Osteochondral regeneration with a tri-layered biomimetic resorbable scaffold: In vivo study in a sheep model up to 12 months of follow-up

The treatment of osteochondral joint lesions requires the regeneration of both articular cartilage and subchondral bone tissue. Scaffold-based strategies aimed at mimicking the native osteochondral structure have been explored with mixed results. The aim of this study was to evaluate the regenerative potential of a tri-layered osteochondral cell-free scaffold in a large animal model at both 6 and 12 months of follow-up. Bilateral critical-sized osteochondral defects were created in 22 sheep. One defect was filled with the scaffold, whereas the contralateral was left empty. The repair tissue quality was evaluated at 6 and 12 months of follow-up in terms of macroscopic appearance, histology, trabecular bone formation, and inflammation grade. The mean global ICRS II score in the scaffold and control groups was 41 ± 11 vs 30 ± 6 at 6 months (p = 0.004) and 54 ± 13 vs 37 ± 11 at 12 months (p = 0.002), respectively. A higher percentage of bone was found in the treatment group compared to controls both at 6 (BV/TV 48.8 ± 8.6 % vs 37.4 ± 9.5 %, respectively; p < 0.001) and 12 months (BV/TV 51.8 ± 8.8 % vs 42.1 ± 12.6 %, respectively; p = 0.023). No significant levels of inflammation were seen. These results demonstrated the scaffold safety and potential to regenerate both cartilage and subchondral tissues in a large animal model of knee osteochondral lesions.