Fig. 1.

The alpha angle is formed by the connecting lines (red lines) between the longitudinal mid-axis of the femoral neck and the axis which marked the lateral departure of the radius of the femoral head (blue circle). The alpha angle was 60.16° in this example (a). The weight-bearing line (WBL) is defined as the connecting line (red line) between the femoral head centre and the centre of the ankle. The MAD was measured as a distance in millimetres, as an alignment from the centre of the knee to the vertical line of the WBL (yellow line). The MAD was 22.37 mm (b)