水酸化アパタイト・多孔質立方体のビーグル犬広範骨欠損部単独充填の検討

Abstract

Porous cuboidal hydroxyapatite (HAp) as a substitute of cancelous bone is a bioactive ceramics, and its tissue affinity as well as osteo-conductivity have been proven experimentally by Niwa et al. However, to fill the large cancellous bone defects by HAp alone, it is not clearly understood if HAp should be implanted with autogenous bone. So, the large bone defects created by curettage of cancellous bone in distal femur and proximal tibia in seven beagle dogs were filled by 4.3mm3 HAp 5 to 10 pieces. After the implantation of HAp, radiological observation by Fuji computed radiogram and histological evaluation by H-E stain and Villanueva non-decalcified stain were carried out from the bone specimens resected serially 2 to 44 weeks. Radiologically by 4 to 8 weeks after HAp implantation, the space between HAp and the preexisting bone which was mainly cortex, was reduced by radiodense newly formed trabeculae except the open window in femur site. Histologically in 2 weeks, new trabecular bone formation with abundant vascularization was observed between HAp and the preexisting bone. By 4 to 12 weeks, fibrous tissue in HAp was gradually transformed to immature bone adherent to HAp, and fibrous tissue was replaced by normal bone marrow. In 44 weeks, the porous cavities seemed enlarged by the resorption of HAp. So, the solo implantatiom of HAp in large bone defects is probably safe and secure procedure because new bone formation in and around HAp is conducted early to enforce the fragility of HAp without foreign body reactions.