Comparable Survivorship and Patient-Reported Outcomes Following Unicompartmental Knee Arthroplasty in Obese and...

The influence of obesity on outcomes after unicompartmental knee arthroplasty (UKA) remains controversial. This systematic review evaluated whether obesity affects survivorship, reasons for revision, and patient-reported outcome measures (PROMs) following UKA.

MEDLINE, EMBASE, and CENTRAL were searched from inception to October 15, 2025. Eligible studies reported UKA outcomes stratified by body mass index (BMI), including cohorts exclusively composed of obese patients (BMI ≥ 30). Less than 5-year), five to less than 10-year, and ≥ 10-year survivorship was compared across nonobese (BMI less than 30), obese (BMI 30 to less than 40), and morbidly obese (BMI ≥ 40) patients using meta-analysis. Secondary outcomes included reasons for revision and PROMs. There were 27 studies (27,271 knees) included (mean age, 65 years; mean BMI, 30.7).

Less than 5-year survivorship for nonobese, obese, and morbidly obese groups was 95.5, 95.3, and 95.8%, respectively (P = 0.943). The five to less than 10-year survivorship was 95.3, 92.1, and 90.6%, respectively (P = 0.034), with adjusted pairwise comparison demonstrating a nonsignificant trend toward lower survivorship in morbidly obese patients compared to nonobese (adjusted P = 0.065). The ≥ 10-year survivorship was 92.1, 92.9, and 88.7%, respectively (P = 0.460). The most common causes for revision were aseptic loosening (47.0%), pain without loosening (16.2%), and progression of osteoarthritis (15.2%). Morbidly obese patients demonstrated higher rates of progressive osteoarthritis and technique-related failure. The PROMs improved across all BMI categories, with slightly lower scores in obese and morbidly obese individuals.

Obesity should not be considered an absolute contraindication to UKA. Obese patients achieve substantial functional improvement and demonstrate survivorship comparable to nonobese patients across less than 5-years, five to less than 10-years, and ≥ 10-years follow-up. Morbidly obese patients more often required secondary surgery for progression of arthritis, a modifiable risk factor that can inform individualized preoperative counseling and risk mitigation strategies.

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