Fig. 1

a The two-dimensional/three-dimensional registration technique uses computer-assisted design models to reproduce the spatial position of femoral and tibial components from single-view fluoroscopic images. b The axial rotation angles of the femoral component relative to the tibial component were denoted as positive from minimum flexion to maximum flexion. Medial and lateral rollbacks were defined as the AP translation of the medial and lateral sides from minimum flexion to maximum flexion. c A medial pivot was defined if the lateral side moved more than the medial side, the lateral pivot was defined if the medial side moved more than the lateral side, and the central pivot was defined if the medial and lateral sides moved in opposite directions