Abstract
BACKGROUND: Meniscal injuries, involving damage to the critical fibrocartilaginous structure of the knee joint, often necessitate surgical intervention, including meniscal allograft transplantation or the use of commercial implants. Despite advances in implant based therapies, there is no consensus regarding the comparative efficacy of collagen meniscus implants (CMI) versus polyurethane-based (PU-based) scaffolds. This review aimed to systematically evaluate and compare the clinical outcomes associated with these two implant types for partial meniscal repair. METHODS: A comprehensive systematic review was conducted to evaluate the clinical outcomes of meniscal implants by searching multiple databases including Medline/PubMed, Web of Science, Embase, Scopus, and Cochrane in the temporal range of 1999-2024. The review focused on pre-post studies and assessed various patient-reported outcome measures, including the visual analog scale (VAS), international Knee Documentation Committee (IKDC), Lysholm, knee injury and osteoarthritis outcome score (KOOS), as well as the Tegner activity score. These outcomes were evaluated across different follow-up periods [short-term (6 month to 2.5 years), mid-term (2.5-5 years) and long-term (10 years)] following meniscal implant implantation. A random-effects meta-analysis model was used to address heterogeneity, along with a sensitivity analysis to evaluate the robustness of pooled estimates. The National Institutes of Health (NIH) quality assessment tool was utilized to assess the methodological quality in the studies. RESULTS: The meta-analysis identified 26 studies that met the inclusion criteria, and the overall quality of the included studies was mostly fair to good. The analysis showed that both CMI and PU-based scaffolds improved clinical outcomes in patients with partial meniscus injuries, with the implants evaluated across short-term, mid-term, and long-term follow-up periods. Specifically, the analysis found: the VAS scores significantly improved during the short-term follow-up by an average of -1.86 points for CMI and -1.98 points for PU-based scaffolds. Lysholm scores significantly improved at short-term follow-up, increasing by an average of 29.26 points for CMI and 24.98 points for PU-based scaffolds. For the Tegner score, CMI implants showed an average increase of 2.02 points in the short-term, while PU-based implants exhibited a negligible change of -0.05 points. CONCLUSIONS: Both CMI and PU-based scaffolds demonstrated improved clinical outcomes, but showed some differences in effectiveness over follow-up periods. PU-based scaffolds offer faster integration and short-term effectiveness, while CMI promotes gradual tissue regeneration and long-term stability. Although these differing characteristics support personalized meniscal repair strategies, the lack of comparative studies limits definitive clinical guidance. LEVEL OF EVIDENCE: Level III, IV.