A 15-year-old boy comes to the office with worsening right foot pain. The pain is described as a burning sensation that extends from the medial heel to the toes, accompanied by cramps in the pedal arch. He joined the track team at school about 3 months ago and has since developed this pain. In the last 2 weeks, he has had to stop track practice completely because of the pain. The patient is otherwise healthy and does not take medications. He is up to date on immunizations and eats a balanced diet. On examination, there is bilateral pes planus. The arches reform with tip-toe standing. The right ankle has full range of motion. The pain is reproduced by percussing the posterior medial malleolar area and by dorsiflexion-eversion and plantar flexion–inversion of the ankle. Squeezing the medial and lateral calcaneus and dorsiflexing the toes against resistance do not reproduce the pain. Which of the following is the most likely diagnosis of this patient?
Tarsal tunnel syndrome | |
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NSAID = nonsteroidal anti-inflammatory drugs. | |
This patient has tarsal tunnel syndrome (TTS) from posterior tibial nerve compression as it passes under the flexor retinaculum in the medial ankle. TTS is common in runners due to overuse (eg, tendinopathy, tenosynovitis) and repetitive microtrauma (poor biomechanics). Risk is increased with excessive tensile stress on the nerve (eg, pes planus, other lower extremity deformities), fractures (eg, calcaneus, medial malleolus), and posttraumatic scar tissue.
TTS presents with burning, neuropathic pain, numbness, and muscle cramps in the nerve distribution, primarily the posteromedial ankle, heel, sole, and toes. The pain, worsened by weight-bearing and relieved by rest, is reproduced by percussing the nerve in the posterior medial malleolar area (ie, Tinel sign) or by dorsiflexion-eversion and plantar flexion–inversion of the ankle, which stress and compress the nerve.
A provisional diagnosis can be made based on clinical features, although findings are often ambiguous. X-ray and MRI can help rule out underlying structural deformities, and nerve conduction studies sometimes confirm a physiologic defect at the tarsal tunnel (similar to carpal tunnel syndrome). Initial treatment includes nonsteroidal anti-inflammatory drugs, shoe orthotics, and activity modification. Corticosteroid injection can be useful (and diagnostic). Refractory cases may require surgical release.
(Choice A) Calcaneal apophysitis causes localized posterior calcaneal pain at the growth plate at the Achilles tendon insertion. Although it is associated with sports and typically develops with rapid growth spurt (as in this patient's age group), unlike TTS, the pain does not radiate to the toes and is typically dull.
(Choice B) Although running can cause calcaneal stress fracture, the pain typically is localized in the posterior calcaneus and elicited by squeezing the medial and lateral calcaneus (calcaneal squeeze test).
(Choice C) Plantar fasciitis (plantar fascia degeneration at its calcaneal insertion) causes plantar pain and is associated with pes planus. However, the pain is not neuropathic (ie, burning) and is typically elicited by traction on the fascia during dorsiflexion of the toes. A positive Tinel sign is not present.
(Choice E) The tibialis anterior muscle, located in the anterior leg compartment, is responsible for ankle dorsiflexion. Therefore, tendinopathy presents with anterior ankle (not heel or toe) pain, worsened by increased tendon stress during muscle contraction (eg, ankle dorsiflexion against resistance).
Educational objective:
Tarsal tunnel syndrome is caused by posterior tibial nerve compression beneath the flexor retinaculum in the medial ankle. It presents with burning pain or numbness in the posteromedial ankle, heel, sole, and toes, which is elicited by tapping on the nerve (ie, Tinel sign).