Anatomical variations in the insertion of the peroneus longus tendon

This study aimed to inspect anatomical variations in the insertion of the peroneus longus tendon (PLT) using a large sample of cadavers.

In total, 104 legs from 52 Japanese cadavers were used. The PLT was identified behind the lateral malleolus and carefully followed up to its insertion in the foot. All insertion slips of the PLT were located and documented.

Mainly, the PLT was inserted to the base of the first metatarsal (1MT) in all 104 ft. Attachment to the medial cuneiform was present in 20.2%, and the first dorsal interossei was present in 36.5%. The anterior frenular ligament was observed in 31.7%, and attachment to the flexor digiti minimi brevis and opponens digiti minimi was present in 31.7%. The posterior frenular ligament was observed in 5.8%. An additional band was observed in 3.9%, and the adductor hallucis consisting of a caput obliquum was present in 3.9%. No statistically significant differences in the PLT were observed between genders or laterality (right vs. left).

These findings suggest that the main function of the PLT is resisting the varus force on the 1MT; however, as the PLT has various attachment sites, it may also be involved in the stabilizing action of the longitudinal and transverse arches. Therefore, these variations and functions appear to be associated with a difficult diagnosis at the first clinical evaluation.