Asymmetric Changes in Intersegmental Covariation Across Ambulation Levels and Prosthetic Devices for Transfemoral Amputee Gait

Resolution of kinematic redundancies during human locomotion has previously been described by the law of intersegmental coordination. This law describes how elevation angles of the thigh, shank, and foot covary during gait. Previous work showed that the covariation plane (CVP) orientation can provide insight into gait pathologies such as Parkinson's Disease (PD) and Cerebellar Ataxia (CA). We assess the intersegmental CVP for locomotion with an above knee amputation, as compared to other movement pathologies, showing that amputees do follow the law of intersegmental coordination. Specifically here we considered locomotion across different ambulation capacities (K level) and knee and ankle prostheses. Our results showed that there is an asymmetry in how the CVP varies with walking speed for the amputated leg versus the contralateral leg. Also, we showed that with certain ankle and knee prostheses the CVP of the contralateral leg varies with speed similarly to able-bodied subjects; this is not the case for the amputated leg. Importantly, this result may have implications for reduction of the energetic cost of walking with a prosthesis. Additionally, using the shape score, we present an important result showing that amputee gait seems to be more poorly coordinated than that of PD or CA subjects. Future work will be expanded to better understand how coordination differs in amputee subjects and whether powered prostheses improve this coordination.