Action of the peroneus longus tendon on the first metatarsal against metatarsus primus varus force.

A medially directed force was applied to the first metatarsal in 10 cadaver feet. The peroneus longus tendon was subjected to a pull of 5 pounds. The soft tissues between the first and second metatarsals were cut sequentially, starting with the skin on the dorsal and plantar aspect, followed by the intermetatarsal ligament and adductor hallucis tendon, and, finally, the peroneus longus tendon at its distal insertion. Dorsoplantar radiographs while weightbearing were taken after each sectioning. A statistically significant varus displacement of the first metatarsal was observed only after transection of the peroneus longus tendon. It was concluded that the peroneus longus tendon is a strong retaining mechanism of the first metatarsal.