Implants incorporating nanotubes and methods for producing the same

• US 20060229715A1
• Filed: 03/29/2005
• Published: 10/12/2006
• Est. Priority Date: 03/29/2005
• Status: Abandoned Application

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Inventors: Rouleau, Jeffrey P., Istephanous, Naim
• Application Number:
  US11/092,603
• Publication Number:
  US 20060229715A1
• Time in Patent Office: Days
• US Class Current: 623/1.460
• CPC Class Codes: A61B 17/80 Cortical plates , i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61F 2/0077 Special surfaces of prostheses, e.g. for improving ingrowth A61F2/30767 takes precedence
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/2803 for mandibular reconstruction temporo-mandibular joints A61F2/3099; bone plates for the jaw A61B17/8071
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/40 for shoulders
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30677 Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• CPC Class Codes: A61F 2002/30808 parallel
• CPC Class Codes: A61F 2002/3084 Nanostructures
• CPC Class Codes: A61F 2002/30892 parallel
• CPC Class Codes: A61F 2002/30925 etched
• CPC Class Codes: A61F 2002/30929 having at least two superposed coatings
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0067 : Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 : Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00089 : Zirconium or Zr-based alloys
• CPC Class Codes: A61F 2310/00095 : Niobium or Nb-based alloys
• CPC Class Codes: A61F 2310/00131 : Tantalum or Ta-based alloys
• CPC Class Codes: A61F 2310/00598 : Coating or prosthesis-covering structure made of compounds based on metal oxides or hydroxides
• CPC Class Codes: A61F 2310/00604 : Coating made of aluminium oxide or hydroxides
• CPC Class Codes: A61F 2310/00616 : Coating made of titanium oxide or hydroxides
• CPC Class Codes: A61F 2310/00628 : Coating made of cobalt oxide or hydroxides
• CPC Class Codes: A61F 2310/00634 : Coating made of zirconium oxide or hydroxides
• CPC Class Codes: A61F 2310/0064 : Coating made of niobium oxide or hydroxides
• CPC Class Codes: A61F 2310/00658 : Coating made of tantalum oxide or hydroxides
• CPC Class Codes: A61L 2400/12 : Nanosized materials, e.g. nanofibres, nanoparticles, nanowires, nanotubes; Nanostructured surfaces
• CPC Class Codes: A61L 2400/18 : Modification of implant surfaces in order to improve biocompatibility, cell growth, fixation of biomolecules, e.g. plasma treatment
• CPC Class Codes: A61L 27/04 : Metals or alloys
• CPC Class Codes: A61L 27/50 : Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61L 31/022 : Metals or alloys
• CPC Class Codes: A61L 31/14 : Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials

Abstract

A surface-modified implant comprising a plurality of nanotubes and a process for preparing the surface-modified implant. The metal-containing surface of the implant is modified using an electrochemical anodization process to create a plurality of nanotubes formed of an oxide of the metal on at least a surface of the implant.

Claims

1. A surface modified implant having at least a metal-containing surface, comprising a plurality of nanotubes on the surface, where the nanotubes are comprised of an oxide of the metal-containing surface.

2. The surface modified implant of claim 1, where the metal-containing surface comprises a metal selected from the group consisting of titanium, titanium alloys, tantalum, tantalum alloys, stainless steel alloys, cobalt-based alloys, cobalt-chromium alloys, cobalt-chromium-molybdenum alloys, niobium alloys, and zirconium alloys.

3. The surface modified implant of claim 1, where the nanotubes comprise oxides of a metal or alloy selected from the group consisting of titanium, titanium alloys, tantalum, tantalum alloys, stainless steel alloys, cobalt-based alloys, cobalt-chromium alloys, cobalt-chromium-molybdenum alloys, niobium alloys, and zirconium alloys.

4. The surface modified implant of claim 1, where the metal-containing surface comprises commercially pure titanium and the nanotubes comprise titanium oxide.

5. The surface modified implant of claim 1, where the metal-containing surface comprises a titanium alloy and the nanotubes comprise titanium oxide.

6. The surface modified implant of claim 5, where the titanium alloy is Ti-6Al-4V and the nanotubes comprises titanium oxide, aluminum oxide, vanadium oxide, or mixtures and combinations thereof.

