Entrapment of the first branch of the lateral plantar nerve is a commonly missed cause of recalcitrant plantar heel pain. The diagnosis is made on a clinical ground with maximal tenderness at the site of nerve entrapment. Treatment of the nerve entrapment is similar to that for plantar fasciitis, with rest, activity modification, nonsteroidal antiinflammatory drugs, stretching exercise, and local steroid injection. Surgical release of the deep abductor hallucis fascia is indicated when conservative treatment failed. Endoscopic release of the nerve through the dorsal and plantar portals, as well as endoscopic plantar aponeurosis release, is a feasible approach. P lantar heel pain is one of the most common problems faced by orthopaedic surgeons. Differential diagnoses include plantar fasciitis, entrapment of the first branch of the lateral plantar nerve, fat pad disorders, stress fracture of the calcaneal body, fatigue fracture of the medial calcaneal tuberosity, rupture of the plantar aponeurosis, tarsal tunnel syndrome, sciatica, painful piezogenic heel papules, glomus tumor of the heel pad, and bone and soft tissue tumor.
1The most common cause of plantar heel pain is plantar fasciitis, which is usually cured with conservative care. Entrapment of the first branch of the lateral plantar nerve, which can occur together with plantar fasciitis, is one of the most commonly overlooked causes of plantar heel pain. The nerve consists of sensory fibers for the calcaneal periosteum and the long plantar ligament as well as motor fibers for the quadratus plantae, flexor digitorum brevis, and abductor digiti quinti muscles.2 Nerve entrapment syndrome has previously been considered only in cases with intractable heel pain, but it may play a role in the early phases of painful heel syndrome.
3Diagnosis of the nerve entrapment is made on clinical grounds. Early morning pain is uncommon with isolated nerve entrapment. It tends to cause more pain at the end of the day or after prolonged activity. This may be related to the engorgement of a vessel accompanying the first branch of the lateral plantar nerve causing ischemia of the nerve rather than pure static compression of the nerve by the fascia. 4 The pathognomonic sign is maximal tenderness at the medial border of the plantar heel where the nerve entrapment occurs.1 The diagnosis can be confirmed by injection of lidocaine and bupivacaine into the region of the nerve, resulting in complete, albeit temporary, relief of the pain.