Experimental Study of 3D Printing Technique Combined with Biphasic Calcium Phosphates in the Treatment of Canine Model of Osteonecrosis of the Femoral Head

Objective: This study attempts to use a digital design of 3D printing technology to create a surgical navigation template. At the same time, biphasic calcium phosphates (BCP) were used in the treatment of animal models of osteonecrosis of the femoral head (ONFH) basis on accurate positioning of necrotic lesions in the navigation templates and observing its therapeutic effect. Methods: : 15 healthy adult beagle dogs of male and female, weight (20 + 2) kg, after establishing the model of ONFH using liquid nitrogen freezing method, were randomly divided into 3 groups (n=5). Each model underwent necrosis lesions and BPC implantations in one side of femoral head, and only underwent necrosis lesions in one other side of femoral head. Each group underwent CT examination, gross observation,histological examination and immunohistochemical staining at 6 weeks, 12 weeks and 18 weeks postoperatively. Results: : At weeks 6, 12, and 18, CT and gross examination showed that the necrotic area in the experimental group was basically intact and had been completely raised by BCP material. In the control group, there were signs of bone repair in the femoral head, but there were still large bone defects and cavities,At week 18, extensive collapse of the cartilage surface was observed.Through histological examination, in the experimental group at 12 and 18 weeks, a large number of new and reconstructed bone trabeculae containing a large amount of collagen fibers were observed (P<0.05), while in the control group, there was extensive necrosis of the bone trabeculae without cellular structural areas.Immunohistochemical examination observation: A large number of CD31 positive cells were observed in the experimental group at 6 weeks, gradually decreasing at 12 and 18 weeks (P<0.05), while a small number of CD31 positive cells were observed in the control group at 18 weeks. Conclusion: 3D printing navigation template can accurately locate the ONFH lesions. Implantation of BCP material can effectively play a supporting role, prevent the collapse of the loading surface, and induce bone formation and angiogenesis to some extent.