Accessory muscles around the foot and ankle presenting as chronic undiagnosed pain. An illustrative case report and review of the literature

Abstract

The differential diagnosis of ankle pain is extensive. Pathology may be classified as intra- or extra-articular. Additionally, ankle pain may be traumatic or non-traumatic. One of the unusual differential diagnoses for pain in the ankle is an accessory muscle. Magnetic resonance imaging is the radiological investigation of choice. However, this is invariably reported as normal unless one specifically looks for an accessory muscle. The purpose of this report is to highlight important features of these muscles and to draw attention to this uncommonly reported condition.

Keywords: AHL; Accessory muscle; EDL; FDAL; FHL; Flexor digitorum accessorius longus; MRI; PCI; PQ; TCI; Tarsal tunnel syndrome; abductor hallucis longus; extensor digitorum longus; flexor digitorum accessorius longus; flexor hallucis longus; magnetic resonance imaging; peroneocalcaneus internus; pronator quadratus; tibiocalcaneus internus.