Comparison of manipulation rates for robot-assisted, customized, and conventional total knee arthroplasty: a retrospective cohort study

Background: With projected increases in total knee arthroplasties (TKA), patient outcomes without complications are essential. Arthrofibrosis, a potential complication after TKA that may impact long-term patient outcome, may be remedied by manipulation under anesthesia (MUA); however, it is not risk-free. This study investigated the association between manipulation and newer implants and sophisticated techniques, which hold promise for preventing arthrofibrosis and improving patient outcomes. Methods: The authors retrospectively reviewed 1260 primary knee arthroplasty cases (717 conventional, 217 customized, and 326 robot-assisted) performed by an orthopaedic surgeon from January 1, 2016 to May 31, 2020. Patient records were reviewed for manipulation and demographics (type of implant, sex, body mass index [BMI], smoking status, and prior surgery). Results: Overall manipulation rate was 1.3% (n=17). Manipulation rates for conventional customized and robot-assisted TKAs did not vary significantly (1.84%, n=6; 0.46%, n=1; 1.39%, n=10, respectively; P=0.466). Multivariable logistic regression showed no statistically significant difference in the odds of manipulation depending on the type of implant. However, those who smoked were 4 times more likely to have a manipulation (OR: 4.187, 95% CI: 1.119 to 15.673) when controlling for covariates (type of implant, sex, BMI, and prior surgery). Additionally, those with prior surgery were 2.8 times as likely to have a manipulation (OR: 2.808, 95% CI: 1.039 to 7.589) when controlling for covariates. Conclusions: There were no statistically significant differences in manipulation rates among conventional, customized, and robot-assisted TKAs. However, current smoking status and prior surgery were associated with higher risk of manipulation. Level of Evidence: Level III.