Bone-compatible implant and method of producing the same
By forming a bone-compatible implant wherein a groove or hole has been formed in the surface of a base material made of titanium metal or a titanium alloy at its joint with a bone tissue and the groove or hole has on the inner surface thereof an oxide film formed by heating in an oxygen-containing atmosphere, apatite is allowed to deposit on the inner surface of the groove or hole easily. Thus, an implant is provided which can be attached to a bone within a relatively short period of time even without resorting to bone cement.
1. A bone-compatible implant wherein a groove has been formed in a surface of a base material made of titanium metal or a titanium alloy at a joint with a bone tissue and the groove has an oxide film on an inner surface thereof;
wherein the base material is substantially free from aluminum or vanadium,
wherein the groove has a width (W) of 0.25 to 0.8 mm and a depth (D) of 0.25 to 1 mm, and a ratio (D/W) of the depth (D) to the width (W) is from 0.1 to 2, and
wherein the oxide film has a thickness of 0.01 to 1 μm and has been formed by heating in an oxygen-containing atmosphere.
2. The bone-compatible implant according to claim 1 , wherein the groove has a cross sectional shape which is rectangle, trapezoid, U-shape or V-shape.
3. The bone-compatible implant according to claim 1 , wherein the base material is made of a titanium alloy which contains titanium with a content of 50% by weight or more and at least one metal selected from zirconium, tantalum, niobium and palladium with a combined content of 0.1 to 50% by weight.
4. A method for producing the bone-compatible implant according to claim 1 , wherein titanium metal or a titanium alloy is formed into a desired shape, then the groove is formed in the surface of the titanium metal or titanium alloy at the joint with a bone tissue, and subsequently the oxide film is formed on the surface by heating the surface in an oxygen-containing atmosphere.
5. The method for producing a bone-compatible implant according to claim 4 , wherein the groove is formed by at least one machining method selected from the group consisting of mechanical cutting, wire electric discharge machining, laser machining, water jet machining, press working, ultrasonic machining, and etching.
6. The method for producing a bone-compatible implant according to claim 4 , wherein polishing treatment of the surface is conducted after forming of the groove.
7. The method for producing a bone-compatible implant according to claim 4 , wherein the heating temperature in the forming of the oxide film is 300 to 700° C.
8. The method for producing a bone-compatible implant according to claim 4 , wherein treatment of the oxide film with water or water vapor at 80 to 300° C. is conducted after the forming of the oxide film.
9. The method for producing a bone-compatible implant according to claim 4 , wherein immersion of the oxide film into an aqueous solution containing a calcium ion and a phosphate ion is conducted after the forming of the oxide film.