Treatment of Large Cartilage Defects in the Knee by Hydrogel-Based Autologous Chondrocyte Implantation: A 5-Year Follow-Up of a Prospective, Multicenter, Single-Arm Phase III Trial

ObjectiveTo evaluate efficacy and safety at 5 years after treatment with hydrogel-based autologous chondrocyte implantation (ACI) for large cartilage defects in the knee.DesignProspective, multicenter, single-arm, Phase III clinical trial. ACI was performed in 100 patients with focal full-thickness cartilage defects ranging from 4 to 12 cm² in size. The primary outcome measure was the responder rate (defined as improvement by ≥10 points) at 2 years using the Knee Injury and Osteoarthritis Outcome Score (KOOS).ResultsThe preoperative overall KOOS was 39.8 points and continuously increased to 84.7 points at 5 years (mean increase 44.1 points, 95% CI = 40.4-47.9, <i>P</i> < 0.0001). The primary study endpoint (i.e., a KOOS responder rate of >40%) was descriptively met at each assessment timepoint from 3 months to 5 years (Month 3: 75.5%, 95% CI = 65.6-83.8; Year 2: 93.0%, 95% CI = 86.1-97.1, Year 5: 92.8%, 95% CI = 85.7-97.0). International Knee Documentation Committee (IKDC) subjective and objective scores and quality of life assessments (EQ-5D-5L) supported the results seen for the KOOS. The overall treatment failure rate at 5 years was 1%. All treatment-related adverse events were of mild or moderate intensity and mostly occurred within the first year after treatment.ConclusionsHydrogel-based ACI has been shown to be a safe and effective treatment option for patients with large knee cartilage defects with sustained efficacy up to 5 years as demonstrated by consistent and clinically relevant improvements in all investigated efficacy variables. No remarkable adverse events or safety issues were noted.