Fig. 4

Radiographic measurement using a lateral knee radiograph. A AFO was defined as the distance between the anterior femoral cortex and the anterior aspect of the femoral condyle or femoral component (red double-headed arrow). B ISR was defined as the ratio of the distance between the distal pole of the patella and the tibial tuberosity (a) to the distance between the distal and proximal poles of the patella (b). AFO anterior femoral offset, ISR Insall–Salvati ratio