FIXED-BEARINGS, HIGHER SURGEON VOLUME, AND ROBOTICS CONFER IMPROVED SURVIVORSHIP IN UNICOMPARTMENTAL KNEE ARTHROPLASTY: AN ANALYSIS FROM THE AMERICAN JOINT REPLACEMENT REGISTRY

Introduction Unicompartmental knee arthroplasty (UKA) survivorship is influenced by patient selection, implant design, surgeon volume, and surgical technique. We compared UKA implant survivorship reported to the American Joint Replacement Registry (AJRR) stratified by bearing type (fixed or mobile-bearing), surgeon volume, and surgical technique (robotic-assisted (raUKA) or jig-based (jbUKA)). Methods AJRR and Centers for Medicare and Medicaid Services claims data from 2012–2024 were merged. Patient demographics, surgical technique, bearing surface, implant manufacturer, and surgeon annual UKA volume were recorded. Kaplan-Meier survivorship curves were produced with time-dependent Cox Proportional Hazards models. Surgical technique analyses were adjusted for age, sex, and CCI and surgeon volume and excluded cementless and mobile bearing devices. Results 101,468 UKA procedures were reviewed. Mobile bearings (HRs 1.2-1.7), lower annual surgeon volume (HRs 1.2-1.6), and jig-based surgical techniques (HR 1.45) were associated with higher UKA implant cumulative percent revision rate (CPR). Robotic assistance in UKA has increased over time and varies by manufacturer in the United States. Device-specific UKA survivorship demonstrated two implants with better CPR and two with lower CPR compared with the aggregate cohort. Discussion Improved UKA survivorship was associated with fixed bearings, higher annual surgeon volume, and one robotic-assisted surgical platform. Limitations in the volume of other raUKA systems and with AJRR robotics data capture precluded analysis of other raUKA systems. Further study is needed to evaluate the impact of each specific robotic platform on UKA survivorship to avoid data camouflage.