Cruciate-Retaining Implants Do Not Provide a More Natural Joint Feeling Than Cruciate-Substituting Implants in Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

BACKGROUND

The Forgotten Joint Score (FJS) is a patient-reported outcome measure developed to assess joint awareness, potentially differentiating between "good" and "excellent" outcomes. Prosthetic designs, specifically cruciate-retaining (CR) and cruciate-substituting (cruciate sacrificing/substituting [CS]) implants, may influence joint awareness due to differences in posterior cruciate ligament (PCL) preservation. Our objective was to compare the joint awareness outcomes, measured by the FJS, between CR and CS implants in total knee arthroplasty (TKA).

METHODS

A systematic review and meta-analysis were conducted following PRISMA guidelines. Scopus, PubMed, Embase, and Web of Science were searched up to March 2024 without date or language restrictions. Studies comparing CR and CS implants reporting FJS outcomes were included. Data extracted included study characteristics, patient demographics, intervention details, follow-up durations, and FJS scores. Risk of bias was assessed using the Risk of Bias in Nonrandomized Studies of Intervention-I tool. A random-effects meta-analysis using Hedges g was performed, with sensitivity analyses and meta-regression to explore heterogeneity.

RESULTS

Seventeen cohort studies involving 4,245 patients were included. The meta-analysis demonstrated that CS implants were superior to CR implants in terms of FJS (Hedges g = -0.39; p = 0.018), indicating a small to medium effect size favoring CS designs. High heterogeneity was observed (I = 95.69%). Sensitivity analyses yielded similar results, and meta-regression did not identify significant sources of heterogeneity.

CONCLUSION

CS implants are associated with superior joint awareness compared with CR implants in TKA, as measured by the FJS. Despite the theoretical advantage of PCL preservation, CR implants did not demonstrate better joint awareness. The findings should be interpreted with caution due to study heterogeneity and limitations in study design. Further high-quality randomized controlled trials are necessary to confirm these results.