Comparison of analog 2D and digital 3D preoperative templating for predicting implant size in total knee arthroplasty

The aim of this study was to compare the accuracy of preoperative templating in total knee arthroplasty (TKA) using conventional two-dimensional (2D) and computed tomography (CT)-based three-dimensional (3D) procedures, and to confirm the necessity of 3D evaluation for preoperative planning. One hundred consecutive primary TKAs were analyzed. Preoperative templating was performed for each TKA using both conventional 2D radiographs and a CT-based 3D image model created using KneeCAS software. Accuracies with regard to the predicted and actual implant sizes were determined for each procedure. The 3D procedure was found to be more accurate (59%) than the 2D procedure (56%) in predicting implant size, but the difference was not statistically significant (p = 0.67). Computer-assisted surgery systems are often used for preoperative planning in TKA. However, our results do not support the superiority of 3D preoperative templating over 2D conventional evaluation in predicting implant size. Thus, 3D templating may not be necessary for preoperatively predicting implant size in TKA, and can only be used as an approximate guide.