Unicompartmental versus total knee arthroplasty for knee osteoarthritis

Purpose: In the last couple of years, a significant amount of studies comparing the UKA and TKA for unicompartmental knee osteoarthritis have been published. However, there is a lack of recent meta-analysis comparing the two implants. Since the number of performed UKAs is currently increasing and the indications are obsolete, it becomes important to update current evidences and outcomes. With these premises, a meta-analysis of clinical trials comparing UKA versus TKA was conducted.

Methods: In October 2018, the following databases were accessed: Cochrane Systematic Reviews, Scopus, PubMed and Google Scholar. According to the Oxford Center of Evidence-based Medicine, level of evidence articles I to III were included. Only studies reporting quantitative data concerning the outcomes of interest were included. For the statistical analysis and the methodological quality assessment, we referred to the Review Manager Software 5.3. Dichotomous data were analyzed through the Mantel-Haenszel statistical method with the odd ratio effect measure. For continuous data, the inverse variance statistical method was used with the mean difference effect measure. A confidence interval of 95% was considered for analysis. To evaluate study heterogeneity, both Chi-square and Higgins tests were performed. Values of P < 0.05 were considered statistically significant.

Results: The overall methodological quality assessment was moderate. The risk of publication's bias was moderate. We enrolled in this study a total of 13,789 patients. The mean follow-up was 42.69 months. The UKA evidenced increased risk of revision's surgeries (OR 2.16, P > 0.0001). All the other scores of interest were in favor of the UKA: Oxford Knee Score, KSS Clinical, WOMAC overall and related subscales. The UKA also reported better functional outcomes: KSS Function, longer walking distance, improvement of the joint flexion and ROM. Moreover, in the UKA group have been reported a shorter length of stay, reduced estimated total blood loss and shorter surgical duration.

Conclusion: The main findings of this meta-analysis are that UKA reported a reduced survivorship but better clinical and functional performances compared to TKA. Furthermore, shorter surgical duration, lower total estimated blood loss and quicker hospitalization length were observed in the UKA cohort.