All-Polyethylene Versus Metal-Backed Tibial Components in Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials

Background In the literature, there is no evidence suggesting the superiority in clinical performance between all-polyethylene (AP) and metal-backed (MB) tibial implants in total knee arthroplasty (TKA). The aim of this study was to systematically review the literature to collect only high-quality studies investigating the differences in terms of clinical and radiostereometric analysis (RSA) outcomes of AP compared to MB implants. Methods Only randomized controlled trials (RCT) reporting either clinical or RSA outcomes have been included. Data sources were Embase, Medline, and the Cochrane Central Register of Controlled Trials. Results We included eleven RCTs evaluating the outcomes of 1,377 patients. Of the RCTs, nine of them showed a low risk and two showed moderate risk of bias. There was no statistically significant difference in terms of clinical outcomes and survival rate between the AP and MB group, however, a statistically significant lower mean lift-off in the AP group (0.19 mm) compared to the MB group (0.3 mm) was observed on RSA. Conclusions The performance of AP TKA in terms of clinical outcomes and 5-year survival was not statistically different when compared to the MB group. However, the RSA showed a statistically significant lower mean lift-off in the AP group.