Primary hip arthroplasty templating on standard radiographs. A stepwise approach.

In the past decade, the indications for hip replacements broadened and media induced patients' expectations in terms of function and longevity have been rising steadily. Improved technology addressed wear and fixation issues. However, more attention should be given to optimising hip biomechanics as this is essential to restore function. Pre-operative hip templating allows anticipating the correct implant position and potential difficulties prior to surgery. As such it is an essential part of the implantation process. We propose a four-step approach for hip templating on a standardised standing pelvic radiograph: 1. Identify anatomical landmarks (the medullary canal, the greater and lesser trochanter, the acetabular roof and the teardrop); 2. Assess the quality of the radiograph (femoral rotation, pelvic inclination and symmetry); 3. Identify mechanical references (the original acetabular and femoral rotation centre, the femoral and acetabular offset and the leg length and hip length discrepancy); 4. Optimise implant positioning to restore hip biomechanics. Hip templating helps recognising "difficult hips" where restoration of the original hip anatomy is no option. These hips should be approached carefully with a well defined pre-operative plan to minimise the chances of complication while maximising hip function. Although it is mainly under these circumstances that hip templating is a major asset, we believe that performing systematically a standardised preoperative templating should contribute to improved hip arthroplasty function and outcome.