Rapid Establishment and Validation of an Experimental Model of Osteoporosis for Implant-Bone Analysis

Osteoporosis is an increasingly prevalent disease. The development of an osteoporosis-like experimental animal model is of great importance for the study of peri-implant osteogenesis in osteoporosis. The present authors aimed to establish a rapid modeling method of osteoporotic rabbits for implant-bone analysis and validate whether the models can affect the implant osseointegration. The present study included 29 female New Zealand rabbits (age: 5 to 6 months). Two rabbits were lost during anesthetization. Of the remaining 27 rabbits, 18 received an ovariectomy, with 9 receiving dexamethasone injections for 8 weeks (OVX+D group) and 9 receiving equivalent-volume saline injections (OVX group). As a control group, the remaining 9 rabbits were sham-operated and received an equivalent volume of normal saline (SHAM group). Then, serum biochemical markers of bone metabolism were detected and densitometric measurements were performed. Implants were then placed in the tibias of each rabbit. Bone samples (including implants) were obtained after 4, 8, and 12 weeks of healing and were subjected to histologic and histomorphometric analyses. The results showed that the OVX+D group experienced a 32% reduction in bone mineral density (BMD) from baseline. The BMD of the OVX+D group was significantly lower than that of the SHAM and OVX groups. Moreover, alkaline phosphatase (ALP) blood concentrations of in the OVX+D group were increased significantly. The osteoporotic rabbits exhibited marked decreases in osseointegration, characterized by slowed bone formation and decreased bone-to-implant contact (BIC). The combination of an ovariectomy and dexamethasone injections could experimentally induce osteoporosis in rabbits in the short term, which can be used as an appropriate animal model to study the osseointegration of implants under osteoporosis.