7. The surface modified implant of claim 1, where the inner pore diameter of the nanotubes is between about 15 nanometers and about 100 nanometers.

8. The surface modified implant of claim 1, where the outer pore diameter of the nanotubes is between about 15 nanometers and about 200 nanometers.

9. The surface modified implant of claim 1, where the height of the nanotubes is between about 15 nanometers and about 5000 nanometers.

10. The surface modified implant of claim 1, where the nanotubes are formed on the metal-containing surface by an electrochemical anodization process.

11. The surface modified implant of claim 1, where the surface modified implant is an implant selected from the group consisting of a bone implant, stent, drug depot, and fusion cage.

33. The surface modified implant of claim 1, where the implant additionally comprises an implant body to which the metal-containing surface is attached.

34. The surface modified implant of claim 33, where the metal-containing surface is a metal layer covering all or a portion of the surface of the implant.

35. The surface modified implant of claim 34, where the metal layer is attached to the implant body by cladding the implant body with the metal layer, by depositing the metal layer by sputtering, or by depositing the metal layer by electroplating the metal layer to the implant body.

12. A process for modifying a metal-containing surface of an implant to form a plurality of oxide nanotubes on the surface of the implant, comprising:

providing an electrolyte solution;

providing a cathode;

immersing the implant in the electrolyte solution; and

applying a voltage between the implant and the cathode in the electrolyte solution.

13. The process of claim 12, where the metal-containing surface of the implant comprises titanium or a titanium alloy.

14. The process of claim 12, where the oxide nanotubes comprise titanium oxide or oxides of a titanium alloy.

15. The process of claim 12, where the electrolyte solution comprises chromic acid and hydrofluoric acid.

16. The process of claim 12, where the voltage between the implant and the cathode is between about 1 V and about 40 V.

17. The process of claim 12, where a biological agent or additive is adsorbed onto or incorporated into the modified surface of the implant.

18. The process of claim 12, where the implant is an implant selected from the group consisting of a bone implant, stent, drug depot, and fusion cage.

19. A process for modifying the surface of an implant, comprising:

providing an implant comprising at least a surface containing titanium or titanium alloy;

immersing the implant and a cathode in an acidic electrolyte solution including hydrofluoric acid; and

applying an electrical potential between the implant and the cathode;

wherein a plurality of nanotubes of titanium oxide or oxides of the titanium alloy are formed on the surface of the implant.

20. The process of claim 19, where the concentration of hydrofluoric acid in the electrolyte solution is between about 0.5% by weight and about 1.5% by weight.

21. The process of claim 19, where the electrolyte solution comprises a solution of chromic acid and hydrofluoric acid.

22. The process of claim 21, where the concentration of chrornic acid in the electrolyte solution is about 0.5 moles per liter of water.

23. The process of claim 19, where the electrical potential is between about 1 V and about 40 V.

24. The process of claim 23, where the electrical potential is about 20 V.

25. The process of claim 19, where the implant is cleaned before immersing the implant in the electrolyte solution.

26. The process of claim 19, where the implant is annealed after formation of the nanotubes on the surface of the implant.

27. The process of claim 26, where the implant is annealed at a temperature less than about 580°

C.

28. The process of claim 27, where the implant is annealed at a temperature between about 280°

C. and about 430°

C.

29. The process of claim 27, where the implant is annealed at a temperature between about 430°

C. and about 580°

C.

30. The process of claim 19, where a biological agent or additive is adsorbed onto or incorporated into the modified surface of the implant.

31. The process of claim 30, where the biological agent or additive is selected from the group consisting of sugars;

nucleic acid and amino acid sequences;

vitamins;

inorganic elements;

co-factors for protein synthesis;

hormones;

endocrine tissue or tissue fragments;

synthesizers;

enzymes;

polymer cell scaffolds;

angiogenic agents;

antigenic agents;

cytoskeletal agents;

cartilage fragments;

living cells;

autogenous tissues;

somatotropin;

bone digesters;

antitumor agents and chemotherapeutics;

permeation enhancers;

bisphosphonates;

pain killers and anti-inflammatories;

antibiotics and antiretroviral drugs; and

salts.

32. The process of claim 19, where the implant is an implant selected from the group consisting of a bone implant, stent, drug depot, and fusion cage.