Fig. 1

Radiographic measurement. The calcar width was measured as the middle level of the lesser trochanter (line MN). The canal width was measured as 10 cm below the lesser trochanter (line KL). The calcar-to-canal ratio was calculated as line KL divided by line MN, which was used for the Dorr classification. The femoral offset (FO) was measured as the vertical distance from the center of COR and the ipsilateral anatomical femoral axis (line AB and line FG). The acetabular offset (AO) was measured as the vertical distance from the COR and the vertical line passing through the ipsilateral teardrop (line AC and line FH). The hip offset (HO) was calculated as the sum of FO and AO (line AB + line AC and line FG + line FH). Leg length discrepancy (LLD) was calculated as the difference between the bilateral vertical line from the most prominent part of the trochanter to the transteardrop line (difference of line ED and line JI)