title: Resorption of synthetic porous hydroxyapatite and replacement by newly formed bone.
abstract: Synthetic porous hydroxyapatite (HA) is commonly used as a bone substitute for bone defects which, previously, would have been treated by autogenous bone grafting. HA has been thought to be a nonbiodegradable material that remains as it is implanted. However, after long-term follow-up, some authors report that the margin of implanted HA blocks or granules is absorbed, suggesting that HA is biodegradable. We experienced a patient in whom synthetic HA blocks implanted in a bone defect of the ilium after the harvesting of full-thickness bone for grafting were extensively absorbed and replaced by newly formed bone 6 years and 7 months after the implantation. Therefore, we conclude that HA is biodegradable. Sintering temperature, porosity, and pore diameter seem to influence the biodegradability of HA.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Goto
authors.forename: T
authors.initials: T
authors.lastname: Kojima
authors.forename: T
authors.initials: T
authors.lastname: Iijima
authors.forename: S
authors.initials: S
authors.lastname: Yokokura
authors.forename: H
authors.initials: H
authors.lastname: Kawano
authors.forename: A
authors.initials: A
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Matsuda
mesh_terms: D000042:Absorption; D000328:Adult; D001673:Biodegradation, Environmental; D018786:Bone Substitutes; D017886:Durapatite / Q000627:therapeutic use*; D005266:Femoral Neoplasms / Q000601:surgery*; D018212:Giant Cell Tumor of Bone / Q000601:surgery*; D006801:Humans; D007085:Ilium / Q000601:surgery; D008297:Male; D019736:Prostheses and Implants; D013696:Temperature
chemical_list: D018786:Bone Substitutes; D017886:Durapatite