Intraoperative Dynamic Planning with Robotics Improves Patellar Tilt following Primary Total Knee Arthroplasty

Introduction Anterior knee pain remains a commonly reported complaint following total knee arthroplasty (TKA) and has been shown to correlate to the patella as a source. While robotic knee systems have been shown to improve femoral and tibial component accuracy, the impact of robotics on patella tracking and tilt has not been adequately studied. Therefore, we sought to compare patellar tilt in robotic and conventional TKA. Methods We retrospectively reviewed 602 consecutive primary TKAs by a single surgeon over a 4-year period. The population was divided into two cohorts: robotic vs. conventional. Patellar tilt was measured using merchant view radiographs. Chi-square tests were used to examine for differences between categorical variables and t-tests for continuous variables. Binary logistic regression was used to control for differences between cohorts. Results A total of 260 robotic knees and 311 conventional knees were included. There were no differences in demographics between groups. A binary logistic regression showed no significant association between decreasing patellar tilt and a lack of patellar resurfacing (p = 0.217, Odds Ratio = 1.045, 95% CI = 0.974-1.121). Using the absolute value, the mean patellar tilt in the robotic cohort was 1.96° compared to 2.89° of tilt in the conventional cohort (p = 0.0001). The percentage of outliers where the patellar tilt exceeded 3 degrees from neutral was significantly higher among conventional cohort (34% vs 20%, p=0.00018). WOMAC Pain scores were significantly improved in the robotic vs nonrobotic cohort (16.6 vs 15.0, p < 0.001). Conclusion Robotic TKA leads to an improvement in patellar tilt, with a smaller percentage of outliers, compared to conventional TKA. These findings could partially explain the improved pain with robotic TKA.