Method and apparatus for forming porous metal implants

• US 20070196230A1
• Filed: 02/17/2006
• Published: 08/23/2007
• Est. Priority Date: 02/17/2006
• Status: Active Grant

• Current Assignee: Biomet Manufacturing, LLC (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Biomet Manufacturing, LLC (Zimmer Biomet Holdings, Inc.)
• Inventors: Janson, Isaac, Kumar, Mukesh, Meridew, Jason, Fleming, J., Schleuter, Elizabeth, Hamman, Ned
• Granted Patent: US 7,635,447 B2
• Time in Patent Office: Days
• US Class Current: 419/2
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/30907 Nets or sleeves applied to surface of prostheses or in cement
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/3859 Femoral components
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30064 Coating or prosthesis-covering structure made of biodegradable material
• CPC Class Codes: A61F 2002/30166 H-shaped or I-shaped
• CPC Class Codes: A61F 2002/30169 Pi-shaped
• CPC Class Codes: A61F 2002/302 toroidal, e.g. rings
• CPC Class Codes: A61F 2002/30205 conical
• CPC Class Codes: A61F 2002/30224 cylindrical
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/30383 made by laterally inserting a protrusion, e.g. a rib into a complementarily-shaped groove
• CPC Class Codes: A61F 2002/30451 soldered or brazed or welded
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30736 Augments or augmentation pieces, e.g. wedges or blocks for bridging a bone defect
• CPC Class Codes: A61F 2002/30827 : Plurality of grooves
• CPC Class Codes: A61F 2002/30878 : with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
• CPC Class Codes: A61F 2002/3092 : having an open-celled or open-pored structure
• CPC Class Codes: A61F 2002/30968 : Sintering
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0058 : soldered or brazed or welded
• CPC Class Codes: A61F 2230/0028 : Shapes in the form of latin or greek characters
• CPC Class Codes: A61F 2230/0047 : Pi-shaped
• CPC Class Codes: A61F 2230/0065 : toroidal, e.g. ring-shaped, doughnut-shaped
• CPC Class Codes: A61F 2230/0067 : conical
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0023 : differing in porosity
• 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 2310/00059 : Chromium or Cr-based alloys
• CPC Class Codes: A61F 2310/00131 : Tantalum or Ta-based alloys
• CPC Class Codes: A61F 2310/00592 : Coating or prosthesis-covering structure made of ceramics or of ceramic-like compounds
• CPC Class Codes: A61F 2310/00958 : Coating or prosthesis-covering structure made of bone or of bony tissue
• CPC Class Codes: A61F 2310/0097 : Coating or prosthesis-covering structure made of pharmaceutical products, e.g. antibiotics
• CPC Class Codes: A61F 2310/00976 : Coating or prosthesis-covering structure made of proteins or of polypeptides, e.g. of bone morphogenic proteins BMP or of transforming growth factors TGF
• CPC Class Codes: A61K 35/12 : Materials from mammals; Compositions comprising non-specified tissues or cells; Compositions comprising non-embryonic stem cells; Genetically modified cells vaccines or medicinal preparations containing antigens or antibodies A61K39/00
• CPC Class Codes: A61L 2300/25 : Peptides having up to 20 amino acids in a defined sequence
• CPC Class Codes: A61L 2300/406 : Antibiotics
• CPC Class Codes: A61L 2300/414 : Growth factors
• CPC Class Codes: A61L 2300/428 : Vitamins, e.g. tocopherol, riboflavin
• CPC Class Codes: A61L 2300/606 : Coatings
• CPC Class Codes: A61L 2300/64 : Animal cells
• CPC Class Codes: A61L 27/04 : Metals or alloys
• CPC Class Codes: A61L 27/54 : Biologically active materials, e.g. therapeutic substances A61L27/227 takes precedence
• CPC Class Codes: A61L 27/56 : Porous materials, e.g. foams or sponges
• CPC Class Codes: B22F 1/10 : Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
• CPC Class Codes: B22F 1/103 : containing an organic binding agent comprising a mixture of, or obtained by reaction of, two or more components other than a solvent or a lubricating agent
• CPC Class Codes: B22F 2998/10 : Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 3/02 : Compacting only
• CPC Class Codes: B22F 3/04 : by applying fluid pressure , e.g. by cold isostatic pressing [CIP]
• CPC Class Codes: B22F 3/1021 : Removal of binder or filler removal of binder from ceramics C04B35/638
• CPC Class Codes: B22F 3/1125 : involving a foaming process
• CPC Class Codes: B22F 3/1216 : Container composition
• CPC Class Codes: C01P 2004/61 : Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C09C 1/00 : Treatment of specific inorganic materials other than fibrous fillers tenebrescent materials C09K9/00; luminescent materials C09K11/00; Preparation of carbon black

Abstract

A method for providing a porous metal implant. A mixture of a biocompatible metal, a spacing agent, and a binder is provided. The mixture is formed into a shaped the spacing agent is removed to form a plurality of pores in the implant. A shaped porous metal implant is also provided.

