Computer Assistance Increases Precision of Component Placement in Total Knee Arthroplasty with Articular Deformity

Background The accuracy of computer navigation applied to total knee arthroplasty (TKA) in knees with severe deformity has not been studied.

Questions/purposes The purpose of this study was to compare the radiographic alignment achieved in total knee replacements performed with and without navigation and to search for differences in the final alignment of two groups of patients (with and without previous joint deformities) using the same system of surgical navigation.

Methods The first series comprised 40 arthroplasties with minimal preoperative deformity. In 20 of them, surgical navigation was used, whereas the other 20 were performed with conventional jig-based technique. We compared the femoral angle, tibial angle, and femorotibial angle (FTA) by performing a post-TKA CT of the entire limb. In the second series, 40 additional TKAs were studied; in this case, however, they presented preoperative deformities greater than 10° in the frontal plane.

Results The positioning of the femoral and tibial component was more accurate in the group treated with surgical navigation and FTA improvement was statistically significant. When comparing the results of both series, FTA precision was always higher when using computer-assisted surgery. As for optimal FTA, data showed the use of surgical navigation improved the results both in the group with preoperative deformity greater than 10° in the frontal plane and in the group with minimal preoperative knee deformity.

Conclusions Surgical navigation obtains better radiographic results in the positioning of the femoral and tibial components and in the final axis of the limb in arthroplasties performed on both deformed and more normally aligned knees.

Level of Evidence Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.