Fig. 6. The subtrochanteric varus osteotomy results in both increased change of ΔX and ΔY coordinates compared with varus osteotomy at the neck shaft junction.

D: the distance between the base of neck and the level of subtrochanteric osteotomy, T: the level of subtrochanteric osteotomy, α: angle of varus correction, vr: varus angle of femoral neck before osteotomy.

x₀, y₀, z₀: x, y, z coordinates before osteotomy.

x_n, y_n, z_n: x, y, z coordinates after varus osteotomy at the neck shaft junction.

x_s, y_s, z_s: x, y, z coordinates after varus osteotomy at the subtrochanteric level.