Alterations in Muscle Coordination to Reduce Knee Joint Loading for People with Limb Loss.

purposePeople with unilateral transtibial amputation experienced a higher incidence of knee osteoarthritis due to abnormal movement patterns. This study aimed to explore alternations in muscle coordination to reduce mechanical burdens in their daily activities.

methodsFive males with unilateral transtibial amputation were recruited. Two daily activities (level walking and standing up from a chair) were simulated using muscle-driven simulation. Two cost functions were applied: minimising the knee adduction moment and minimising both the knee adduction moment and knee flexion moment. This enabled the identification of altered muscle coordination and any possible changes in kinematic patterns.

resultsFor people with unilateral transtibial amputation, reducing knee adduction angles during stance was found effective in reducing knee adduction moments. To mitigate peak contact forces at the intact knee, muscle activations of vasti and gastrocnemius should be decreased, while muscle activations of soleus should be increased during activities of level walking and standing up from a chair.

conclusionOur study suggested that minimising knee adduction moments was effective in reducing joint loading during level walking while minimising both knee adduction moments and knee flexion moments was effective during standing up from a chair. Therefore, the alteration of muscle coordination should be carefully designed for different daily activities.