexion, inversion, and eversion, and no evidence of ligamentous instability. Neurologic examination revealed normal motor strength of the anterior and posterior leg muscles and foot intrinsics. Sensation was diminished to sharp/dull and two-point discrimination in the area supplied by the medial and lateral plantar nerves of the right foot. Reflex testing was normal in both lower extremities. Tinel’s sign was positive over the tarsal tunnel at the level of the medial malleolus on the right. In addition, there was a small, nontender nodule palpable just proximal to the tarsal tunnel. There was no tenderness to palpation at the calcaneous or metatarsal heads. Plain radiographs of the foot and ankle were normal. Electrodiagnostic testing revealed normal EMG readings of the muscles tested in both lower extremities, but abnormal nerve conduction of the medial and lateral plantar nerves on the right (Table 1). The right medial plantar nerve motor distal latency was 6.0 msec, with an amplitude of 4000 AV, whereas the left was 3.2 msec with 4200 ¡.LV. The sensory response was unobtainable on the right. The patient was started on a conservative treatment protocol that consisted of treatment with nonsteroidal antiinflammatory drugs (NSAIDs), steroid injection into the tarsal tunnel, and physical therapy using ultrasound and an ankle strengthening/coordination program. She responded well to treatment and had a good recovery and no further com-

Although foot pain and paresthesias have been noted in the literature for many years, the identification of a specific tarsal tunnel syndrome has been only relatively recent. This entity was not recorded in the literature until 1962, when Keck22 in the U.S. and Lam26 in Great Britain reported on it. Since that time, there have been several reports concerning the etiology, diagnosis and treatment of this syndrome in athletes. We present two cases of tarsal tunnel syndrome, one of a type that is being seen with increasing frequency, and one that is more unusual. We also review the present literature.

CASE REPORTS Case 1 A 39-year-old female was referred to our clinic for evaluation of right foot pain, numbness, and weakness of 2 months’ duration. The symptoms developed while she was enjoying a snow-skiing vacation using a new pair of alpine ski boots. Although she has been a skier for several years, this was the first episode of foot pain or numbness that she had experienced. She recalled that the pain developed during her 2nd day of skiing and persisted even though she discontinued skiing. She did not recall any pain specific to the fitting of her ski boots, but did admit that she used a pair of brand new, rear-entry, cable-adjusted boots. At the time of her presentation, the patient’s pain had greatly diminished, but she had persistent numbness along the plantar aspect of her right foot. On physical examination she was found to have equal leg lengths with no evidence of biomechanical malalignment (e.g., plano-valgus or varus deformity) of the foot/ankle. There was no evidence of swelling, erythema, or bony abnormality of the lower leg and foot. There was normal range of motion of the foot and

plaints. Case 2 A 42-year-old female runner presented to our clinic with a 6 week history of left foot pain and numbness that was worse at night and occasionally radiated up into her calf. Evaluation by two previous physicians had resulted in conflicting diagnoses: Achilles tendinitis and plantar fasciitis. Both physicians had recommended physical therapy and discontinuation of running. Being an avid 40 mile per week runner, this patient was very anxious to return to running, even though her symptoms were undiminished after 4 weeks of

*

Address correspondence and reprnt requests to’ David L Jackson, MD, Room 140, Chambers Medical Plaza, 820 South Limestone, Lexington, KY 40536-0226

nonrunning. 61

62

deformities, increased Q-angles (>24°), and symmetrical leg lengths. Running shoe analysis revealed a normal sole wear pattern but increased heel valgus in her semicurved, combination (board and slip) lasted shoes. She had tenderness over the medial plantar nerve posterior to the navicular tuberosity and a positive Tinel’s sign at the medial malleolus on the left. Decreased sensation to sharp/dull and light touch was found along the plantar aspect of the left foot,

tion velocities, seeing such studies as a potentially promising area for improving specificity in the diagnosis of the syndrome. The first objective evidence of an entrapment was documented by Keck in 196222 in his report of a case of bilateral tarsal tunnel syndrome. His case involved a boot camp army recruit who had compression of the posterior tibial nerve. The findings were verified at operative decompression, after which the patient experienced bilateral improvement in

but had

symptoms.

