Does Peroneal tertius in absentia affect the range of motion of foot dorsiflexion and eversion? A kinesio-anatomical study.

Abstract

Ankle dorsiflexion and eversion are key swing phase gait movements attributed to peroneus tertius (PT) muscle. PT muscle has been reported to be absent in the different populations. Whether absence of PT muscle leads to changes in Range of Motion (ROM) of ankle dorsiflexion and eversion or not is uncertain.

The study was conducted on 338 legs taking from 169 subjects with age ranging from 15 to 70 years. The presence of PT was determined using surface visualization of the tendon marking and the range of motion of ankle dorsiflexion and eversion was measured.

The peroneus tertius was absent in 39 (21 right and 18 left) out of 338 legs studied. There was no significant difference between the mean ROM of foot dorsiflexion and eversion in subjects without PT relative to subjects with PT. The ROM of foot eversion was significantly higher in females. The ROM of leg dorsiflexion showed a significant negative correlation with age.

In the absence of PT, there is recruitment of neighboring muscles (Extensor digitorun longus, Peroneus longus and brevis) which interact with biomechanical changes in the structures around the ankle joint to prevent functional compromise of ankle dorsiflexion and eversion.

Keywords: Peroneus tertius, range of motion, dorsiflexion, eversion, absentia.