Condylar Contact During Normal Walking and Lateral Trunk Sway Gait: an EMG-Driven Modeling Approach to Estimate Articular Loading

The knee adduction moment has a characteristic double hump pattern with the first peak generally larger than the second. Recently, Mundermann showed that walking with a lateral trunk sway can reduce the 1^st peak moment [1]. One might expect from this finding that there would be a decrease in medial compartment loading. This however may be too simplistic a view. Fregly et al. showed that a decrease in knee adduction moment does not guarantee a decrease in medial contact [2]. Moreover, the relationship between net joint moments and loading is not straightforward, especially when agonist/antagonist muscles are co-activated as occurs in patients with pathology. Computational methods can benefit by accounting for subject specific neuromuscular activation patterns while taking into account subject specific dynamics when predicting articular loading. In this paper we outline our EMG-driven modeling approach to predict articular loading during trunk sway for a patient with a force measuring instrumented knee implant. We hypothesized that walking with a lateral trunk sway would: (a) decrease medial contact force, and (b) increase contact force in the lateral compartment.