Fig. 2

a Articulation contacts points on the medial and lateral femoral condyles and tibial surfaces of the TKA component at a flexion position. b Articular contact paths on the medial and lateral femoral condyles and tibial surfaces of the TKA component during flexion of the knee. Contact lines were illustrated at different flexion positions. The axial tibial rotation due to articulations on femoral condyles or tibial surfaces at each flexion interval was calculated as the angle between the two adjacent contact lines on the femoral condyles or tibial surfaces of the TKA component