title: Effect of surface roughness of hydroxyapatite-coated titanium on the bone-implant interface shear strength.
abstract: We have investigated the bone-implant interface shear strength of hydroxyapatite (HA)-coated Ti-6Al-4V (HA-coating A) (roughness average, Ra = 3.4 +/- 0.5 microns) and HA-coated Ti-6Al-4V with a rougher surface (HA-coating B) (Ra = 8.4 +/- 1.8 microns). There was no significant difference between HA-coating A and HA-coating B implants with respect to the bone-implant interface shear strength as determined in push-out tests using the transcortical model in adult dogs. The bone-implant interface shear strength of bead-coated porous Ti-6Al-4V was significantly greater than that of both HA-coating A and HA-coating B implants. The failure site, as determined by scanning electron microscopy, was the coating-substrate interface, not the coating-bone interface. This indicates a need to protect the HA coating from the direct shear forces. HA coating enhances early bone growth into the porous surface of the implant. Long-term fixation should depend on bone anchoring to this porous surface. Hydroxyapatite coatings must be developed which do not obstruct the pores of the surface of the implant.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hayashi
authors.forename: T
authors.initials: T
authors.lastname: Inadome
authors.forename: H
authors.initials: H
authors.lastname: Tsumura
authors.forename: Y
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Y
authors.initials: Y
authors.lastname: Sugioka
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D004285:Dogs; D005269:Femur / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D006882:Hydroxyapatites / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D016062:Porosity; D019736:Prostheses and Implants / Q000592:standards*; D013194:Staining and Labeling; D014025:Titanium
chemical_list: D006882:Hydroxyapatites; D014025:Titanium