Effect of surface roughness of hydroxyapatite-coated titanium on the bone-implant interface shear strength.
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.
Hayashi
K
K
Department of Orthopaedic Surgery, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Inadome
T
T
Tsumura
H
H
Nakashima
Y
Y
Sugioka
Y
Y
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
D006882:Hydroxyapatites; D014025:Titanium