Effects of combined hydroxyapatite and human platelet rich plasma on bone healing in rabbit model: radiological, macroscopical, hidtopathological and biomechanical evaluation

Hydroxyapatite is an osteoconductive material used as a bone graft extender and exhibits excellent biocompatibility with soft tissues such as skin, muscle and gums, making it an ideal candidate for orthopedic and dental implants or components of implants. Synthetic hydroxyapatite has been widely used in repair of hard tissues, and common uses include bone repair, bone augmentation, as well as coating of implants or acting as fillers in bone or teeth. On the other hand, human platelet rich plasma (hPRP) has been used as a source of osteoinductive factor. A combination of hPRP and hydroxyapatite is expected to create a composite with both osteoconductive and osteoinductive properties. This study examined the effect of a combination of hydroxyapatite and hPRP on osteogenesis in vivo, using rabbit model bone healing. A critical size defect of 10 mm long was created in the radial diaphysis of 36 rabbit and either supplied with hydroxyapatite-human PRP or hydroxyapatite or was left empty (control group). Radiographs of each forelimb were taken postoperatively on 1st day and then at the 2nd, 4th, 6th and 8th weeks post injury to evaluate bone formation, union and remodeling of the defect. The operated radiuses of half of the animals in each group were removed on 56th postoperative day and were grossly and histopathologically evaluated. In addition, biomechanical test was conducted on the operated and normal forearms of the other half of the animals of each group. This study demonstrated that hydroxyapatite-humanPRP, could promote bone regeneration in critical size defects with a high regenerative capacity. The results of the present study demonstrated that hydroxyapatite-hPRP could be an attractive alternative for reconstruction of the major diaphyseal defects of the long bones in animal models.