Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

BACKGROUND: Unicompartmental knee replacement (UKR) offers advantages over total knee replacement but has higher revision rates. New instrumentation known as Microplasty was introduced to address this. The aim was to compare the revision rates of UKRs implanted with Microplasty and traditional instrumentation (Non-Microplasty). METHODS: National Joint Registry (NJR) data was used to propensity score match 15,906 UKRs (7953 Microplasty and 7953 Non-Microplasty) for important patient, implant and surgical factors. Implant survival rates were determined using the Kaplan-Meier method and compared using Cox regression models in a multilevel model. RESULTS: The five-year implant survival for Microplasty and Non-Microplasty UKRs were 96.7% (95% CI: 96.0%-97.2%) and 94.5% (CI: 93.8-95.1%), respectively. The revision rate for Microplasty UKR was significantly lower than that of Non-Microplasty UKRs (hazard ratio [HR] = 0.77, p = 0.008). Compared with Non-Microplasty UKRs, the revision rate of Microplasty UKRs implanted during the year after the introduction of Microplasty was lower, but the difference was not significant (HR: 0.86, CI: 0.67-1.10, p = 0.23), whereas for those implanted more than a year after introduction, the difference was significant (HR: 0.69, CI: 0.54-0.89, p = 0.004). CONCLUSION: The use of Microplasty instrumentation has resulted in an improved five-year UKR survival. Microplasty UKR implanted during the first year after introduction had a small, non-significant decrease in revision rate. As the revision rate did not increase, this suggests that there is no adverse learning curve effect. Microplasty UKRs implanted after this transition period had a revision rate 31% lower than the Non-Microplasty group. LEVEL OF EVIDENCE: II.

Original publication




Journal article



Publication Date





993 - 1002


Microplasty, Non-Microplasty, Unicompartmental knee arthroplasty