A biomechanical analysis of the talocalcaneal joint--in vitro.

The talocalcaneal (TC) joint has been a target for injuries and associated with other injuries of the lower extremity. The purposes of this investigation were to obtain a kinematic description of the TC joint, and determine the influence varied displacements and external loads had on this kinematic behavior. A fixture, allowing for a six degree of freedom configuration of the calcaneus and leg and allowing for load application in three orthogonal directions, was constructed. Equivalent screw displacement (ESD) parameters were used to describe TC joint motion. Results indicated external loading had little influence on the ESD parameters and orientation variables accounted for the majority of the influence. Large ESD parameter variation, within- and between-specimens indicated one average TC joint axis location and orientation was not appropriate for describing TC joint motion. It was concluded that foot categories based on TC joint structure and function be developed to provide a foundation upon which to base injury preventative measures, rehabilitative modalities and prosthetic designs.