A Hyaluronate-Atelocollagen/β-Tricalcium Phosphate-Hydroxyapatite Biphasic Scaffold for the Repair of Osteochondral Defects: A Porcine Study

The authors had devised a novel biphasic scaffold combining hyaluronic acid and atelocallagen for the chondral phase and combining hydroxyapatite and β-tricalcium phosphate for the osseous phase. Sixty-four osteochondral defects were created in the knee joints of 16 minipigs to evaluate the effectiveness of this scaffold for repairing cartilage in a large animal model. The defects were divided into five groups according to their treatment: filling with a cell/biphasic scaffold composite (Group I, 16 defects); implanting only the biphasic scaffold (Group II, 16 defects); placing the removed osteochondral fragments back into the defect (Group IIIa, 8 defects); autologous chondrocyte implantation (Group IIIb, 8 defects); leaving the defects empty (Group IV, the negative control). After 5 months, the International Cartilage Repair Society Macroscopic Score was similar in Group I (9.0), Group II (9.1), and Group IIIa (9.1), followed by Group IIIb (7.4) and Group IV (6.2). Except for three defects noted in Group IV, all the defects were filled with cartilaginous or fibrous tissue depending on the groups. The junction to the adjacent native cartilage was detectable in all the groups of minipigs. Microscopically, Group II had the highest score from the International Cartilage Repair Society Visual Histological Assessment Scale. The indentation study showed that the maximum loads and time constant of Group I, II, and IIIa defects were comparable to that of native cartilage, whereas the equilibrium loads of these groups were slightly greater than that of native cartilage. In conclusion, our results suggest that a biphasic osteochondral scaffold with a chondral phase, consisting of hyaluronate and atelocollagen, and an osseous phase, consisting of hydroxyapatite and β-tricalcium phosphate, is effective for repairing osteochondral defects in a large animal model.