The reliability of navigation-guided gap technique in total knee arthroplasty

The OrthoPilot TKA navigation system (B. Braun Aesculap, Tuttlingen, Germany) offers software to optimize soft tissue balance using gap balance techniques. However, there are no studies on the reliability of the navigation-guided gap technique. The goal of this study is to establish the reliability of the navigation-guided gap technique. The investigators measured flexion and extension gap in the medial and lateral sides of the knee joint after bone resection to evaluate the reliability of navigation-guided soft tissue balancing. Gap data from 100 cases of navigation-guided total knee arthroplasty were analyzed. We defined trapezoidal gap (unsatisfactory soft tissue balance) as a gap difference < 3 mm between the medial and lateral sides in extension and a 5 mm difference in 90 degrees of flexion. Furthermore, gap difference between flexion and extension greater than 3 mm on the medial side and 5 mm on the lateral side was also considered a trapezoidal gap. Among 100 cases, 84 showed rectangular (acceptable) gap, and 16 showed trapezoidal gap. We also evaluated the correlation between clinical results including range of motion and soft tissue balance as well as characteristics of trapezoidal gap. This study suggests that the navigationguided gap technique is a reliable method for optimizing soft tissue balance.