Medial/central PF arthritis and functionally stable ACL deficiency do not compromise outcomes of fixed-bearing medial UKA

BackgroundThere is limited published data assessing functional scores and patient satisfaction following unicompartmental knee arthroplasty (UKA) in patients with patellofemoral (PF) arthritis or anterior cruciate ligament (ACL) deficiency. The purpose of this study was to determine whether medial/central PF arthritis or functionally stable ACL deficiency compromise outcomes of fixed-bearing medial UKA at a minimum follow-up of 2 years. The hypothesis was that equivalent outcomes can be achieved in patients with substantial medial/central PF arthritis or with functionally stable ACL deficiency.MethodsThe authors studied a consecutive series of 229 patients (240 knees) at 36.9 ± 6.3 months after receiving fixed-bearing medial UKA. Patients completed pre- and post-operative (2 years) clinical outcome questionnaires for Oxford Knee Score (OKS), EQ-5D, Knee injury and Osteoarthritis Outcome Score Physical Function Short Form (KOOS-PS), University of California, Los Angeles (UCLA) activity score, and Forgotten Joint Score (FJS). Multivariable analyses were performed to determine associations between clinical scores, patient demographics, PF arthritis and functionally stable ACL deficiency.ResultsOf the 240 knees, 125 (54%) had substantial medial/central PF arthritis and 21 (9%) functionally stable ACL deficiency. Multivariable analyses revealed no association between outcomes and medial/central PF arthritis, but knees with functionally stable ACL deficiency were associated with better KOOS-PS (β = 8.99, p = 0.012).ConclusionFixed-bearing medial UKA grants satisfactory outcomes at 2 years even in knees with substantial medial/central PF arthritis or functionally stable ACL deficiency. Longer-term prospective studies with larger cohorts are needed to confirm these promising findings regarding outcomes in patients traditionally contraindicated for medial UKA.