Hindfoot motion after isolated and combined arthrodeses: measurements in anatomic specimens.

Passive motions at the subtalar joint, talonavicular joint and calcaneocuboid joint were measured in eight ankle specimens, using an ultrasonic motion analysis system. Arthrodeses of the three joints were performed in all feasible combinations and the resulting motion change at the unfused joints was determined. Motion at the subtalar joint was not significantly affected by fusion of the calcaneocuboid joint, reduced to one quarter by fusion of the talonavicular and calcaneocuboid joints (double arthrodesis) and almost completely eliminated with all other fusions. Motion at the talonavicular joint was not significantly affected by calcaneocuboid fusion and reduced to approximately one third with the subtalar and the double arthrodesis. Motion at the calcaneocuboid joint was not significantly reduced by subtalar fusion but almost completely eliminated in all fusions involving the talonavicular joint. It is concluded that the talonavicular joint is the key articulation for hindfoot motion. Double arthrodesis preserved significant motion at the subtalar joint. Fusion of the calcaneocuboid joint had no significant influence on remaining hindfoot motion.