More Technology, but Similar Early Safety: Robotic Versus Conventional Unicompartmental Knee Arthroplasty, a 30-Day Outcome National Database Study.

Abstract

Robotic assistance in unicompartmental knee arthroplasty (UKA) has been increasingly adopted, but evidence regarding early safety remains constrained by heterogeneities and limitations such as Current Procedural Terminology (CPT) code layering designs, smaller sample sizes, and baseline imbalances. Accordingly, this study compares short-term (30-day) adverse events and outcomes between robotic UKA (R-UKA) and conventional UKA (C-UKA) using a propensity-matched, uniformly-defined cohort. A national database (2022-2024) was queried for patients undergoing UKA using CPT 27446. R-UKA and C-UKA were distinguished using the dedicated National Surgical Quality Improvement Program (NSQIP) "robot use" variable. Cases with missing key entries or complexity-amplifying add-ons were excluded. Propensity score matching (1:2) balanced baseline covariates (all standardized mean differences less than 0.1), yielding 727 R-UKA and 1,454 C-UKA matched cases. The primary outcome was any 30-day postoperative adverse event (AAE), supplemented by secondary complication-stratifying analyses. Statistics included independent t-tests, Chi-squares, and exploratory multivariable regressions with odds ratios. The R-UKAs were associated with longer operative times (86.1 ± 34.7 versus 78.9 ± 35.5 minutes; P < 0.001), shorter lengths of stay (0.4 ± 0.8 versus 0.6 ± 1.1 days; P < 0.001), and were more often performed outpatient (92.2 versus 80.9%; P < 0.001). The rates of AAEs were similar between R-UKA and C-UKA procedures (3.4 versus 2.1%, respectively), as were rates of major (1.7 versus 0.9%), minor (2.1 versus 1.4%), and infectious (2.6 versus 1.5%) complication subgroupings (all P > 0.05). Chronic obstructive pulmonary disease was the sole significant predictor of AAE, observed only in the R-UKA cohort (odds ratio = 9.442; P = 0.002). Using standardized identification and propensity matching, R-UKA was associated with longer operative times and shorter stays compared with C-UKA, though without any clear or consistent reductions in 30-day adverse events. Future, longitudinal research is needed to corroborate findings.