Background

Total hip arthroplasty requires proper sizing and placing of implants to ensure excellent outcomes and reduce complications. Calculation of femoral offset is an important consideration for optimal reconstruction of the hip biomechanics. Femoral offset can be measured on plain films or with flouroscopy if the x-ray beam is perpendicular to the plane determined by the angle between the neck axis and femoral shaft axis. This distance is evident only with the femur in the correct degree of rotation. Though pre-operative templating for femoral component size and offset is a regular accepted practice, a consistent method for assessing correct femoral rotation on the AP x-ray view has not been established.