Comparative Outcomes of Patello-Femoral and Unicompartmental Knee Arthroplasty: A Propensity-Matched Analysis at Two, Five, and 10 Years.

INTRODUCTION: Patello-femoral arthroplasty (PFA) and unicompartmental knee arthroplasty (UKA) are established treatments for isolated patello-femoral or single-compartment knee arthritis. The durability of modern PFA relative to UKA remains incompletely defined, particularly with respect to reoperation and conversion to total knee arthroplasty (TKA) at two to 10 years of follow-up. The purpose of this study was to compare two-, five-, and 10-year outcomes following PFA and UKA using a large multi-institutional database. METHODS: A retrospective cohort study was performed using a national database. Patients undergoing PFA or UKA were identified using Current Procedural Terminology (CPT) codes and propensity matched 1:1 for age, sex, body mass index (BMI), race, and medical comorbidities. Surgical outcomes were evaluated at two, five, and 10 years. After matching, 978 patients remained in each cohort at two years, 635 patients remained in each cohort at five years, and 226 patients remained in each cohort at 10 years. Postoperative infection was defined using International Classification of Diseases, Tenth Revision (ICD-10) codes for infection following a procedure (T81.4), disruption of wound (T81.3), pyogenic arthritis (M00), and direct infection of joint (M01). RESULTS: Subsequent knee arthroscopy occurred at higher rates following PFA at two years (7.3% PFA versus 2.9% UKA, P < 0.001) and five years (10.4% PFA versus 5.5% UKA, P = 0.001). Revision occurred at higher rates following PFA at 10 years (14.2 versus 8.0%, P = 0.041). There was no difference in postoperative infection or conversion to TKA, and Kaplan-Meier analysis demonstrated similar implant survivorship. Rates of arthroscopy for meniscectomy were similar between groups. CONCLUSION: In this large propensity-matched analysis, PFA demonstrated significantly higher rates of arthroscopy compared to UKA, with comparable implant survivorship and conversion to TKA at up to 10 years. These findings suggest that while survivorship is equivalent, PFA may carry a higher burden of secondary procedures, which should be considered in surgical decision-making.