Fig. 2

Illustrations of two dynamic biomechanical markers associated with OA progression. A Dynamic varus alignment (in red) is defined as a lateral offset of the knee during gait. A healthy knee is expected to maintain a more neutral position during motion (blue line). B Reduced knee flexion excursion during loading (in red) is characterized by limited flexion of the knee during loading. This occurs during the phase in which the knee acts as a shock-absorber. A healthy knee is expected to have substantial flexion (dashed blue line) to adequately absorb the loads induced by the body weight