Clinical Effectiveness and Magnetic Resonance Imaging-Based Endurability of Matrix-Associated Autologous Chondrocyte Implantation with an Autologous Periosteal Flap for Articular Cartilage Defects of the Knee Joint

Objectives: To evaluate the effectiveness and durability of matrix-associated autologous chondrocyte implantation with periosteal flap (pMACI) in treating knee cartilage defects using clinical scores and MRI evaluations. Methods: Data were collected from 37 knees of 17 patients, with a mean follow-up of 5 years (range: 0.1–20 years). Clinical outcomes were assessed using the Lysholm Knee Scoring Scale (LKS) and Knee Injury and Osteoarthritis Outcome Score (KOOS). Tissue quality was quantitatively evaluated using MRI T1ρ and T2 mapping (biochemical) and MR observation of cartilage repair tissue: MOCART 2.0 (morphological). A linear mixed model was used to identify factors affecting outcomes, including etiology (trauma, OCD, OA), graft site, and defect size. Results: At the 20-year follow-up, clinical scores remained significantly improved from baseline (mean LKS: 55.6 to 86.5; KOOS: 37.8 to 70.8). The biochemical MRI parameters (T1ρ and T2 values) stabilized at levels comparable to native cartilage across all etiologies and sites (p = 0.326 and 0.412, respectively), indicating stable long-term tissue quality. In contrast, the MOCART 2.0 scores significantly declined over time (annual rate: −1.14 points; p < 0.001). Etiology was a significant factor; the OA group showed significantly lower clinical and MOCART scores compared to the trauma/OCD groups (p < 0.05). However, no significant differences were found in LKS and KOOS based on graft site (p = 0.489) or defect size (p > 0.05). Conclusions: pMACI may be a highly durable treatment capable of maintaining biological tissue quality and providing clinical benefits for two decades. The observed morphological deterioration after 20 years likely reflects joint-wide aging—especially in OA cases—rather than graft failure, highlighting the importance of long-term MRI monitoring.