Clinical Outcomes of Biomaterial-Based Cartilage Repair Strategies for Knee Chondral Defects: A Systematic Review and Meta- Analysis

Abstract Background Articular cartilage is a smooth, water-based cartilage that lines bone surfaces in synovial joints such as the knee and hip, providing a frictionless surface for movement and absorbing biomechanical shock. Defects of this tissue are a common cause of pain and functional impairment, yet repair of these defects remains challenging because of the poor regenerative capacity of cartilage. Hydrogel-based scaffolds are increasingly used to augment cartilage repair by supporting tissue regeneration. However, reported MRI and clinical outcomes remain heterogeneous. This systematic review and meta-analysis evaluated MRI-based and patient-reported outcomes following hydrogel-assisted cartilage repair for focal knee articular cartilage defects. Methods This systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered with the International Prospective Register of Systematic Reviews (PROSPERO). PubMed/MEDLINE, Embase, Scopus, and Cochrane CENTRAL were searched for eligible studies evaluating hydrogel-based cartilage repair in adults with focal knee cartilage defects. The primary outcome was the 12-month MOCART score. The secondary outcome was International Knee Documentation Committee (IKDC) score. Risk of bias was assessed using the Methodological Index for Non-Randomized Studies (MINORS) instrument. Results Seven studies, including 160 reported cartilage repair outcomes, met inclusion criteria. Pooled random-effects meta-analysis revealed a mean MOCART score of 71.2 (95% CI 66.2–76.2) and mean IKDC score of 70.2 (95% CI 65.5–74.9). CarGel subgroup analysis produced a pooled MOCART score of 68.9 (95% CI 65.3–72.5) and negligible heterogeneity (I² = 0%). Leave-one-out analysis showed no substantial alteration of pooled estimates. Conclusion Hydrogel-based articular cartilage repair was associated with encouraging MRI based and patient-reported function, supporting the role of hydrogel scaffolds as adjuncts to marrow stimulation by helping promote reproducible early repair tissue formation. Future comparative studies should standardize imaging and clinical outcome reporting, incorporate longer term follow-up, and directly compare hydrogel biomaterial categories.