JOA - 2026-08-26 - Journal Article
Clinical Outcomes of Fixed-Bearing Lateral Unicompartmental Knee Arthroplasty: A Retrospective Cohort Study With Up to 22-Year Follow-Up.
Tsikopoulos K, Kazamias K, Babis G, Smith JRA, Porteous AJ, White P, Davies DH, Murray J, Bristol Knee Group is a collective authorship for:
Topics
Key Takeaway
Fixed-bearing lateral UKA achieved 87% implant survivorship at 20 years with a mean OKS improvement of 19.75 points at 5 years in 113 knees.
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Summary
This single-institution retrospective study evaluated clinical outcomes and survivorship of fixed-bearing lateral UKA in 113 knees performed between 2004 and 2014. Kaplan-Meier analysis demonstrated survivorship of 97% at 5 years, 93% at 10 years, 89% at 15 years, and 87% at 20 years. OKS improved from 17.61 preoperatively to 37.36 at 5 years (mean difference 19.75, 95% CI 16.84–22.66, p<0.001), with survivorship unaffected by sex, laterality, or age.
Key Limitation
The 20-year survivorship estimate is based on a limited number of patients at risk, making the long-term Kaplan-Meier tail statistically unreliable.
Original Abstract
INTRODUCTION
Lateral compartment osteoarthritis (OA) of the knee represents a relatively uncommon clinical entity, accounting for approximately 5 to 10% of patients presenting with symptomatic unicompartmental arthritis. This retrospective study assessed clinical outcomes, complications, and implant survivorships of lateral unicompartmental knee arthroplasty (UKA).
METHODS
In this single-institution retrospective study, data from 113 fixed-bearing lateral UKAs in 108 patients who had a mean follow-up of 13.7 years (range, 0.5 to 22) were analyzed. The mean age of the participants was 64 years (range, 36 to 91). All arthroplasties were performed between 2004 and 2014 in patients who were diagnosed with advanced lateral compartment knee OA. The primary outcome measure was the implant survivorship. The secondary outcome measures included the Oxford Knee Score (OKS, 0 low to 48 high) assessed preoperatively and at one, two, and five years postoperatively, in addition to all-cause mortality.
RESULTS
With survival data from 113 knees in 108 patients included in a Kaplan-Meier analysis, the estimated implant survivorship was 97% at five years, 93% at 10 years, 89% at 15 years, and 87% at 20 years, with 20-year data based on a limited number at risk. The survival distribution did not differ by sex (P = 0.677), laterality (P = 0.761), or age (P = 0.558). The preoperative and five-year OKS were 17.61 (7.46) and 37.36 (10.5), respectively. The mean difference in Oxford Knee Score between the preoperative and five-year postoperative measurements was 19.75 (95% confidence interval [CI] 16.84 to 22.66; P < 0.001). There were 31 deaths from any cause in this series of patients, with none attributed to the index procedure.
CONCLUSIONS
Fixed-bearing lateral UKA appears to be a safe and effective option for patients who have isolated unicompartmental lateral knee osteoarthritis. Excellent survivorship was demonstrated for patients treated with this lateral UKA.