Correlation of revision rate of unicompartmental knee arthroplasty with total knee arthroplasty: a meta-analysis of clinical studies and worldwide arthroplasty registers.

Introduction: The purpose of this study was to elucidate differences and similarities in revision rates amongst studies and national registers featuring total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA). Thereby comparability and reproducibility between study and register findings should be created.

Materials and methods: Clinical studies published between 2004 and September 2023 involving TKA or UKA were reviewed for total arthroplasty numbers, revision rates and demographic data. Findings were calculated as "revisions per 100 component years (CY)" and divided according to the nationality of the center. National arthroplasty registers were searched for numbers of arthroplasties and revisions alongside with demographic data. Revision rates in registers were compared to one another and comparison to revision rates from collected studies was drawn.

Results: After evaluation, 98 studies and seven registers met our inclusion criteria and were included in this study. Cumulative percent revision rate in studies was 3.35% after a mean follow-up of 5.7 years, corresponding to 0.71 revisions per 100 CY for TKA and 7.67% after a mean follow-up of 4.9 years, corresponding to 1.3 revisions per 100 CY for UKA. Registers showed mean overall revision rates of 5.63% for TKA and 11.04% for UKA.

Conclusions: A positive correlation of revision rates of TKA and UKA in studies and registers was found, with overall revision rates of UKA comparted to TKA being 2.29 times higher in clinical studies and 1.96 times higher in registers. Revision rates in registers were 1.56 times higher than presented in clinical studies.