Titanium molybdenum hafnium alloys for medical implants and devices

• US 5,954,724 A
• Filed: 03/27/1997
• Issued: 09/21/1999
• Est. Priority Date: 03/27/1997
• Status: Expired due to Term

• Current Assignee: James A. Davidson
• Original Assignee: James A. Davidson
• Inventors: Davidson, James A.
• Primary Examiner(s): Willse, David H.
• Application Number:
  US08/829,327
• Time in Patent Office: 908 Days
• Field of Search: 420/421, 606/76, 148/421
• US Class Current: 606/76
• CPC Class Codes: A61B 17/72 Intramedullary pins, nails or other devices A61B17/744 takes precedence
• CPC Class Codes: A61B 17/7275 with expanding cylindrical parts
• 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 17/8635 Tips of screws
• CPC Class Codes: A61B 17/866 Material or manufacture
• CPC Class Codes: A61C 8/0012 characterised by the material or composition, e.g. ceramics, surface layer, metal alloy use of specific materials A61K6/00
• 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 2/3662 Femoral shafts
• CPC Class Codes: A61F 2/367 Proximal or metaphyseal parts of shafts trochanteric devices connected to said proximal parts A61F2/30739
• 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 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 2002/2817 Bone stimulation by chemical reactions or by osteogenic or biological products for enhancing ossification, e.g. by bone morphogenetic or morphogenic proteins [BMP] or by transforming growth factors [TGF]
• CPC Class Codes: A61F 2002/3008 radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61F 2002/30332 Conically- or frustoconically-shaped protrusion and recess
• CPC Class Codes: A61F 2002/30677 Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• 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 2002/30892 : parallel
• CPC Class Codes: A61F 2002/30909 : Nets
• CPC Class Codes: A61F 2002/30922 : Hardened surfaces
• CPC Class Codes: A61F 2002/3611 : Heads or epiphyseal parts of femur
• CPC Class Codes: A61F 2002/3625 : Necks
• CPC Class Codes: A61F 2002/365 : Connections of heads to necks
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2250/0098 : radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61L 27/06 : Titanium or titanium alloys
• CPC Class Codes: A61L 27/28 : Materials for coating prostheses
• CPC Class Codes: A61L 31/022 : Metals or alloys
• CPC Class Codes: A61L 31/08 : Materials for coatings
• CPC Class Codes: A61N 1/0587 : Epicardial electrode systems; Endocardial electrodes piercing the pericardium
• CPC Class Codes: A63B 2209/00 : Characteristics of used materials
• CPC Class Codes: A63B 53/04 : Heads
• CPC Class Codes: A63B 53/047 : iron-type
• CPC Class Codes: A63B 53/12 : Metallic shafts
• CPC Class Codes: A63B 60/06 : Handles
• CPC Class Codes: A63B 60/08 : characterised by the material
• CPC Class Codes: A63B 60/10 : with means for indicating correct holding positions A63B60/12 takes precedence
• CPC Class Codes: C22C 14/00 : Alloys based on titanium
• CPC Class Codes: C22F 1/183 : of titanium or alloys based thereon
• CPC Class Codes: C23C 30/00 : Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process C23C26/00, C23C28/00 take precedence
• CPC Class Codes: F16B 35/00 : Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws F16B33/008 takes precedence; joining sheets or plates using screws with two separate threads F16B5/0275; using screws with adjustment sleeves F16B5/0283; thread cutting screws F16B25/00

Abstract

This invention describes a biocompatible, radiopaque, high-strength, low-modulus, titanium based alloy having about 2-30 weight percent Mo and up to about 30 weight percent Hf. This alloy is suitable for use in the fabrication of medical implants and devices having low modulus, improved corrosion resistance and surface hardening. To increase strength, Cr, Si and Fe can be added in small amounts as well as increasing levels of interstitial oxygen, nitrogen or carbon. To maintain low elastic modulus, Mo can be partially substituted by Nb.

Claims

1. A medical implant or device fabricated from a titanium alloy suitable for use in the fabrication of medical implants and devices, said medical implant or device comprising:

components at least partially fabricated from a metal alloy comprising;

a) titanium;

b) between about 6 to 9 weight percent molybdenum;

c) between about 6 to 9 weight percent hafnium;

wherein the alloy provides for high-strength and hardness, low elastic modulus, enhanced corrosion resistance, and surface hardening of the medical implant or device.