Biomechanical assessment revealed bilateral plano-valgus

a

normal motor examination.

Radiographs were normal with Electrodiagnostic studies revealed

bony abnormalities. a normal EMG reading of the muscles in the lower extremity, but slowing of sensory nerve conduction in the left medial and lateral plantar nerves (Table 1). The left medial plantar nerve (sensory) distal latency was 6.6 msec with an amplitude of 5 ~V and the right was 5.2 msec and 10 AV. The left lateral plantar nerve (sensory) distal latency was unobtainable. The right plantar nerve had a distal latency of 5.4 msec and an amplitude of 7 ~V. Motor conduction studies were normal. The patient was treated conservatively with NSAIDs, steroid injection into the tarsal tunnel, and custom-made orthotics. She responded well over a 6 week course of therapy no

that included using ice and ultrasound to the tarsal tunnel. She has since returned to running with no further com-

plaints. DISCUSSION Since the first appearance of tarsal tunnel syndrome in the literature, there have been relatively few reported cases and much speculation concerning its presumed status as an under-diagnosed entity. The postulation of peripheral nerve entrapment of the posterior tibial nerve is seen in the literature from 1946 through 1960, particularly as described by Kopell and Thompson23 in 1960. In 1962, Lam26 presented a unilateral case in which he attempted surgical decompression but was unable to provide objective evidence of entrapment of the posterior tibial nerve. In his description of the case, Lam suggested a possible vascular etiology as a conin the development of tarsal tunnel syndrome. He stressed the need for research into nerve conduc-

tributing factor

The tarsal tunnel is a fibroosseous tunnel, roughly comparable to the carpal tunnel .29 The floor of the tarsal tunnel is formed by the talus and calcaneus bones and the tibialis posterior, flexor digitorum longus, and the flexor hallucis longus. The roof is formed by the flexor retinaculum, also known as the lancinate ligament, a fan-shaped thin sheet of fibrous tissue extending from the medial malleolus to the calcaneus and to the proximal border of the abductor hallucis muscle. At the distal end, the tunnel is at its narrowest and blends into the superficial and the deep fascia of the abductor hallucis muscle.

The tibial nerve is one of the two major divisions of the sciatic nerve. It travels inferior to the medial malleolus, anterior to the Achilles tendon, and through the tarsal tunnel, which, as previously described, is an inelastic, fixed space covered by the flexor retinaculum. At the distal end of the tarsal tunnel, the tibial nerve branches. The actual location of these branches varies, although it is generally agreed that the branching takes place in the distal tarsal tunnel or soon after the nerve exits the tunnel. 6,16 The medial calcaneal branch of the posterior tibial nerve exits at the distal edge of the flexor retinaculum (or pierces it) to supply the skin of the heel and portions of the calcaneus. The medial plantar nerve is the largest branch of the posterior tibial nerve and runs superior to the abductor hallucis muscle belly, bound by the spring ligament supplying motor branches to the abductor hallucis, the flexor digitorum brevis, and the first lumbrical muscles. It also supplies sensory cutaneous branches to the plantar aponeurosis, the sole of the foot, and the first, second, third, and medial fourth toes. The lateral plantar nerve courses obliquely forward between the third and fourth muscle layers

TABLE 1

Electrodiagnostic test results

°

Distal

latency.

b Amplitude. ’No response.

