Precision of preoperative digital templating in total hip arthroplasty.

The purpose of the present study was to evaluate the precision of digital templating in total hip arthroplasty (THA) and the influence of the surgeons' level of experience on the accuracy of preoperative planning. A retrospective review of digital computer planned THA's was performed on 169 hips. The preoperatively planned component sizes were compared to the sizes used in the operation. An exact agreement between planned and actually used size was achieved in 33.7% of the hips for the acetabular cups and 36% for the femoral stems. A prediction of +/- 1 size was reached in 77.5% for acetabular components and 82.3% for the femoral stem. On average, the acetabular components were planned approximately 0.9 sizes too large, the femoral stems 0.3 sizes too small. The accuracy of preoperative planning showed no differences according to the level of training of the planning surgeon. We state that the digital templating is useful to predict the implant size. However, 15 of the 169 planned components showed a difference of more than 2 sizes. Therefore, digital templating cannot fully replace intraoperative X-ray use.