Metal-Backed Tibial Components Offer Comparable Patient-Reported Outcome Measures With Lower Revision Rates Compared With All-Polyethylene Tibial Components in Medial Fixed-Bearing Unicompartmental Knee Arthroplasty: A Systematic Review and Meta-Analysis.

Background: Two tibial component designs are mainly used in fixed-bearing unicompartmental knee arthroplasty (UKA): metal-backed (MtB) and all-polyethylene (AP). While AP components allow for increased polyethylene thickness with minimal bone resection, MtB implants offer modularity for isolated bearing exchange and potentially superior stress distribution. However, controversy remains regarding their respective revision rates and patient-reported outcome measures (PROMs).

Methods: We conducted a systematic review and meta-analysis following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered our protocol on International Prospective Register of Systematic Reviews (CRD42024604110). A comprehensive search was performed in PubMed, Web of Science, Embase, and Scopus up to December 10, 2024, without language restrictions. Studies comparing MtB and AP tibial components in medial fixed-bearing UKA were included, assessing revision rates, PROMs, and range of motion (ROM). Data were extracted independently by 2 reviewers, and statistical analysis was performed using a random-effect model. Odds ratios (ORs) were calculated for all-cause revision and aseptic tibial loosening rates, whereas mean differences were calculated for PROMs and ROM.

Results: Sixteen studies involving 34,738 participants (34,998 knees) were included, with 21,097 knees receiving MtB prostheses and 13,836 receiving AP prostheses. The overall all-cause revision and aseptic tibial loosening rates were significantly lower in the MtB group: OR, 0.49; 95% confidence interval (CI), 0.31-0.79; p = 0.003 and OR, 0.29; 95% CI, 0.09-0.99; p = 0.048, respectively. However, PROMs-including Knee Society Score, Knee Society Function Score, Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score, Short Form-36, and ROM-were comparable between groups.

Conclusion: MtB tibial components in medial fixed-bearing UKA offer comparable PROMs and ROM with significantly lower rates of both all-cause revision and revision because of aseptic tibial component loosening relative to AP designs.

Level of evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.