63

deep to the abductor hallucis and flexor digitomuscles and superficial to the quadratus plantae muscle, emerging between the flexor digitorum brevis and abductor digiti minimi muscles. The lateral plantar branch of the posterior tibial nerve extends motor branches to the remaining muscles of the plantar aspect of the foot, superficial to the third plantar and fourth dorsal interosseous muscles and deep to the lateral two or three lumbrical and remaining interosseous muscles and both heads of the adductor hallucis muscle. It also provides cutaneous sensory nerve branches to the lateral half of the fourth and fifth toes. In general, entrapment of a nerve may occur anywhere the anatomical configuration allows compression of a nerve or continued inflammation after trauma. Because the tunnel is particularly inelastic, any condition that promotes inflammation or compression at the level of the tarsal tunnel may result in tarsal tunnel syndrome. Although entrapment may occur at any point from the proximal edge of the flexor retinaculum to the distal branchof the foot, rum

ings of the nerve, entrapment is most common at the anterior, inferior aspect of the tarsal tunnel where the nerves wind around the medial malleolus. 5,11 The lateral plantar nerve branch is more frequently affected than is the medial plantar nerve branch, as shown by Kaplan and Kernahan.2~ ETIOLOGY The most common etiology of tarsal tunnel syndrome is alteration of the normal spacial relationships secondary to fracture, dislocation, or direct pressure, such as from forced plantar flexion, acute or chronic eversion of the foot or

ankle, lipoma, ganglion, posttraumatic fibrosis, neuroma, or synovial hypertrophy in rheumatoid arthritis.’,’-’, 12,13,18, 26-211,33 Posttraumatic edema and chronic stasis of the posterior tibial veins or thrombophlebitis, or tortuous veins have also been implicated. 5,12,15,22,26 Systemic disease, such as gout with urate deposits, rapid weight gain, connective tissue changes associated with aging, fluid retention, and arthritic bony spurring have also been cited as causes of tarsal tunnel syndrome.5,8 Local vascular insufficiency has also been promoted as an etiology since pressure not only affects the nerve but also affects the vascular supply of the nerve. Even minimal edema can be responsible for vascular insufficiency in some

cases.3, 23, 25 In the athletic population, foot and heel pain is a common In long-distance runners, this pain is most likely due to plantar fasciitis. However, because of its location and vulnerability, damage to the posterior tibial nerve in the tarsal tunnel is becoming a more frequent finding in athletes. Many researchers feel that abnormal foot/ankle mechanics contribute significantly to the development of the syndrome.1O,2o,23,34 The repetitive nature of running, when associated with abnormal or excessive pronation, would place the posterior tibial nerve &dquo;on stretch&dquo; and at risk for injury. In fact, Rask35 described a condition he called &dquo;jogger’s foot,&dquo; in which excessive valgus or external rotation of the foot occurrence.

during running puts excessive stretch on the medial plantar nerve, resulting in tarsal tunnel syndrome. Henricson and Westlin15

presented

a

report of

runners

with chronic heel

pain caused by compression or entrapment of the calcaneal branch of the posterior tibial nerve, all of whom responded

surgical decompression. Tanz37 also described an entrapment syndrome of the calcaneal branch. He felt the well to

was due to a dynamic compression of the nerve by the abductor hallucis muscle when stretched, as would occur with excessive pronation. Obviously, any space-occupying lesion in the tarsal tunnel can produce the clinical syndrome by direct pressure or vascular insufficiency to the nerve. &dquo;Spontaneous&dquo; entrapment has been seen with local trauma, recent weight gain, fluid retention, and connective tissue changes seen with aging or disease states.5,8 The finding of increased valgus deformity of the foot as a predisposing cause, however, has also been reported in the literature.7,10,22,35 In athletes, this malalignment tends to increase the risk for development of tarsal tunnel syndrome. Direct trauma is also a factor, as was seen in our young snow-skier (Case 1).

