May the 4th be with you: mixed-methods best-evidence synthesis on 4th-generation alumina-zirconia ceramic bearings in total hip arthroplasty.

Purpose: To assess utility, benefits, and risks of 4th-generation alumina-zirconia ceramic pairings in elective total hip arthroplasty (THA).

Methods: A comprehensive mixed-methods best-evidence synthesis using data from systematic reviews, randomized controlled trials (RCTs), prospective and retrospective cohort studies, as well as joint replacement registries, was conducted to estimate overall revision and survival rates, periprosthetic infection, bearing fractures, and noise phenomena with 4th-generation alumina-zirconia ceramic versus other tribological couplings in elective THA. The systematic review part across multiple databases was registered with PROSPERO (CRD42023418076), and individual study data were extracted for statistical re-analysis.

Results: Twenty overlapping systematic reviews, 7, 17, and 8 references from RCTs, cohort studies, and joint replacement registries form the basis of this work. According to current best evidence, it is (i) 15-33 times more likely that 4th-generation alumina-zirconia pairings avoid a revision for infection than causing a revision for audible noise, (ii) 38-85 times more likely that 4th-generation alumina-zirconia pairings avoid a revision for infection than causing a revision for ceramic head fractures, and (iii) three to six times more likely that 4th-generation alumina-zirconia pairings avoid a revision for infection than cause a revision for ceramic liner fractures.

Conclusion: Fourth-generation alumina-zirconia pairings in THA show a favorable benefit-risk ratio, with rare compound-specific adverse events and complications significantly outbalanced by long-term advantages, such as a markedly lower incidence of revision for infection.