Ten-Year Survivorship, Patient-Reported Outcomes, and Satisfaction of a Fixed-Bearing Unicompartmental Knee Arthroplasty

Background: We sought to determine the 10-year survivorship and reasons for revision for a fixed-bearing unicompartmental knee arthroplasty (UKA) design. In addition, we report on patient-reported outcomes and satisfaction and compare results of medial vs lateral compartment UKA and cemented vs cementless UKA with the same design. Methods: We performed a retrospective cohort study on a single-surgeon case series using a single fixed-bearing UKA design in 158 consecutive patients who underwent 177 UKA procedures between July 2000 and December 2010. Cases missing follow-up within the last year, clinically or via telephone, were excluded (n = 17, 10%). A cumulative incidence competing risk model was used to evaluate the cumulative incidence of failure. Results: Cumulative incidence of revision at a mean follow-up of 10 years was 13%. The majority of revisions (43%, 10/23) were for aseptic tibial component loosening, followed by progression of osteoarthritis (5/23, 22%). All Patient Reported Outcomes Measurement Information System measures demonstrated mean T-scores within one standard deviation from the US population norm. The mean Knee Injury and Osteoarthritis Outcome Score for Joint Replacement was 96.9 (range, 40-100). The mean pain score was 3.8 (range, 0-8). Eighty-six percent of patients were satisfied with the UKA. Conclusions: At 10-year follow-up, the most common causes for revision were aseptic tibial loosening and adjacent compartment knee arthroplasty, and similar results were found for medial vs lateral compartment and for cemented vs cementless UKA. Surgeons should consider these findings for future UKA designs, and this represents the first study reporting on survivorship and outcomes of this specific UKA design.