Coexistence of anomalous m. peroneus tertius and longitudinal tear in the m. peroneus brevis tendon.

The longitudinal tear in the m. peroneus brevis tendon is frequently observed as a less common cause of chronic ankle pain and disability. In this case the rare association of a longitudinal tear in the m. peroneus brevis tendon and an anomalous m. peroneus tertius origin of muscle bulk and insertion were detected during a routine dissection of the lower left extremity. The m. peroneus tertius was originating separately from the fibula rather than as a slip from extensor digitorum longus. The muscle bulk was also bulkier than normal. The fanned-out m. peroneus tertius tendon adhered almost on the entire dorsal surface of the fifth metatarsal bone. According to our case report one of the possible causes of the longitudinal tear in the m. peroneus brevis tendon can be an anomalous m. peroneus tertius with its different origin and insertion points and muscle bulk, via changing the ankle motion mechanism. This anomaly should be considered in the patients presenting with ankle pain in the clinic.