A COMPUTER SIMULATION OF THE EFFECT OF MUSCLE LOSS ON HIP JOINT EFFORT DURING THE STANCE PHASE OF TRANSFEMORAL AMPUTEE GAIT

The effect of muscle loss on the energy expenditure of hip joint, and its individual muscles, during stance phase of gait, was studied using a computer simulation. With each muscle as an ideal force generator, the lower extremity was simulated as a two-degree of freedom linkage with the hip and knee as its joints. Kinematic data and ground reaction forces were recorded by a gait analysis system. The forces exerted by muscles were determined to produce recorded hip and knee joint angles. Simulation results showed that, due to muscle loss, the work done by hip joint of the transected limb is more than that of the intact limb. Also, as more muscles are removed from the transected limb, residual muscles should do more work to flex or extend the hip. This finding is in line with the common practice in transfemoral amputation, according to which, it is important to maintain the length of residual limb as much as possible.