The post-operative loading regimen influences the regenerative potential of a biomimetic osteochondral scaffold.

BACKGROUND: Articular cartilage (AC) is highly resilient and deformable. Osteochondral scaffolds have been developed to repair cartilage by mimicking the structure and function of native tissues. Our experimental model was conducted on adult sheep, commonly used as an animal model for cartilage studies, to assess the effect of early loading after osteochondral implant placement. METHODS: The study was conducted on 16 adult male sheep. Cartilage defects were created and filled with an osteochondral scaffold. The sheep were divided into three groups: Group A (immobilization), Group B (partial load), and Group C (full load). Weekly clinical exams were performed, followed by micro-computed tomography (micro-CT) and atomic force microscopy (AFM) analysis on the knees, which were later collected after 6 months. The results assessed the effectiveness of partial loading compared to full immobilization or full load in terms of scaffold integration. RESULTS: After 6 months, sheep in Group B moved without limping, whereas Groups A and C showed limited movement of the operated limb. In Group B, micro-CT analysis showed different scaffold integration and adequate osteochondral defect filling, while fibrocartilage tissue was observed in Groups A and C. Group A exhibited increased subchondral bone porosity. Group C showed increased osteochondral mineralization. AFM measurements revealed a rough surface with fiber-like structures in the cartilage area compared to the subchondral bone. DISCUSSION: After 6 months, Group B showed better mobility recovery compared to the other groups. Micro-CT analysis revealed different scaffold integration and defect filling in Group B, while fibrocartilaginous tissue was found in Groups A and C. This study highlights the importance of controlled mechanical loading in osteochondral scaffold healing and integration. CONCLUSION: Our study highlighted the importance of controlled mechanical loading in osteochondral scaffold development for cartilage repair. Partial load proved favorable for scaffold healing and integration, improving mobility and reducing limping in the animal model.