Is Cell-Free Collagen Matrix Effective in the Treatment of Large Cartilage Defects of Knee? Early Functional and Quantitative Magnetic Resonance Imaging Cartigram Assessment in Two Patients.

INTRODUCTION: Articular cartilage injuries, particularly large full-thickness defects (International Cartilage Repair Society Grade IV), present a significant challenge due to the tissue's limited regenerative capacity. Cell-free collagen matrix, an acellular Type I collagen matrix, has shown promise in promoting cartilage repair. However, its role in treating large chondral defects of the knee with objective radiological correlation remains underexplored. Through two case reports, we have shown that cell free collagen matrix is also effective in early healing of large cartilage defects of knee. To the best of our knowledge, this is among the first reports to document healing of large chondral defects using cell free collagen matrix assessed by quantitative T2 mapping.

CASE REPORT: We have presented two cases of large, isolated chondral defects of the medial femoral condyle treated with acellular collagen matrix. Both patients, one 17-year-old male and another 33-year-old male with large chondral defects (3.5 × 2.5 cm and 4 × 2 cm) of knee underwent diagnostic arthroscopy and loose body removal followed by cartilage repair using acellular collagen matrix through mini-open arthrotomy. Functional outcomes were evaluated using International Knee Documentation Committee (IKDC) and Lysholm scores. Cartilage healing was assessed at 6 months with quantitative magnetic resonance imaging using T2 mapping (Cartigram). Both patients demonstrated marked early functional improvement, with IKDC scores increasing from 31.03 to 71.26 in first case and 33.33-73.56 in second case, while Lysholm scores increased from 38 and 42 to 85 in both the patients at 6 months. Cartigram revealed T2 relaxation times at the repair sites are comparable to the adjacent normal cartilage, suggesting excellent hyaline-like cartilage regeneration.

CONCLUSION: Cell free collagen matrix is effective in early healing of isolated large Grade IV cartilage defects of knee, by promoting hyaline like cartilage regeneration with excellent radiological and functional outcomes. Further studies with large population size and longer follow-up are needed to be done to establish its long-term efficacy.