3-DIMENSIONAL ANALYSIS OF THE TALOCRURAL AND SUBTALAR JOINTS IN SINGLE-LIMB STANCE

A quasi-static three-dimensional model of the rear foot was developed to enable calculation of joint motion and net torque with respect to t alocrural and subtalar joint axes. The functional behaviour of these j oints was analysed during single-limb stance. Six female soccer player s with unilateral functional instability of the ankle joint were exami ned. Recordings were performed both with eyes open and eyes closed. Th e rear-foot model was implemented into an optoelectronic motion analys is system together with a force plate. The subtalar torque precedes th e angular movement by 0.1-0.2 s, indicating active postural correction s. Up to a certain limit of subtalar joint inversion, the external eve rting torque increases. If the inversion is further increased an exter nal inverting torque is obtained. With eyes closed the amplitudes incr eased for joint motions, torques, centre of pressure trajectories, she ar forces, and vertical forces. All events found with external inverti ng torques occurred when standing on the injured foot with the eyes cl osed.