Fig. 3

TAD measurement after FNS A Hip anteroposterior position B Hip lateral position The long dotted line (red) indicates the femoral head and neck mid-axis, the distance from the tip of the bolt (Tip) to the apex of the femoral head and neck mid-axis and femoral head-articular surface junction (Apex) was measured on the anteroposterior and lateral side respectively, the distance between the anteroposterior and lateral side (Xap), the distance between the anterior and posterior side (Xlat), and the widths of anteroposterior and lateral side bolt measurements (Dap, Dlat), and the amplification factor was corrected with the actual bolt width (Dtrue) (TAD = Xap×(Dtrue/Dap) + Xlat×(Dtrue/Dlat))