Cemented mobile-bearing medial unicompartmental knee arthroplasty provides long-term implant survival and sustained functional performance in young and active patients aged 60 or below.

PURPOSE

To evaluate long-term outcomes of cemented, mobile-bearing medial unicompartmental knee arthroplasty (UKA) in patients aged 60 or younger, focusing on implant survival, functional results, patient-reported outcome measures (PROMs), and radiographic findings over >10 years.

METHODS

This retrospective single-centre study included 119 knees (102 patients). Implant survival was evaluated using Kaplan-Meier analysis. PROMs included the Oxford Knee Score (OKS), American Knee Society Score (AKSS), UCLA Activity Score and Visual Analogue Scale (VAS). Assessments were performed preoperatively, at mid-term (2-10 years), and at long-term follow-up (>10 years). OKS and AKSS were analysed in relation to Patient Acceptable Symptom State (PASS) thresholds. Radiographs were graded using the Kellgren-Lawrence classification to evaluate lateral osteoarthritis (LOA) progression.

RESULTS

The implant survival rate was 86.7% (95% CI: 78.5-91.9%) at 15 years, and 81.7% (95% CI: 71.4%-88.5%) at 17.5 years. Revision surgery was required in 18 knees (mean time to revision: 8.7 years), primarily due to progression of LOA. All PROMs improved significantly from baseline to the final follow-up (mean: 16 years; p < 0.0001). Although minor functional declines occurred between mid- and long-term follow-ups, these were not statistically significant (p > 0.05), except for functional AKSS. At the final assessment, 96% of patients exceeded the PASS threshold for OKS, 84% for AKSS objective, and 80% for AKSS functional scores. Radiographic LOA progression was frequent but did not significantly impair functional outcomes.

CONCLUSIONS

Cemented mobile-bearing medial UKA in patients aged ≤60 years demonstrated high long-term implant survival and sustained functional benefit. Even in the presence of radiographic LOA progression, clinical outcomes remained excellent. UKA represents a durable and effective treatment for younger patients with isolated medial compartment osteoarthritis.

LEVEL OF EVIDENCE

Level IV.