The Role of the Flexor Hallucis Longus and Peroneus Longus in the Stabilization of the Ballet Foot

Abstract

The importance of the flexor hallucis longus (FHL) and peroneus longus tendons in the stabilization of the subtalar joint and the longitudinal arch of the foot was demonstrated in 8 fresh-frozen human cadaver foot and ankle specimens. Dissection of the foot was done to transect stabilizing structures including joint capsule and periarticular ligaments of the medial side of the subtalar, talonavicular, navicular-first cuneiform, and first metatarsocuneiform joints; the subtalar ligaments in the sinus tarsi and the lateral capsule of the middle subtalar facet were also transected. The FHL and peroneus longus tendons were isolated and the specimen fixed to a frame. Without any tension on the FHL and peroneus longus tendons, the foot was supple and unstable. With tension applied to the FHL tendon alone, the bony arch of the foot became rigid, with inversion of the subtalar joint, rising of the longitudinal arch, plantar flexion of the forefoot, and slight adduction of the forefoot. With tension applied to the peroneus longus tendon alone, the bony arch of the foot became rigid, with eversion of the subtalar joint, rising of the longitudinal arch, plantar flexion of the forefoot, and abduction of the forefoot. With tension applied to both the FHL and peroneus longus tendons synchronously, the bony arch of the foot rose and became rigid, with plantar flexion and neutral abduction-adduction position of the forefoot. When additional tension was applied to the peroneus longus, the rigid foot assumed a locked position in mild hindfoot eversion and forefoot abduction. These qualitative observations are consistent with the hypothesis that the FHL and peroneus longus are important stabilizers of the foot in dance (demi-pointe and pointe) and soccer (kick), and may provide an explanation for injury of these tendons with these activities.