The Combination of Preoperative Bone Marrow Lesions and Partial-Thickness Cartilage Loss Did Not Result in Inferior Outcomes After Medial Unicompartmental Knee Arthroplasty.

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Abstract

[Indexed for MEDLINE] 15. JB JS Open Access. 2026 Feb 3;11(1):e25.00292. doi: 10.2106/JBJS.OA.25.00292. eCollection 2026 Jan-Mar. A Comparison of the Outcomes of Simultaneous Bilateral and Unilateral Mobile-Bearing Unicompartmental Knee Arthroplasties: An Analysis of Data from the National Joint Registry of England, Northern Ireland and Isle of Man. Mohammad HR(1)(2), Judge A(3), Murray DW(1). Author information: (1)Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford, United Kingdom. (2)Barts Bone & Joint Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom. (3)Musculoskeletal Research Unit, Bristol Medical School, University of Bristol, Level 1 Learning and Research Building, Southmead Hospital, Bristol, United Kingdom. BACKGROUND: Unicompartmental knee arthroplasty (UKA) is an effective treatment for unicompartmental end-stage knee arthritis. Simultaneous bilateral UKAs for patients with bilateral knee arthritis can reduce costs, number of anesthetics, and overall rehabilitation time. It is unknown how the long-term outcomes of unilateral and simultaneous bilateral UKAs compare. METHODS: In total, 1,939 unilateral and 1,939 simultaneous bilateral medial mobile-bearing UKAs (n = 3,878) from the National Joint Registry were propensity score matched. Kaplan-Meier and Cox regression were used to compare implant survival, revision indications, and mortality. RESULTS: The 10-year implant survival in the simultaneous bilateral group was 92% (95% confidence interval [CI] 90-94) and in the unilateral group was 90% (95% CI 88-92). The simultaneous bilateral group had a lower revision risk (hazard ratio [HR] 0.73, p = 0.01). Revisions for pain were lower in the bilateral group (0.5% vs. 1.2%, p = 0.01). There were no differences in patient mortality. Subgroup analyses found similar trends in 10-year implant survival and revision risk with both cementless (simultaneous bilateral 98% CI 95-99; unilateral 95% CI 91-98; HR 0.66, p = 0.27) and cemented fixation (simultaneous bilateral 91% CI 89-93; unilateral 90% CI 88%-92%; HR 0.85, p = 0.28). CONCLUSIONS: Simultaneous bilateral UKAs had better 10-year implant survival and similar mortality to compared with single-unilateral UKAs. For patients with severe symptomatic bilateral unicompartmental knee osteoarthritis, simultaneous bilateral UKAs could be considered to be a safe and effective procedure, particularly as only one operation and postoperative recovery is required. LEVEL OF EVIDENCE: Level IV. See Instructions for Authors for a complete description of levels of evidence. Copyright © 2026 The Authors. Published by The Journal of Bone and Joint Surgery, Incorporated. All rights reserved. DOI: 10.2106/JBJS.OA.25.00292 PMCID: PMC12854667