pain

SYMPTOMS In the classic description of tarsal tunnel syndrome by Lam&dquo; and by Keck,22 symptoms include pain at the medial malleolus radiating to the sole of the foot, the heel, and sometimes the calf; paresthesias, dysesthesias, and hypesthesias; worsening of symptoms at night, with walking, or with dorsiflexion of the foot; weakness of toe flexion; increased fatigue of the foot; and trophic changes of the foot and nails. Since this description, other symptoms have been noted, including numbness and burning paresthesias on the plantar aspect of the foot and in the toes, which also may radiate up the leg. Sensory losses may occur in any of the three branches of the posterior tibial nerve in any combination. An early sign is loss of two-point discrimination. Later signs are motor loss or paralysis and proximal radiations. Pain is often poorly localized but may be reproduced by tapping over the nerve, producing Tinel’s sign. Tenderness distal or proximal to the area of entrapment may be present; this is referred to as Valleix sign.’ Forced dorsiflexion and valgus of the ankle causing pain and palpable fusiform swelling over the course of the nerve may also be present. Initially, symptoms may be intermittent but may become more constant over time.9,25,38 In addition to pain and sensory changes, weakness of the intrinsic musculature of the foot may be present but is, of course, difficult to evaluate and is a later finding than the sensory symptoms.5

DIFFERENTIAL DIAGNOSIS Tarsal tunnel syndrome is considered by many to be underdiagnosed.&dquo; Its recent appearance in the literature, along with improved electrodiagnostic techniques and documentation, have increased the frequency of diagnosis, although

64

Tibial

°

TABLE 2 studies

nerve

(motor)

Distal latency.

b Nerve conduction velocity.

Tibial

TABLE 3 studies (sensory)

nerve

specific symptoms and pressure of associated illness. Roentgenographs should be taken to check for evidence of degenerative changes, old fractures, bone spicules, and accessory ossicles, all of which

may contribute to

symptoms.

Electrodiagnostic studies should be done in all individuals suspected of having tarsal tunnel syndrome. Multiple studies have been performed by various researchers to establish objective electrodiagnostic measures of normal posterior tibial nerve function. In diagnosing tarsal tunnel syndrome, electrodiagnostic studies should include evaluation of the motor and sensory function of the medial and lateral plantar

Technique and electrode placement have varied slightly from study to study (Tables 2 and 3). In analyzing electrodiagnostic results in patients with documented tarsal tunnel syndrome at operative decompression, sensory nerve conduction velocities were more likely nerves.

°

Nerve conduction velocity.

h Amplitude. the actual incidence of the syndrome is not known. The diagnosis should be entertained in the differential of almost all infirmities of the foot and in some systemic illnesses where patients present with like symptoms. Heel and foot pain may be due to plantar fasciitis, as seen in runners; pressure on the medial anterior heel pad can be caused by soccer shoes. Other causes are rheumatologic disease, ankylosing spondylitis, Reiter’s disease, gout, or acute foot strain. Other possible causes of similar symptoms are interdigital neuroma, prolapsed metatarsal heads, plantar callosities, longitudinal arch sprain, localized rheumatoid disease, sciatica, peripheral neuritis, peripheral vascular disease, and

SI radiculopathy.25 Of particular interest in the running athlete is the differentiation of plantar fasciitis and tarsal tunnel syndrome, which have similar symptoms. Whereas plantar fasciitis tends to cause more heel pain at the origin of the plantar fascia (especially upon arising in the morning), tarsal tunnel syndrome tends to produce more medial heel and arch pain (at the abductor hallucis muscle). Pain caused by plantar fasciitis may improve with stretching and gradual running, whereas pain from tarsal tunnel syndrome worsens with running and may produce nocturnal paresthesias (especially up into the calf). In order to determine accurately the etiology of pain or paresthesia in the foot, it is important to consider the

to be abnormal than motor nerve conduction velocities at the level of mean ±2 SD. In one series,32 52.4% or 11 of 21 cases had abnormal motor nerve conduction velocities. However 90.5% or 19 of 21 patients exhibited abnormal sensory

conductions or absent potentials. Electromyographic studies of the lower extremities must also be performed when assessing whether tarsal tunnel syndrome is present. Several studies have shown that the motor conduction frequently may be normal in the plantar nerves, whereas EMG testing reveals denervation of the tibial-innervated muscles in the foot.5,ll,13,19,36 In addition, EMG findings in the muscles supplied by the tibial nerve above the tarsal tunnel would help differentiate between a radiculopathy, sciatic nerve entrapment and tarsal tunnel syndrome. As stated by Kraft24 in 1987, all patients being evaluated for tarsal tunnel syndrome should have a careful, needle examination study of the foot, leg, and back, in nerve

addition to nerve conduction studies. The presence of denervation potentials only in the distribution of the tibial nerve distal to the flexor retinaculum helps confirm the diagnosis of tarsal tunnel syndrome. Therefore, in order to properly diagnose tarsal tunnel syndrome, electrodiagnostic studies must include measurement of both the medial and lateral plantar nerves (motor

