TOPLINE:

Among individuals with medial compartment knee osteoarthritis, those who underwent partial knee replacement demonstrated clinical outcomes and rates of reoperation and revision comparable to those who underwent total knee replacement over 10 years, while offering greater cost-effectiveness.

METHODOLOGY:

• Researchers conducted a follow-up study of a randomized controlled trial (TOPKAT) that included 528 patients with isolated osteoarthritis of the medial compartment of the knee (mean age, 65 years; 58% male) from 27 secondary care hospitals in the UK (2010-2013).
• Patients were randomly assigned to receive either partial knee replacement (n = 264) or total knee replacement (n = 264), performed by surgeons who were either experts in both procedures or had specific expertise in the allocated procedure. The clinical outcomes and cost-effectiveness of the two techniques were compared.
• Participants were followed annually for 5 years and again at years 7 and 10, with clinic-based assessments during the first 5 years and data on patient-reported outcomes collected thereafter.
• The endpoint of this follow-up study was the Oxford Knee Score at 10 years post-randomization.
• Secondary outcomes included quality-adjusted life years (QALYs), cost-effectiveness, and rates of complications, reoperations, and revisions.

TAKEAWAY:

• At 10 years, no significant difference in the Oxford Knee Score was found between the partial knee replacement and total knee replacement groups (P = .78). Patient satisfaction also did not differ between groups.
• The rate of complications was lower in the partial knee replacement group than in the total knee replacement group in the intention-to-treat analysis (21% vs 29%; risk ratio, 0.73; P = .016). At the 10-year follow-up, deaths were reported in 10% and 11% of patients in the partial and total knee replacement groups, respectively.
• The proportions of patients who underwent reoperations or revisions were comparable between groups over 10 years, with reasons for revision including unexplained pain noted in both groups and bearing dislocation noted only in the partial knee replacement group.
• Partial knee replacement was less expensive than total knee replacement, with a mean difference in costs of -£731 (95% CI, -1352 to -110) and a 97% probability of being cost-effective at £20,000 per QALY.

IN PRACTICE:

“This 10-year randomized controlled trial data provides the strongest, most robust evidence yet about the relative merits of [total knee replacement] and [partial knee replacement]. There were no significant differences between implants in clinical outcomes, reoperations, or revisions. However, the lower complication rate and the dominant health economic findings support continued recommendation for [partial knee replacement],” the authors of the study wrote.

SOURCE:

The study was led by David J. Beard, DPhil, University of Oxford, Oxford, England. It was published online on November 18, 2025, in The Lancet Rheumatology.

LIMITATIONS:

The selective nature of the trial may limit the generalizability of the results. Younger, high-demand patients who could benefit more from partial knee replacement may have been excluded. The long duration of the study also raises concerns because there may have been improvements in the devices and techniques over time.

DISCLOSURES:

The study was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme. Four authors disclosed receiving research grants or investigator awards or being members of the NIHR. Two authors declared receiving grants, consulting fees, or royalties from Zimmer Biomet, and another author reported serving as a board member of the Royal College of Surgeons of England and the University of Bristol, Bristol, England, and holding a patent.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.