MEDICAL IMPLANTS HAVING A POROUS COATED SUFACE

• US 20100074789A1
• Filed: 07/21/2009
• Published: 03/25/2010
• Est. Priority Date: 09/25/2008
• Status: Active Grant

• Current Assignee: Smith & Nephew Incorporated (Smith & Nephew PLC)
• Original Assignee: Smith & Nephew Incorporated (Smith & Nephew PLC)
• Inventors: HEUER, DANIEL A., Jani, Shilesh C., Scott, Marcus L., Pawar, Vivek
• Granted Patent: US 8,361,381 B2
• Time in Patent Office: Days
• US Class Current: 419/8
• CPC Class Codes: B22F 2201/03 Oxygen
• CPC Class Codes: B22F 2201/10 Inert gases
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/15 Hot isostatic pressing
• CPC Class Codes: B22F 7/004 comprising at least one non-porous part
• CPC Class Codes: B22F 7/08 with one or more parts not made from powder B22F7/062 takes precedence

Abstract

A process for making a diffusion hardened medical implant having a porous surface is disclosed. The medical implant is made by a hot isostatic pressing process which simultaneously forms that porous surface and the diffusion hardened surface.

Claims

1. A method of making a medical implant having a porous surface and a blue, blue-black, or black oxidized zirconium, said method comprising:

forming a medical implant from a zirconium or zirconium alloy material;

applying a HIP sintering material to at least one surface of said implant;

attaching an enclosure around a surface of said implant such that the attached enclosure contains said HIP sintering material, said enclosure having an inner surface which is proximal to said implant surface and an outer surface which is distal to said implant surface and wherein the enclosure is formed of a collapsible material;

evacuating substantially all air from said enclosure;

sealing the evacuated enclosure;

placing said implant, said HIP sintering material, and said enclosure in a HIP furnace;

pressurizing the inside of said HIP furnace to an elevated pressure in an atmosphere comprising an inert gas and oxygen, said step of pressuring comprising pressuring to a total pressure of from about 20 to about 4000 bar and a partial pressure of oxygen of from about 0.1 to about 21 mbar;

adjusting the temperature in said furnace to a temperature of from 500°

C. to 1000°

C.; and

,

causing said implant, said HIP sintering material, and said enclosure in said HIP furnace to remain exposed to said temperatures and pressures for a time sufficient to fuse said HIP sintering material together and to said surface of said implant; and

oxidize at least a portion of the surface of said implant to blue blue-black or black oxidized zirconium, said time ranging from about 30 minutes to about 10 hours; and

thereafter,

cooling said implant, said metallic beads and/or particles, and said enclosure; and

, removing said enclosure.

2. The method of claim 1, wherein said step of attaching an enclosure comprises attaching an enclosure having an inner surface comprising molybdenum.

3. The method of claim 1, wherein said step of attaching an enclosure comprises attaching an enclosure having an inner surface comprising hydroxyapatite.

4. The method of claim 1, wherein said inert gas comprises argon.

5. The method of claim 1, wherein said HIP sintering material is comprised of beads and/or particles of a US Sieve Series mesh size between 18 and 80.

6. The method of claim 1, wherein said step of adjusting the temperature in said furnace, comprises adjusting said temperature to a temperature below the temperature at which the material forming said implant, said HIP sintering material, or both said implant and HIP sintering material undergoes a change in microstructure.

7. The method of claim 1, wherein said step of applying comprises applying with HIP sintering material comprising zirconium or zirconium alloy.

8. The method of claim 7 wherein said zirconium alloy is Zr-2.5Nb.

9. The method of claim 1, wherein said step of applying comprises applying with HIP sintering material comprising titanium or titanium alloy.

10. The method of claim 9 wherein said titanium alloy is Ti-6Al-4V.

11. The method of claim 1, wherein said step of adjusting the temperature in said furnace, comprises adjusting said temperature to a temperature of 680°

C.

12. The method of claim 1, wherein said step of pressurizing comprises pressurizing with a gas comprising oxygen at a level ranging from 0.05% to 0.00005%.

14. The method of claim 1, wherein said time of exposure to fuse the HIP sintering material together and to the surface of the implant is about 4 hours.

15. The method of claim 1, further comprising the step of masking a portion of the surface of the zirconium or zirconium alloy medical implant prior to said step of placing said implant, said HIP sintering material, and said enclosure in a HIP furnace.

16. The method of claim 1, wherein

said step of applying a HIP sintering material comprises applying a HIP sintering material and a binder to said at least one surface,

said step of attaching an enclosure comprises attaching an enclosure comprising a vent,

said method further comprising the step of vacuum treating said HIP sintering material, said binder, and said implant surface.

13. The method of claim 13, wherein said oxygen in said gas is at a level of 0.0005%.

17. A method of making a medical implant having a blue blue-black or black oxidized zirconium, said method comprising:

forming a medical implant from a zirconium or zirconium alloy material;

placing said implant in a HIP furnace;

pressurizing the inside of said HIP furnace to an elevated pressure in an atmosphere comprising an inert gas and oxygen, said step of pressuring comprising pressuring to a total pressure of from about 20 to about 4000 bar and a partial pressure of oxygen of from about 0.1 to about 21 mbar;

adjusting the temperature in said furnace to a temperature of from 500°

C. to 1000°

C.; and

,

causing said implant to remain exposed to said temperatures and pressures for a time sufficient to oxidize at least a portion of the surface of said implant to blue blue-black or black oxidized zirconium, said time ranging from about 30 minutes to about 10 hours.

18. The method of claim 17, wherein said inert gas comprises argon.

19. The method of claim 17, wherein said step of adjusting the temperature in said furnace, comprises adjusting said temperature to a temperature below the temperature at which the material forming said implant undergoes a change in microstructure.

20. The method of claim 17 wherein said step of forming a medical implant from a zirconium or zirconium alloy material comprises forming said medical implant from Zr-2.5Nb alloy.

21. The method of claim 17, wherein said step of adjusting the temperature in said furnace, comprises adjusting said temperature to a temperature of 680°

C.

22. The method of claim 17, wherein said step of pressurizing comprises pressurizing with a gas comprising oxygen at a level ranging from 0.05% to 0.00005%.

23. The method of claim 22, wherein said oxygen in said gas is at a level of 0.0005%.

24. The method of claim 17, wherein said time of exposure to fuse the HIP sintering material together and to the surface of the implant is about 4 hours.

25. The method of claim 17, further comprising the step of masking a portion of the surface of the zirconium or zirconium alloy medical implant prior to said step of placing said implant in a HIP furnace.