Manipulation Under Anesthesia Rates in Technology-Assisted versus Conventional-Instrumentation Total Knee...

Various technological advancements, specifically robotic assistance, have been implemented for total knee arthroplasty (TKA) procedures to attempt to improve patient outcomes and decrease complication rates. Manipulations under anesthesia have been considered a surrogate for knee stiffness, an undesired postoperative outcome that can potentially be avoided. Currently, there is a lack of information regarding the impact that these new technologies have on manipulations under anesthesia (MUA) rates following TKA. Therefore, the purpose of this study was to evaluate rates of MUAs between a consecutive series of patients who underwent robotic-assisted surgery compared to patients who underwent TKA with conventional instrumentation.

A total of 188 consecutive robotic-assisted total knee arthroplasties were performed by five fellowship-trained, high-volume surgeons at academic and community institutions. Patients were paired to a consecutive equal number of control patients by each of the specific surgeon for comparison. All patients followed similar postoperative rehabilitation starting on postoperative day one. Rates of MUAs were evaluated within and between cohorts. Additionally, the percent difference of rates was calculated to compare cohorts. All patients were evaluated at a minimum of two years follow-up time from the index procedure. Chi-square analyses was performed to statistically compare MUA rates between the cohorts.

The overall manipulation under anesthesia rate for the study cohort was 1.06% (2/188 patients), while it was 4.79% in the control cohort (9/188) (p=0.032). A 127.5% difference in manipulation under anesthesia rates was found between the two cohorts. No individual surgeons had higher MUA rates in their robotic-assisted group.

Our study found that patients undergoing robotic-assisted TKA experienced a significant, 4.5-fold decrease in rates of manipulation under anesthesia (p=0.032). Given that MUAs can be a marker of knee stiffness following total knee arthroplasty, the lower rate indicates that study cohort patients had less knee stiffness and, therefore, greater initial postoperative range of motion than the control cohort. Based on these data, assistive technologies may have an advantageous role contributing to enhanced patient outcomes.