title: Scanning electron microscopy-electron probe microanalysis study of the interface between apatite and wollastonite-containing glass-ceramic and rabbit tibia under load-bearing conditions after long-term implantation.
abstract: Glass-ceramic implants containing oxy- and fluoroapatite [Ca10(PO4)6(O, F2)] and beta-wollastonite (CaSiO3) were studied under load-bearing conditions in a segmental replacement model in the tibia of the rabbit. A 16-mm segment of the middle of the tibial shaft was resected at a point distal to the junction of the tibia and the fibula. The defect was replaced by a 15 mm-long hollow, cylindrical implant that was fixed by intramedullary nailing using Kirschner wire. The implants were 9 mm in diameter and 15 mm long bearing a central hole 3.05 mm in dianeter. The rabbits used were killed 6 months, 1 year, 18 months, and 2 years after implantation. The interface between the bone and the glass-ceramic was investigated by scanning electron microscopy-electron-probe microanalysis (SEM-EPMA). None of the glass-ceramic implants broke, and the glass-ceramic had bonded directly to the bone tissue without any intervening soft tissue. A calcium-phosphorus layer (Ca-P layer) was observed at the glass-ceramic/bone interface. This layer was 30-100 microns thick at 6 months after implantation, 60-110 microns thick at 1 year after implantation, 80-200 microns thick at 18 months, and 120-350 microns thick at 2 years. At the lateral surface of the glass-ceramic uncovered by the bone, the calcium-phosphorus layer was 50-80 microns thick at 6 months after implantation, 250-450 microns thick at 1 year, 300 approximately 400 microns thick at 18 months, and 300 microns thick at 2 years. The thickness of the calcium-phosphorus layer increased moderately after long-term implantation. However, it was difficult to estimate the rate of increase in the thickness of calcium-phosphorus layer.
authors.affiliation: Department of Orthopedic Surgery, Faculty of Medicine, Kyoto University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kitsugi
authors.forename: T
authors.initials: T
authors.lastname: Yamamuro
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Oka
authors.forename: T
authors.initials: T
authors.lastname: Kokubo
authors.forename: K
authors.initials: K
authors.lastname: Okunaga
authors.forename: T
authors.initials: T
authors.lastname: Shibuya
mesh_terms: D000818:Animals; D001031:Apatites / Q000378:metabolism*; D001672:Biocompatible Materials / Q000378:metabolism*; D002130:Calcium Phosphates / Q000378:metabolism; D002516:Ceramics / Q000378:metabolism*; D004577:Electron Probe Microanalysis; D008297:Male; D008855:Microscopy, Electron, Scanning; D019736:Prostheses and Implants; D011817:Rabbits; D012824:Silicic Acid / Q000378:metabolism*; D013977:Tibia / Q000378:metabolism* / Q000502:physiology / Q000601:surgery / Q000648:ultrastructure; D013997:Time Factors; D016474:Weight-Bearing
chemical_list: D001031:Apatites; D001672:Biocompatible Materials; D002130:Calcium Phosphates; C077777:apatite-wollastonite-containing glass ceramic; D012824:Silicic Acid