Evaluation of different performance criteria for accurate estimation of muscle coordination and knee joint contact forces

Optimization techniques solve the muscle redundancy problem assuming some performance criterion, such as muscle activation, force, stress, metabolic energy or joint contact forces determines muscle coordination. However, it is not yet clear which criterion describes muscle coordination and contact forces the best. Hence, this study aimed at thoroughly evaluating previous hypotheses on performance criteria by validating both predicted muscle coordination and contact forces for multiple subjects. Muscle activity and stress-based criteria with a power of 3 to 4 resulted in the best agreement between predicted and measured values.