Bearing design influences short- to mid-term survivorship, but not functional outcomes following lateral unicompartmental knee arthroplasty: a systematic review
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To determine survivorship and functional outcomes of fixed and mobile-bearing designs in lateral unicompartmental knee arthroplasties (UKA).
Medline, EMBASE and Cochrane databases were searched. Annual revision rate and functional outcomes were assessed for both fixed and mobile-bearing designs.
A total of 28 studies, of which 19 fixed-bearing and 9 mobile-bearing, representing 2265 lateral UKAs were included for survivorship and functional outcome analyses. The mean follow-up of fixed and mobile-bearing studies was 7.5 and 3.9 years, respectively. Annual revision rate of fixed-bearing designs was 0.94 (95% CI 0.66–1.33) compared to 2.16 (95% CI 1.54–3.04) for mobile-bearing. A subgroup analysis of the domed shaped mobile-bearing design noted an annual revision rate of 1.81 (95% CI 0.98–3.34). Good-to-excellent functional outcomes were observed following fixed and mobile-bearing lateral UKAs; no significant differences were found.
Mobile-bearing lateral UKAs have a higher rate of revision compared to fixed-bearing lateral UKAs with regard to short- to mid-term survivorship; however, the clinical outcomes are similar. Despite the introduction of the domed shaped mobile-bearing design, findings of this study suggest fixed-bearing implant design is preferable in the setting of isolated lateral osteoarthritis (OA). This systematic review was based on low to moderate evidence, therefore, future registry data are needed to confirm these findings. However, this study included a large number of patients, and could provide information regarding risk of revision and functional outcomes of mobile and fixed-bearing type lateral UKA.
Level of evidence
KeywordsLateral unicompartmental knee arthroplasty Bearing design Annual revision rate Lateral UKA
Unicompartmental knee arthroplasty
Range of motion
Patient-reported outcome measures
Body mass index
Total knee arthroplasty
Methodological index for non-randomized studies
Knee Society Score
Oxford Knee Scores
We would like to thank Willy Salemink from the Spaarne Gasthuis library for her assistance in the literature search.
JB performed the literature search, scanned all abstracts and full texts of the included articles, determined the quality of the studies and wrote the manuscript. LK screened all abstracts, full texts and determined the quality of the studies as a second author; and helped to draft the manuscript. IS provided suggestions on the review process, statistical analyses and manuscript; and checked the data extraction. HG participated in the design of the study and revised the manuscript. PN coordinated this study, participated in its design and revised the manuscript. All authors read and approved the final manuscript.
No funding has been received for this study.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interests.
No ethical approval was obtained because this study was a systematic review using de-identified data from other cohort studies.
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