Tarsal tunnel syndrome (TTS) is a condition characterised by symptoms of pain, altered sensation or neurological deficit affecting the branches of the posterior tibial nerve at the ankle. There may or may not be alterations in objective findings on neurological examination or in electrophysiological tests of nerve function. It is important to be aware in using the literature on TTS that some papers define the syndrome clinically and others on the basis of electrophysiology.
The cause of the syndrome is thought to be compression of the posterior tibial nerve branches in the “tarsal tunnel” formed by the flexor retinaculum and the medial malleolus. There are often one or more additional factors in nerve malfunction, such as diabetes or a space-occupying lesion. Compression may occur at the fibrous arch in abductor hallucis (distal tarsal tunnel syndrome) instead of, or in addition to, the flexor retinaculum.