Accuracy and Reliability of Preoperative On-screen Templating Using Digital Radiographs for Total Hip Arthroplasty

PURPOSE Preoperative on-screen templating is a method of using acetate templates on digital images. The aim of the present study was to evaluate the accuracy, intra- and interobserver reliabilities of preoperative on-screen templating using digital radiographs for total hip arthroplasty (THA). MATERIALS AND METHODS Two hundred patients with hip disease who were treated with primary cementless THA were retrospectively evaluated. The accuracy of on-screen templating was assessed by comparing the predicted prosthesis sizes with the actual sizes used operatively. The inter- and intraobserver reliabilities of the templating results were also evaluated. RESULTS The prosthesis prediction accuracy within ±one size was 96.6% for the cup size and 97.8% for the stem size. The inter- and intraobserver reliabilities for the implant size were substantial (kappa>0.70). The intra- and interobserver reliabilities for the leg length discrepancy and femoral offset difference using the intraclass correlation coefficient ranged from 0.89 to 0.97. CONCLUSION Preoperative on-screen templating using digital radiographs showed substantial accuracy and reliability for implant prediction. It is an effective method for predicting the size of implant, correcting the leg length discrepancy and restoring the femoral offset.