Biomechanical properties of cartilage repair tissue after different cartilage repair procedures in sheep

Aim: The purpose of this study was to evaluate the biomechanical quality of cartilage and repair tissue in a sheep's knee. 4 standardized 7 mm defects were created on the media] femoral condyle and on the patellar groove (n = 22). These were treated with 4 different cartilage repair procedures and examined I year later. Material and Methods: The different groups were: (1) a cell-seeded collagen type-1/111-membrane (Chondro Gide(R)) glued into the defect; (2) a collagen type-1/111-membrane, sutured and cells injected underneath; (3) an engineered, cell-seeded collagen type-II-membrane, glued; (4) periosteum sutured and cells injected underneath; (5) Controls: healthy contra-lateral knees. Indentation tests were performed to reveal the biomechanical capacity. From creep indentation over 35 s a,,25-s creep index was calculated. A high creep index means that the cartilage can undergo greater and faster compression. Results: The repair tissue was significantly thinner than the normal cartilage. The mean creep index of all repair tissues was measured at 111 and 125, respectively (p < 0.05). There were no significant differences among the treated groups. Conclusion: In this animal study, none of the induced repair tissues was biomechanically comparable to genuine articular cartilage.