title: In vivo biocompatibility and degradation behavior of Mg alloy coated by calcium phosphate in a rabbit model.
abstract: This study is conducted to investigate the biocompatibility and biodegradation behavior of calcium phosphate-coated Mg alloy in vivo. Calcium phosphate (Ca-P) was coated on the Mg alloy (AZ31) by a chemical process. Samples of Ca-P coated rods, the naked alloy rods, and degradable polymer as controls were implanted into the thighbone of rabbits to investigate the bone response at the early stage. The reduction in implant volume was determined by micro-computed tomography and three-dimensional reconstruction of the remaining Mg alloy segmented from the bone matrix. It was observed that the biodegradation rate of naked Mg implant is faster than that of the coated ones. The bone-implant interface was characterized in sections by scanning electron microscopy with energy-dispersive spectroscopy. Biodegradation or reaction layer was formed on the surface of Mg alloy implants and direct contact with the surrounding bone. The layer was mainly composed of Ca, P, O, and Mg. After 8 weeks of post-operation, paraffin sections were generated for histomorphologic analysis; 100% implants were fixed and no inflammation was observed. Histological analysis showed that new bone tissue is formed around the Mg implants, and no fibrous capsule was found. Blood examination showed that the biodegradation of the Mg implant caused little change to blood composition. Ca-P coating on Mg alloy substrate might be an effective method to reduce the biodegradation rate of Mg alloy in vivo and improve the surface bioactivity of Mg alloy implants.
authors.affiliation: Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: J X
authors.initials: JX
authors.lastname: Yang
authors.forename: F Z
authors.initials: FZ
authors.lastname: Cui
authors.forename: I-S
authors.initials: IS
authors.lastname: Lee
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: Q S
authors.initials: QS
authors.lastname: Yin
authors.forename: H
authors.initials: H
authors.lastname: Xia
authors.forename: S X
authors.initials: SX
authors.lastname: Yang
mesh_terms: D020341:Absorbable Implants; D000497:Alloys / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001863:Bone Screws; D002130:Calcium Phosphates / Q000737:chemistry / Q000378:metabolism*; D020099:Coated Materials, Biocompatible / Q000737:chemistry / Q000378:metabolism*; D005269:Femur / Q000254:growth & development / Q000601:surgery; D020007:Implants, Experimental; D008274:Magnesium / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D010012:Osteogenesis; D011817:Rabbits; D013499:Surface Properties
chemical_list: D000497:Alloys; D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D008274:Magnesium