65

and sensory function), as well as EMG analysis of muscles in the foot and leg. In Keck’s initial description&dquo; of tarsal tunnel syndrome, he suggested that symptoms could be controlled by selflimitation of activities. Conservative management is generally considered to include treatment with a nonsteroidal antiinflammatory agent, local steroid injection, and wellfitting shoes and orthotic devices to improve biomechanics and decrease inflammation.3,15 Kopell and Thompson23 stated that if left untreated, most patients would become

months, with gradual resolution of inflammatory process, although some nerve atrophy might develop from continued pressure. If conservative management fails to provide symptomatic relief, release of the asymptomatic in

6 to 9

the

flexor retinaculum and resection of connective tissue bridges where possible is suggested, with dissection of both plantar branches beyond the compression but retaining all muscles whole.&dquo; Symptoms unrelieved by surgical release are attributed by Kaplan and Mann to be due to insufficient release distal to the impingement. Repeat release is indicated in this

instance. 21,30

running athlete, abnormal foot mechanics appear major etiologic factor in the development of tarsal tunnel syndrome. Therefore, unless the clinician addresses this aspect of treatment, correcting the excessive pronation, the condition will be difficult to control. Proper management of the runner with tarsal tunnel syndrome includes ice, NSAIDs, steroid injection, flexibility exercises, and custommade foot orthotics to help control abnormal mechanics. In the

to be the

SUMMARY Tarsal tunnel syndrome is being seen in increasing frequency in the athletic population, especially in the running athlete. The sports medicine physician must be cognizant of this entity, including proper diagnostic testing and management.

REFERENCES 1

2

3 4

5

Belen J Orthodromic sensory nerve conduction of the medial and lateral plantar nerves A standardization Am J Phys Med 64. 17-23, 1985 Buchthal F, Rosenfalk A: Evoked action potentials and conduction velocity in human sensory nerves Brain Res 3 1-122, 1966 Cangialosi CP, Schnall SJ The biomechanical aspects of anterior tarsal tunnel syndrome J Am Pod Assoc 70 291-292, 1980 DeLisa JA Tarsal tunnel syndrome American Association of Electromyography and Electrodiagnostics, Course D, pp 17-22, 1984 DeLisa JA, Saeed MA The tarsal tunnel syndrome Muscle Nerve 6. 664-

