Costal Chondrocyte–Derived Pellet-Type Autologous Chondrocyte Implantation versus Microfracture for Repair of Articular Cartilage Defects: A Prospective Randomized Trial

Objective: To compare the efficacy and safety of costal chondrocyte–derived pellet-type autologous chondrocyte implantation (CCP-ACI) with microfracture (MFx) for repair of articular cartilage defects of the knee. Design: Thirty subjects with an International Cartilage Repair Society (ICRS) grade 3 to 4 chondral defect (2-10 cm² in area; ≤4 cm³ in volume) were randomized at a ratio of 2:1 (CCP-ACI:MFx). Twenty patients were allocated in the CCP-ACI group and 10 patients in the MFx group. CCP-ACI was performed by harvesting costal cartilage at least 4 weeks before surgery. Implantation was performed without any marrow stimulation. Efficacy and safety were assessed at weeks 8, 24, and 48 after surgery according to the magnetic resonance observation of cartilage repair tissue (MOCART) score and clinical outcomes. Results: MOCART scores improved from baseline to 24 and 48 weeks postoperatively in both treatment groups. The improvement in MOCART scores in the CCP-ACI group was significantly greater than that in the MFx group at 24 and 48 weeks (39.1 vs 21.8 and 43.0 vs 24.8, respectively). The proportions of complete defect repair and complete integration were significantly higher in the CCP-ACI group than the MFx group at 48 weeks. Improvement in Lysholm score and KOOS subscores, including Function (Sports and Recreational Activity) and knee-related quality of life was significantly greater in the CCP-ACI group than the MFx group at 48 weeks (35.4 vs 31.5, 35.7 vs 28.5, and 27.9 vs 11.6, respectively). Conclusion: Treatment of cartilage defects with CCP-ACI yielded satisfactory cartilage tissue repair outcomes, with good structural integration with native cartilage tissue shown by magnetic resonance imaging at 24 and 48 weeks after surgery. Level of Evidence: Level 1: Randomized controlled study.