Watson-Jones tenodesis for ankle instability. A mechanical analysis in amputation specimens.

The stabilizing effect of a modified Watson-Jones ankle tenodesis was studied in 10 lower extremity amputation specimens using a kinesiologic testing device. Cutting of the lateral ligaments caused maximal instability in adduction of the entire hindfoot joint complex, as well as of the talocalcaneal joint. The tenodesis restricted adduction and internal rotation when compared with the movement pattern with intact ligaments. Instability in external rotation persisted because the tenodesis did not restore the function of the calcaneofibular ligament. Our study confirms clinical observations that the Watson-Jones ankle tenodesis prevents abnormal inversion of the hindfoot, but does not restore hindfoot kinematics.