2. A medical implant or device of claim 1, wherein the alloy further includes up to about 3 weight percent of at least one element selected from the group consisting of iron, chromium and silicon.

3. A medical implant or device of claim 1, wherein additional interstitial strengthening of the alloy is achieved by increased levels of an element selected from the group consisting of oxygen, nitrogen and carbon.

4. A medical implant or device of claim 1, wherein the alloy composition is titanium, about 7 weight percent molybdenum and about 7 weight percent hafnium.

5. A medical implant or device of claim 1, wherein at least a portion of said implant or device is surface hardened by a process selected from the group consisting of oxidation and nitriding to form a hard, diffusion bonded, conversion surface oxide or nitride.

6. The medical implant or device of claim 1, wherein at least a portion of said implant or device is surface hardened by a process selected from the group consisting of oxygen diffusion hardening and nitrogen diffusion hardening, leaving a metallic-type appearance.

7. The medical implant or device of claims 1, 5 or 6, wherein at least a portion of a surface of the implant or device is coated with a low friction coating.

8. The medical implant or device of claims 1, 5 or 6, wherein at least a portion of a surface of the implant or device is coated with an agent to improve hemocompatibility, soft tissue attachment, or bone attachment, said agent selected from the group consisting of antibiotics, anti-thrombogenics, pro-thrombogenics, anti-inflammatories, morphogenic proteins, peptides, growth factors, and stem cells.

9. The medical implant or device of claim 1, wherein the alloy is hot or cold mechanically worked in order to optimize the grain size, strength, low elastic modulus, and toughness of the alloy.

10. A medical implant or device fabricated from a titanium alloy suitable for use in the fabrication of medical implants and devices, said medical implant or device comprising:

components at least partially fabricated from a metal alloy comprising;

a) titanium;

b) 2 weight percent molybdenum;

c) 6 weight percent hafnium;

d) 10 weight percent niobium;

wherein the alloy provides for enhanced strength and hardness, low modulus, corrosion resistance and surface hardening of the medical implant or device.

11. The medical implant or device of claim 10, wherein the alloy further includes up to about 3 weight percent of at least one element selected from the group consisting of iron, chromium, and silicon.

12. The medical implant or device of claim 10, wherein additional interstitial strengthening of the alloy is achieved by an increase in the level of an element selected from the group consisting of oxygen, nitrogen and carbon.

13. The medical implant or device of claim 10, wherein at least a portion of said implant or device is surface hardened by a process selected from the group consisting of oxidation and nitriding to form a hard, diffusion bonded, conversion surface oxide or nitride.

14. The medical implant or device of claims 10, 12 or 13, wherein at least a portion of said implant or device is surface hardened by a process selected from the group consisting of oxygen diffusion hardening and nitrogen diffusion hardening leaving a metallic-type appearance.

15. The medical implant or device of claim 10, wherein at least a portion of a surface of the implant or device is coated with a low friction coating.

16. The medical implant or device of claim 10, wherein at least a portion of a surface of the implant or device is coated to improve hemocompatibility, soft tissue attachment, or bone attachment with an agent selected from the group consisting of antibiotics, anti-thrombogenic agents, pro-thrombogenic agents, anti-inflammatory agents, morphogenic proteins, peptides, growth factors, and stem cells.

17. The medical implant or device of claim 10, wherein the alloy is hot or cold mechanically worked in order to optimize the grain size, strength, low elastic modulus, and toughness of the alloy.

18. A titanium alloy suitable for use in non-medical device applications comprising;

components at least partially fabricated from a metal alloy comprising;

a) titanium;

b) between about 6 to 9 weight percent molybdenum;

c) between about 6 to 9 weight percent hafnium;

wherein the alloy provides for high-strength and hardness, low elastic modulus, enhanced corrosion resistance, and surface hardening.

19. A titanium alloy suitable for use in non-medical device applications comprising;

components at least partially fabricated from a metal alloy comprising;

a) titanium;

b) 2 weight percent molybdenum;

c) 6 weight percent hafnium;

d) 10 weight percent niobium;

wherein the alloy provides for enhanced strength and hardness, low modulus, corrosion resistance and surface hardening.

20. The titanium alloy of claim 19, wherein the alloy further includes up to about 3 weight percent of at least one element selected from the group consisting of iron, chromium and silicon.