Proximal femoral anatomy in total hip arthroplasty. A tri-planar computed tomographic assessment.

The relationship between the tip of the Greater Trochanter (GT) and the centre of the Femoral Head (FH) is commonly used as reference point to align the femoral component during hip arthroplasty. We performed tri-planar computed tomography analysis of the proximal femoral anatomy in a series of 150 patients (n = 150) to accurately delineate this relationship. The mean location for the centre of the FH was 8.64 mm (95% confidence interval, 9.44-7.83) distal to the tip of the GT. The centre of the FH was found to be distal to the tip of the GT in 90.6% of cases. Hence we would suggest caution in using the tip of the GT as a reference point during total hip arthroplasty as it could be associated with an inadvertent intraoperative leg lengthening.