Baxter's Nerve Entrapment

Introduction

Up to 20% of cases of chronic heel pain are caused by Baxter's nerve entrapment. However, it's an often-overlooked source of heel pain.

Anatomy

The first branch of the lateral plantar nerve has sensory components to the calcaneal periosteum, the long plantar ligament and the lateral plantar skin, and motor fibers to the abductor digiti minimi, flexor digitorum brevis and quadratus plantae. The first branch of the lateral plantar nerve originates from the lateral plantar nerve near the bifurcation of the tibial nerve or it may arise from the tibial nerve prior to its bifurication. It then dives through the superficial fascia at the superior border of the abductor. At this level, the investing fascia of the abductor is thicker laterally because of the reinforcement from the interfasicular ligament in continuity with the medial intermuscular septum.2 It travels distally between the lateral abductor fascia and the medial edge of the quadratus. When it reaches the lower border of the abductor hallucis, it turns and courses laterally, passing 5.5 mm anterior to the medial calcaneal tuberosity (or spur) and between the quadratus and the underlying flexor brevis until it reaches its distal target of the abductor digiti minimi.

Differential diagnosis

• Plantar fasciitis
• Seronegative arthritis-induced inflammation
• Tarsal tunnel syndrome
• Medial calcaneal neuritis
• Heel spurs,
• Calcaneal stress fractures
• Periosteal inflammation