Fig. 2

The measurement method of lower limb alignment and typical cases

The femoral mechanical axis is determined by drawing a line connecting the centre of the femoral head and the midpoint of the femoral condyle. The tibial mechanical axis is determined by drawing a line connecting the midpoint of the tibial shaft (spinous process) and the midpoint of the talus. The HKA angle is the angle formed by the intersection of these two lines. In typical cases, the HKA angle changed from 16.61° preoperatively (a) to 10.15° postoperatively (b) and from 4.95° (c) to -4.50° (d)