Objectives: Cartilage defect of the knee joint is a common cause of knee pain and can result in significant functional disability due to its limited capability of spontaneous healing. Existing surgical options—such as microfracture, cartilage or chondrocyte transplantation, and joint replacement—remain limited by inconsistent restoration of durable hyaline cartilage. Autologous collagen-induced chondrogenesis (ACIC), which employs a collagen scaffold, has emerged as a promising single-stage alternative. Nevertheless, high-quality evidence evaluating its long-term efficacy relative to microfracture alone is still lacking. This study investigates the clinical effect of arthroscopic microfracture combined with autologous collagen-induced chondrogenesis for knee cartilage defects over a 5-year follow-up.
Methods: Twenty patients with knee cartilage defects were randomized to receive ACIC + microfracture (n = 10) or microfracture alone (MF, n = 10). Outcomes were assessed using Lysholm, VAS, and IKDC scores at baseline, 1 week, 3, 6, 12 months, and 5 years, alongside MRI-based MOCART scoring. Analyses employed linear mixed-effects models with multiplicity correction and effect size reporting.
Results: Both groups showed significant within-group improvements in Lysholm, VAS, and IKDC over time, but there were no between-group differences and no significant Group × Time interactions, indicating comparable functional recovery. In contrast, the MOCART score showed a significant long-term Group × Time interaction at 5 years (β = 53.1, 95% CI 29.0–77.2, p < 0.001), favoring ACIC + MF. At 5 years, ACIC + MF demonstrated a large structural advantage, although the unadjusted Mann–Whitney p = 0.0196 did not remain significant after multiplicity correction (adjusted p = 0.098).
Conclusion: ACIC + MF resulted in superior long-term structural repair compared with MF, as reflected in MOCART scores, but this did not translate into superior patient-reported outcomes. These findings underscore the divergence between imaging-based repair and clinical function and highlight the need for prospective trials establishing anchor-based MCID and Patient Acceptable Symptom State (PASS) thresholds for MOCART to clarify its clinical significance.
Trial Registration: Chinese National Medical Research Registration and Archival Information System: ChiCTR2400080094
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2026 The Author(s). Orthopaedic Surgery published by Tianjin Hospital and John Wiley & Sons Australia, Ltd.
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