Triple Arthrodesis

Abstract

Under closed kinematic chain conditions, the functions of the ankle and the tarsal joints are coupled. Exorotation of the lower leg induces exorotation of the talus and supination of the tarsus, and vice versa. Endorotation of the lower leg and pronation of the tarsal joints are also coupled this way. The varus or valgus position of the calcaneus and the form of the hindfoot are determined by rotations and translations of the other tarsal bones around the talus. The most important joint in the tarsus, determining the mobility of this complex, is the talonavicular joint. In the present description of a surgical technique for performing a triple arthrodesis of the tarsus, it is emphasized that the position of the hindfoot can be corrected and is determined by maneuvering the foot around the talus at this joint. After release of the tarsal joints and preparation for fusion, in most cases, a neutral position of the tarsus can be acquired without resection of bony wedges. The surfaces thus maintain optimal congruency and contact, which is beneficial for acquiring bony fusion. The form of the foot is corrected without shortening. Screw fixation is used, and a near 100% fusion rate is feasible without the use of autograft or allograft bone. In case of deformity, triple arthrodesis is seldom a stand-alone procedure. Additional soft tissue procedures, for instance lengthening of the tendon Achilles, and realigning of the forefoot in relation of the tarsus are then mandatory in acquiring a plantigrade foot and optimal stability.