Porous coatings for biomedical implants

• US 8,894,824 B2
• Filed: 06/28/2005
• Issued: 11/25/2014
• Est. Priority Date: 06/28/2004
• Status: Expired due to Fees

• Current Assignee: Isoflux Incorporated
• Original Assignee: Isoflux Incorporated
• Inventors: Glocker, David A., Romach, Mark M.
• Primary Examiner(s): McDonald, Rodney
• Assistant Examiner(s): Abraham, Ibrahime A
• Application Number:
  US11/168,050
• Publication Number:
  US 20060004466A1
• Time in Patent Office: 3,437 Days
• Field of Search: 435/6, 623/1.34, 204/192.1, 204/192.15
• US Class Current: 204/192.1
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2002/30929 having at least two superposed coatings
• CPC Class Codes: A61F 2310/00407 Coating made of titanium or of Ti-based alloys
• CPC Class Codes: A61F 2310/00449 Coating made of chromium or Cr-based alloys
• CPC Class Codes: A61F 2310/00485 Coating made of zirconium or Zr-based alloys
• CPC Class Codes: A61F 2310/00497 Coating made of molybdenum or Mo-based alloys
• CPC Class Codes: A61F 2310/00544 Coating made of tantalum or Ta-based alloys
• CPC Class Codes: A61F 2310/0088 Coating made of titanium nitride
• CPC Class Codes: A61F 2310/0097 Coating or prosthesis-covering structure made of pharmaceutical products, e.g. antibiotics
• CPC Class Codes: A61L 27/306 Other specific inorganic materials not covered by A61L27/303 - A61L27/32
• CPC Class Codes: C23C 14/225 Oblique incidence of vaporised material on substrate

Abstract

A medical implant has a microscopically rough outer coating that serves to bond the implant to animal tissue. The coating is applied to the implant by physical vapor deposition. The coating preferable is applied via a generally oblique coating flux or a low energy coating flux. In some embodiments, the coating has pores. The pores can contain a drug, which can diffuse over a period of time. The coating may be partially nonporous to protect the implant from corrosion. The coating can have an outer porous layer that can bond with animal tissue easily.

Claims

1. A process for depositing a coating on a biomedical implant comprising the steps of:

placing the biomedical implant in a sputter coating system containing at least two cylindrical sputter targets each comprising a volume defined by respective outer circular planes and an inner surface of the target and a sputtering material disposed on the inner surface, the at least two cylindrical sputter targets spaced apart so that each respective volume does not overlap, the biomedical implant being positioned between and outside of the volumes of the at least two cylindrical sputter targets, wherein the biomedical implant is positioned greater than or equal to 5 cm and less than or equal to 15 cm from the at least two cylindrical sputter targets;

maintaining a background pressure of gas in the sputter coating system, wherein the background pressure of gas ranges from 3.4 mTorr to 18 mTorr;

applying a voltage to the at least two cylindrical sputter targets to cause sputtering; and

sputtering for a period of time to produce a continuous coating on the implant, said continuous coating is a Zone 1 coating and comprises columnar structures and pores, wherein said pores occur within said continuous coating itself.

2. The process of claim 1 wherein the pores have a diameter between 10 nm and 1000 nm.

3. The process of claim 1 wherein the pores vary in diameter.

4. The process of claim 1 wherein the coating comprises tantalum, titanium nitride, titanium, molybdenum, chromium or zirconium.

5. The process of claim 1 wherein the coating is configured to serve as a bonding layer between the implant and bone.

6. The process of claim 1 wherein the coating is applied to the implant via one of a generally oblique coating flux or a low energy coating flux.

7. The process of claim 1 further comprising a second coating applied to the implant.

8. The process of claim 7 wherein the second coating is applied directly to the implant.

9. The process of claim 8 wherein the second coating protects the implant from corrosion.

10. The process of claim 8 wherein the second coating in nonporous.

11. The process of claim 1 wherein the coating has a thickness between 0.1 and 10 micrometers.

12. The process of claim 1 wherein the coating comprises at least one porous portion and at least one nonporous portion.

13. The process of claim 12 wherein the porous portion coats the nonporous portion.

14. The process of claim 1 further comprising a drug within the pores.

15. The process of claim 1 wherein said step of sputtering comprises sputtering a plurality of atoms and at least a portion of said plurality of atoms undergo collisions with said background pressure of gas whereby said at least a portion of said plurality of atoms lose energy and directionality.

16. The process of claim 1 wherein the continuous coating is formed on at least a portion of the implant to improve biomedical compatibility.

17. The process of claim 1 wherein the continuous coating comprises a metal.

18. The process of claim 1 wherein the biomedical implant is positioned midway between the volumes of the at least two cylindrical sputter targets.

19. A process for depositing a coating on a biomedical implant comprising the steps of:

placing the biomedical implant in a sputter coating system containing at least two cylindrical sputter targets each comprising a volume defined by respective outer circular planes and an inner surface of the target and a sputtering material disposed on the inner surface, the at least two cylindrical sputter targets spaced apart so that each respective volume does not overlap, the biomedical implant being positioned between and outside of the volumes of the at least two cylindrical sputter targets, wherein the biomedical implant is positioned greater than or equal to 5 cm and less than or equal to 15 cm from the at least two cylindrical sputter targets;

maintaining a background pressure of gas in the sputter coating system, wherein the background pressure of gas ranges from 3.4 mTorr to 18 mTorr;

applying a voltage to the at least two cylindrical sputter targets to cause sputtering; and

sputtering for a period of time to produce a continuous coating on the implant, said continuous coating is a Zone 1 coating and comprises columnar structures and pores wherein said pores occur within said continuous coating itself and wherein the coating is applied to the implant via one of a generally oblique coating flux or a low energy coating flux.

20. The process of claim 19 wherein the continuous coating is formed on at least a portion of the implant to improve biomedical compatibility.

21. The process of claim 19 further comprising a drug within the pores.

22. The process of claim 19 wherein the continuous coating comprises a metal.

23. The process of claim 19 wherein the biomedical implant is positioned midway between the volumes of the at least two cylindrical sputter targets.