670, 1983

6 Dellon AL, Mackinnon SE Tibial nerve branching in the tarsal tunnel Arch Neurol 41 645-646, 1984 7 DiStefano V, Sack JT, Whitaker R, et al Tarsal tunnel syndrome Review of the literature and two case reports. Clin Orthop 88 76-79, 1972 8 Edwards WG, Lincoln CR, Bassett FH, et al The tarsal tunnel syndrome diagnosis and treatment JAMA 207 77, 1969 9 Ennght T, Liang GC, Fox TA, et al. Tarsal tunnel syndrome with ankylosing spondylitis Arthntis Rheum 22 77-79, 1979 10 Francis H, March L, Terenty T, et al: Benign joint hypermobility with neuropathy Documentation and mechanism of tarsal tunnel syndrome J Rheumatol 14 577-581, 1987 11 Fu K, DeLisa JA, Kraft G Motor nerve latencies through the tarsal tunnel in normal adult subjects: standard determinations corrected for temperature and distance Arch Phys Med Rehab 61 243-248, 1980 12. Goodgold J, Kopell HP, Spielholz NI: The tarsal tunnel syndrome, objective diagnostic criteria N Engl J Med 273. 742-745, 1965 13 Grabois M, Puentes J, Lidsky M Tarsal tunnel syndrome in rheumatoid arthritis Arch Phys Med Rehab 62 401-403, 1981 14 Guiloff RJ, Sherratt RM Sensory conduction in medical plantar nerve J Neurol Neurosurg Psych 40 1168-1181, 1977 15 Henricson AS, Westlin NE Chronic calcaneal pain in athletes. Entrapment of the calcaneal nerve? Am J Sports Med 12 152-154, 1984 16 Horwitz MT: Normal anatomy and vanations of the penpheral nerves of the leg and foot Arch Surg 36 626-636, 1938 17 Irani KD, Grabois M, Harvey SC. Standardization technique for the diagnosis of tarsal tunnel syndrome Am J Phys Med 61 26-31, 1982 18 Janecki CJ, Dovberg JL Tarsal tunnel syndrome caused by neurilemona of the medial plantar nerve J Bone Joint Surg 59A 127-130, 1977 19 Johnson EW, Ortiz PR Electrodiagnosis of tarsal tunnel syndrome Arch Phys Med 47 776-780, 1966 20 Joubert MJ Tarsal tunnel syndrome S Afr Med J 46 507-508, 1972 21 Kaplan PE, Kernahan WT Tarsal tunnel syndrome—an electrodiagnostic and surgical correlation J Bone Joint Surg 63A. 96-99, 1981 22 Keck C The tarsal-tunnel syndrome J Bone Joint Surg 44A 180-182, 1962 23 Kopell HP, Thompson WL Peripheral entrapment neuropathies of the lower extremity N Engl J Med 262 56-60, 1960 24 Kraft GH Tarsal Tunnel Syndrome American Association of Electromyography and Electrodiagnostics, Course D, pp 29-34, 1987 10th Annual AAEE Course, 1987 25 Lam SJS Tarsal tunnel syndrome J Bone Joint Surg 49B 87-92, 1967 26 Lam SJS A tarsal tunnel syndrome Lancet 2 1354-1355, 1962 27 Linscheid RL, Burton RC, Fredencks EJ. Tarsal-tunnel syndrome South Med J 63 1313-1323, 1970 28 Lloyd K, Agarwal A Tarsal tunnel syndrome, a presenting feature of rheumatoid arthritis Br Med J 3 32, 1970 29 Mackinnon SE, Dellon AL Homologies between the tarsal and carpal tunnels Implications for surgical treatment of the tarsal tunnel syndrome

Contemp Orthop 4(4) 75-78, 1987 30 Mann, RA Tarsal tunnel syndrome Orthop Clin North Am 5 109-115, 1974 31 Oh SJ, Sarala PK, Kuba T, et al: Sensory nerve conduction velocity of the plantar nerves. A supenor objective diagnostic test for tarsal tunnel syndrome Trans Am Neurol Assoc 103 356, 1979 32 Oh SJ, Sarla PK, Kuba T, et al Tarsal tunnel syndrome: electrophysiological 327-330, 1979 study Ann Neurol 5 33 Pho RWH, Rasjid C A ganglion causing the tarsal tunnel syndrome Report of a case Aust N Z J Surg 48 96-98, 1978 34 Radin EL Tarsal tunnel syndrome Clin Orthop 181 167-170, 1983 35 Rask MR Medial plantar neuropraxia (jogger’s foot) Report of 3 cases Clin Orthop 134 193-195, 1978 36 Saeed MA, Gatens PF Compound nerve action potentials of the medial and lateral plantar nerves through the tarsal tunnel Arch Phys Med Rehab 63 304-307,1982 37 Tanz SS Heel pain Clin Orthop 28 169-178, 1963 38 Wilemon WK Tarsal tunnel syndrome A 50-year survey of the world literature and a report of two new cases Orthop Review 8(11) 111-117, 1979