Retrospective analysis of robotic unicompartmental and total knee arthroplasties: patient demographics and outcomes.

Context: With the growing number of robotic knee arthroplasties being performed, new outcomes must be analyzed to provide a database for comparing robotic and nonrobotic surgeries. These results can be utilized in the future to properly assess the significance of utilizing robotic technology in the operating room regarding patient outcomes and cost.

Objectives: The aims of this study are to: (1) analyze adverse outcomes from robotic-assisted knee arthroplasty and its relation to sex, body mass index (BMI), and age; and (2) explore any possible differences in outcomes among robotic-assisted unicompartmental knee arthroplasty (UKA) and robotic-assisted total knee arthroplasty (TKA). It is hypothesized that sex, BMI, and age will play a role in adverse events experienced among robotic-assisted knee arthroplasty. It is hypothesized that adverse outcomes will differ in robotic-assisted TKA v UKA.

Methods: A retrospective analysis was performed utilizing 1,300 patient cases from a single surgeon that underwent robotic-assisted UKA or TKA utilizing a robotic surgical system. Demographics were sorted by age, sex, and BMI. Outcomes were sorted by the type of adverse event. The most common adverse event was further statistically analyzed by age, sex, and BMI and then compared to the total cohort. The most common adverse event was also broken down by TKA vs. UKA.

Results: The average age of the individuals undergoing this procedure was 63.6 years, with 52.3 % being female. The average BMI was 32.2. Of the 87 patients who experienced adverse events, 111 total events were documented. Manipulation under anesthesia (MUA) was the highest experienced adverse event. Among the MUA events, 79.5 % had a BMI over 30 (p=0.067), 72.8 % were female (p=0.014), and the average age was 59 years (p=0.019). Among the MUA adverse events, 76.9 % (n=30) were following a TKA and 23.1 % were following a UKA. When considering the entire sample (n=1,300), there was a statistically significant 12.6 times greater odds that an MUA occurred among those who had a TKA vs. UKA (p<0.001). Similar results were discovered when only considering those who had experienced an adverse event (n=87) because the odds of an MUA occurring among those who underwent a TKA was 4.67 times greater than those who underwent a UKA (p<0.001).

Conclusions: MUA was the most common adverse event in this cohort of robotic-assisted knee arthroplasties. The other adverse events did not yield large enough cohort sizes to analyze statistically in relation to specific patient demographics. Younger patients and females were at significantly greater odds of needing MUA. A BMI over 30 was not found to have a statistically significant risk of needing an MUA after robotic-assisted knee arthroplasty. Among the total cohort, those who underwent a TKA were at a 12.6 times greater odds of needing an MUA than those who received a UKA.