Robotic Total Knee Arthroplasty is Associated with Earlier Return of Postoperative Range of Motion

Introduction: Postoperative range of motion (ROM) is an important measure for the functional outcome and overall success after total knee arthroplasty (TKA). While robotic knee systems have been shown to reduce pain and improve early function, the return of postoperative ROM specifically has not been adequately studied. The purpose of this study was to compare postoperative ROM in robotic and conventional TKA. We hypothesized that robotic TKA leads to an improvement in postoperative ROM. Materials and Methods: A retrospective cohort study of 674 primary TKAs by a single surgeon between January 2018 and February 2023 was completed. Patients that did not have both a two-week follow up and eight-week follow up were excluded. Revision/conversion TKAs were excluded. The population was divided into two cohorts based on technique utilized: robotic versus conventional. Preoperative extension/flexion data, postoperative extension/flexion data at two-week and eight-week follow ups, and manipulation under anesthesia data were collected. ROM was defined as flexion minus extension. Chi-square tests were used to examine for differences between categorical variables and t-tests for continuous variables. Results: A total of 307 robotic and 265 conventional knees were included. There were no differences in demographics, mean follow up, or preoperative ROM between groups. The robotic group had significantly more flexion (99.20° vs. 96.98°; p=0.034) and ROM (97.81° vs. 95.56°; p=0.047) at the two-week follow up. The loss in ROM at the two-week follow up from preoperative ROM was significantly less for the robotic group (-11.21° vs. -14.16°; p=0.031). There were no significant differences in extension at either follow up, in flexion at the eight-week follow up, or in ROM at the eight-week follow up. Conclusion: Robotic TKA leads to an improvement in postoperative flexion and ROM when compared to preoperative ROM at two-week follow up. These findings could partially explain the quicker recovery associated with robotic TKA.