ObjectiveTo investigate the ability to repair osteochondral defect and the biocompatibility of porous tantalum loaded with bone morphogenetic protein 7 (BMP-7) by observing the effect of porous tantalum loaded with BMP-7 in repairing articular cartilage and subchondral bone defect. MethodsThe cartilage defect models of medial femoral condyle were established in 48 New Zealand white rabbits, which were randomly divided into 3 groups (n=16): porous tantalum material+BMP-7 (group A) and porous tantalum material (group B) were implanted into the right side of the medial femoral condyle; and no material was implanted as control (group C). The general condition of animals was observed after operation, then the specimens were harvested for gross observation, histological observation, and scanning electron microscope (SEM) observation at 4, 8, and 16 weeks after implantation, micro-CT was used to observe the cartilage and bone ingrowth and bone formation around porous tantalum at 16 weeks after implantation. ResultsNo animal died after operation and wound healed well. Gross observation showed that defects of groups A and B were covered with new cartilage with time, but earlier new cartilage formation and better repair were observed in group A than group B, no repair occurred at the site of bone defects, and defect surface was filled with fibrous tissue in group C. Cartilage repair gross score of group A was significantly higher than that of group B at 8 and 16 weeks (P < 0.05) but no significant difference was found between groups A and B at 4 weeks (P>0.05). SEM observation showed that the number of new cartilage and osteoblasts increased gradually with time, and the implanted material was gradually covered with the extracellular matrix, and the new bone tissue grew into the pores of the material; the neonatal bone tissue and extracellular matrix secretion of group A were significantly more than those of group B. The toluidine blue staining results showed that new cartilage and bone tissue gradually increased in the porous tantalum interface, and new bone trabecula formed and grew in the pores, the bone and the porous tantalum contact tended to close, and cartilage defect was gradually covered with cartilage like tissue, cartilage tissue and porous tantalum combined more closely in groups A and B at 4, 8 and 16 weeks. New cartilage and bone tissue of group A was more than that of group B. Micro-CT analysis indicated that the bone mineral density, trabecular thickness, trabecular number, and bone volume fraction of group A were significantly higher than those of group B at 16 weeks (P < 0.05), but the trabecular bone space was significantly lower than that of group B (P < 0.05). ConclusionThe domestic porous tantalum has good biocompatibility, domestic porous tantalum loaded with BMP-7 can promote the formation of a stable connection with the host and has a good effect on cartilage and subchondral bone defect repair.