Comparing clinical and patient-reported outcomes between robot-assisted and conventional unicompartmental knee arthroplasty

Background: Robot-assisted (RA) unicompartmental knee arthroplasty (UKA) has been associated with improved implant alignment and accuracy compared to conventional UKA; however, it is unclear if this translates to improved outcomes. The aim of this study was to compare short-term clinical and functional outcomes between RA and conventional UKA. Methods: A retrospective review of primary UKAs performed by a single surgeon from 2002 to 2021 was conducted using the institution's electronic health records and outcomes database. Outcomes included 90-day complications, cumulative revisions, implant survivorship, and patient-reported outcome measures (PROMs). Oxford Knee Scores (OKS) and SF-12 physical and mental were compared using a mixed-effect regression model. A Kaplan-Meier curve was plotted to illustrate survivorship using revision as the endpoint. Results: A total of 397 cases were included (RA: n=85; conventional: n=312). The RA group had significantly more men (P<0.01) and a lower median BMI (P=0.02). Age and comorbidities were similar between groups (P>0.05). There was no difference in the rates of 90-day complications (RA: n=0, 0% vs. conventional: n=1, 0.9%, P=1). Significantly fewer cumulative revisions occurred in the RA group (RA: n=0, 0% vs. conventional: n=18, 5.8%; P=0.02). The median lengths of follow-up for RA and conventional UKA were 772 and 5,393 days, respectively. Both techniques showed within-group improvement in OKS and SF-12 physical through 2 yr (P<0.01). No between-group differences in PROMs occurred at any time point. Conclusions: Medial, fixed-bearing RA UKA shows no compromise in patient safety or outcomes when compared to conventional UKA through early-term follow-up.