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Published on: May 5, 2023
Influence of Compartment on Outcome and Survivorship in Unicompartmental Knee Arthroplasty in Younger Patients
Ethan Laing1, Gary O'Toole2, Joseph P Queally3
1Department of Clinical Surgery, Trinity College Dublin Medical School, Dublin, Ireland.
Background:
Unicompartmental knee arthroplasty (UKA) is an effective treatment for compartmental osteoarthritis (OA), offering advantages over total knee arthroplasty (TKA), such as faster recovery, fewer complications, and preserved kinematics. However, 10-year to 12-year survivorship and outcome comparisons between medial and lateral UKA remain unclear, especially in younger patient cohorts, for whom there are fewer published data in the peer-reviewed literature.
Methods:
We conducted a retrospective study of 287 consecutive UKAs (161 medial and 126 lateral) performed in patients ≤ 55 years of age by a single surgeon between August 2010 and July 2018. The mean age was 49 years (range, 29 to 55); 67.2% were men, and the mean body mass index was 28.4 (range, 24 to 36). The mean follow-up was 10.2 years (range, seven to 15 years). Outcomes included Kaplan-Meier survivorship (end point: revision to TKA) and functional scores. Statistical analyses used log-rank tests for survivorship, t-tests for continuous variables, and Chi-square for categorical data.
Results:
Overall, 10-year survivorship was 89.3% (95% confidence interval (CI) 85.5 to 93.1). Lateral UKA had superior survivorship (96.8%, 95% CI: 93.2 to 100) compared to medial (83.2%, 95% CI: 76.8 to 89.6; log-rank P = 0.002). Progression of OA in the retained compartment was the primary failure mode (61% of revisions), especially following medial UKA. Functional improvements were excellent, with mean final University California Los Angeles (UCLA) score 8.1 (range, 7 to 9), SF-36 82.1 (range, 72 to 88), and Western Ontario and McMaster Universities (WOMAC) pain 17.2 (range, 13 to 20). Both medial and lateral UKA delivered the same magnitude of improvement.
Conclusions:
Lateral UKA demonstrates outstanding 10-year survivorship, outperforming medial UKA in this cohort, primarily due to lower OA progression rates. Both compartments yield high functional outcomes, with lateral UKA higher, due to higher baseline scores. These results support the use of UKA as a durable option for patients in this age group.
