Comparison of Functional Recovery Between Unicompartmental Knee Arthroplasty and Medial Meniscus Posterior Root Tear Repair in Patients Aged Over 50 Years: A One-Year Propensity Score-Weighted Study.

Abstract

Medial meniscus posterior root tear (MMPRT) accelerates knee osteoarthritis progression. Meniscal root repair (MRR) in patients older than 50 years is controversial due to unpredictable healing and mild to moderate cartilage degeneration, which may lead surgeons to consider unicompartmental knee arthroplasty (UKA). This study compared clinical outcomes of UKA versus MRR in patients older than 50 years who had MMPRT and Kellgren-Lawrence (KL) grade ≤ 3 arthritis. We retrospectively reviewed patients aged 50 to 79 years who had magnetic resonance image (MRI)-confirmed MMPRT who underwent either MRR or mobile-bearing UKA. Patients who had severe medial compartment osteoarthritis (KL-4), varus deformity greater than 5°, or body mass index greater than 35 were excluded. Propensity score weighting balanced baseline demographics. Clinical outcomes-including the Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner activity score, University of California at Los Angeles (UCLA) activity score, and visual analog scale (VAS) for pain-were assessed at six weeks, six months, and one year postoperatively. Unicompartmental knee arthroplasty demonstrated superior outcomes in total KOOS, KOOS symptoms/stiffness, KOOS sport and recreation, and KOOS quality of life from six weeks to one year, as well as VAS pain scores from six months to one year. In the UKA group, total KOOS, KOOS symptoms/stiffness, KOOS pain, and KOOS function exceeded the minimal clinically important difference (MCID) by six weeks and remained above it through one year, whereas the MRR group reached MCID only at six months. Unicompartmental knee arthroplasty also achieved higher Tegner scores at six weeks and higher UCLA scores at six weeks and six months, with no between-group differences at one year. There were two MRR patients (6%) who required conversion to total knee arthroplasty, while no reoperations occurred in the UKA group. In patients older than 50 years who have MMPRT and KL grade ≤ 3, UKA provided faster recovery, greater pain relief, and better functional outcomes than MRR during the first postoperative year and should be considered a reliable treatment option.