Complete replacement of the peroneus longus muscle by a ganglion with compression of the peroneal nerve: a case report.

In a 38-year-old woman, the entire muscle belly of the peroneus longus was replaced by a ganglion. Signs of peroneal nerve dysfunction resulted from direct pressure of the ganglion. Excision of the ganglion required a tenodesis of the peroneus longus tendon to provide a normal gait pattern which was maintained during a 17 month follow-up period. This entity needs careful, prompt evaluation to avoid neurological damage and to distinguish it from compartment syndrome.