Claims

1. A method for preparing a porous metal implant comprising:

a. preparing a mixture comprising;

i. a biocompatible metal powder;

ii. a spacing agent; and

iii. a non-polar liquid binder, wherein the spacing agent is substantially insoluble in the non-polar liquid binder;

b. forming the mixture into a shape; and

c. removing the spacing agent to form a plurality of pores within the metal implant.

2. The method of claim 1, wherein the biocompatible metal powder is selected from the group consisting of titanium, titanium alloys, cobalt, cobalt alloys, chromium, chromium alloys, tantalum, tantalum alloys, and stainless steel.

3. The method of claim 1, wherein the metal powder has a particle size of from about 5 micrometers to about 1500 micrometers.

4. The method of claim 1, wherein the spacing agent comprises hydrogen peroxide, urea, ammonium carbonate, ammonium bicarbonate, ammonium carbamate, calcium hydrogen phosphate, naphthalene, and mixtures thereof.

5. The method of claim 1, wherein the spacing agent has a particle size of from about 1 micrometer to about 1500 micrometers.

6. The method of claim 1, wherein the non-polar liquid binder and the spacing agent form a suspension.

7. The method of claim 1, wherein the non-polar liquid binder comprises d-limonene.

8. The method of claim 1, wherein the binder and the spacing agent are cohesive during formation of the mixture and removal of the spacing agent.

9. The method of claim 1, wherein the mixture is a homogenous mixture.

10. The method of claim 1, wherein forming the mixture into a shape comprises molding the mixture into a shape suitable for application to an augment site.

11. The method of claim 1, wherein forming the mixture into a shape is selected from pressing techniques selected from the group consisting of uniaxial pressing, isostatic pressing, and split die techniques.

12. The method of claim 11, wherein said forming is conducted at a temperature at or below about room temperature.

13. The method of claim 11, wherein the pressing technique is conducted at about above 150 megapascals.

14. The method of claim 13, wherein the pressing technique is conducted at above about 170 megapascals.

15. The method of claim 1, wherein removing the spacing agent comprises subliming the mixture at which the metal does not react with the spacing agent.

16. The method of claim 1, further comprising sintering the metal under vacuum pressure after removing the spacing agent.

17. The method of claim 16, further comprising at least one of shaping the implant, machining the implant, attaching the implant to a substrate, or welding the porous implant to a substrate.

18. The method of claim 1, wherein the metal powder includes at least two different sizes.

19. The method of claim 1, further comprising providing a gradient porosity in the metal implant.

20. The method of claim 19, wherein the gradient porosity is from about 1% to about 80%.

21. The method of claim 1, further comprising coating at least a surface of the porous metal implant with an agent selected from the group consisting of resorbable ceramics, resorbable polymers, antibiotics, demineralized bone matrix, blood products, platelet concentrate, allograft, xenograft, autologous and allogeneic differentiated cells or stem cells, peptides, nutrients, vitamins, growth factors, and mixtures thereof.

22. A moldable mixture for providing a porous metal implant comprising:

a. a biocompatible metal powder;

b. a spacing agent; and

c. a non-polar liquid binder, wherein the spacing agent is substantially insoluble in the non-polar liquid binder.

23. The moldable mixture according to claim 22, wherein the biocompatible metal powder comprises Ti-6AI-4V.

24. The moldable mixture according to claim 22, wherein the spacing agent comprises ammonium bicarbonate.

25. The moldable mixture according to claim 22, wherein the non-polar liquid binder is d-limonene.

26. The moldable mixture according to claim 22, wherein the difference in the sublimation of the spacing agent and the sublimation temperature of the non-polar liquid binder is less than about 200°

C.

27. The moldable mixture according to claim 22, further comprising a securing element.

28. A method of securing the moldable mixture of claim 27, comprising:

a. placing a securing element about at least a portion of the mixture;

b. molding the mixture into a formed shape while the mixture is in the securing element;

c. subliming the spacing agent and non-polar liquid binder from the formed shape;

d. removing the securing element; and

e. sintering the formed shape.

29. The method of claim 28, wherein the securing element is made of a flexible material.

30. The method of claim 29, wherein the flexible material is selected from a metal foil, rubber, or a silicone polymer.

31. The method of claim 30, wherein the flexible material is a metal foil.

32. The method of claim 28, wherein the securing element is vacuum sealed about at least a portion of the mixture.

33. The method of claim 28, wherein the securing element enhances the cohesiveness of the formed shape for at least three days.

34. A method for preparing a porous metal implant comprising:

a. preparing a mixture comprising;

i. a biocompatible metal powder;

ii. a spacing agent; and

iii. a non-polar liquid binder, wherein the spacing agent is substantially insoluble in the non-polar liquid binder;

b. forming the mixture into a shape; and

c. thermal cycling the mixture within a single heating unit to remove the spacing agent and the non-polar liquid binder and sinter the metal powder to form a plurality of pores within the metal implant.

35. The method according to claim 34, further comprising continuously maintaining the mixture in the heating unit until the metal powder combines to form the metal implant.

36. The method according to claim 34, wherein the thermal cycling comprises includes at least one sintering and at least one quenching.