INVERSE DYNAMIC CALCULATION OF 3D ANKLE JOINT KINETICS DURING GAIT: THE INFLUENCE OF CENTER OF PRESSURE DATA

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The purpose of this study was to jnvestigate the effect of the errors in the center of pressure (CoP) locations on three-dimensional (3D) ankle joint torque during the stance phase of gait. Kinematic and kinetic data from one healthy male subject (age: 22 yrs, height: 180 cm, body mass: 80 kg) were collected. Changes in ankle joint torque, calculated during inverse dynamics, during the stance phase of walking were obtained using simulated CoP data with up to ± 30 mm shifts in antero-posterior and medio-Iateral directions. Shift of the CoP in the antero-posterior direction caused a change of magnitude of the plantarflexor torque, while the torque pattern was not altered. On the other hand & change of the ankle inversion/eversion torques were greatly influenced by the CoP shifts in the medio-latera'l directions. A shift of ± 10 mm of CoP in the medio-Iateral direction caused a switch in the inversion/eversion torque of ankle joint. These results suggest the importance of accurate CoP determinations in inverse dynamics procedures.