Abstract

Medial unicompartmental knee arthroplasty (MUKA) has become an established treatment option for medial compartment osteoarthritis. While advancements in materials and robotic-assisted surgery have improved outcomes, concerns about long-term survivorship persist. This systematic review and meta-analysis assess failure rates of MUKA based on implant designs, follow-up periods, and surgical techniques.

A systematic review and meta-analysis were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered on the international prospective register of systematic reviews (ID CRD42023479247). Literature searches in PubMed, Cochrane, MEDLINE, and EMBASE included studies from 2016 to 2024. Inclusion criteria were English-language studies reporting MUKA survivorship and failure rates, with a minimum cohort of 20 patients, specifying implant type and surgical technique. Data extraction and analysis were performed by three independent reviewers. Statistical analyses used the Mantel-Haenszel method and random-effects models.

From 159 articles, failure rates across 114,088 knees were 2.7% (95% confidence interval 2.1 to 3.3). Failure rates were 6.3% for fixed bearing all-polyethylene, 1.3% for fixed bearing metal-backed (FB M-B), and 3.0% for mobile bearing metal-backed (MB M-B). Significant differences were noted between fixed bearing all-polyethylene and both FB M-B (P = 0.004) and MB M-B (P = 0.007), but not between FB M-B and MB M-B (P = 0.12). By follow-up duration, failure rates were 0.4% for <5 years, 4.1% for 5 to 10 years, and 8.3% for > 10 years. Robotic techniques had significantly lower failure rates than standard techniques (1.2 versus 2.9%, P = 0.001).

This meta-analysis demonstrates that advanced implant designs improve outcomes for MUKA, while robotic techniques further enhance results. However, variability in survivorship definition, follow-up duration, and lack of differentiation between cemented and uncemented implants remain limitations. Future studies should explore long-term outcomes, refine implant choices, and optimize surgical approaches to enhance MUKA survivorship.