Orthopedic implant having a crystalline gallium-containing hydroxyapatite coating and methods for making the same

Abstract

An orthopedic implant having a metal surface and a hydroxyapatite layer comprising gallium ions therein disposed on at least part of the metal surface is described. The hydroxyapatite layer has an average crystallite size of less than about 75 nm in at least one direction and dissolves for more than 2 hours in vitro. The hydroxyapatite layer is substantially free of carbonate. The coating, which is formed on a sodium titanate surface, has increased shear strength and tensile strength. The coating is formed by a solution deposited hydroxyapatite process under inert conditions. The pH of the solution varies by less than 0.1 pH unit/hour during coating formation.

What is claimed is: 
     
         1 . A hydroxyapatite coating on a surface of an orthopedic implant, wherein the hydroxyapatite coating comprises gallium ions therein, and wherein the hydroxyapatite coating has a surface area of about 15 m 2 /g to about 200 m 2 /g. 
     
     
         2 . The hydroxyapatite coating of  claim 1 , wherein the hydroxyapatite coating is substantially free of carbonate as measured by infrared spectroscopy.