Biocompatible low modulus medical implants

• US 5,545,227 A
• Filed: 06/20/1994
• Issued: 08/13/1996
• Est. Priority Date: 12/21/1989
• Status: Expired due to Term

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Smith & Nephew Richards Incorporated (Smith & Nephew PLC)
• Inventors: Kovacs, Paul, Davidson, James A.
• Primary Examiner(s): ISABELLA, DAVID J
• Application Number:
  US08/262,226
• Time in Patent Office: 785 Days
• Field of Search: 623/16, 623/18, 623/20, 623/22, 623/23, 623/66, 606/76
• US Class Current: 623/23.53
• CPC Class Codes: A61B 17/72 Intramedullary pins, nails or other devices A61B17/744 takes precedence
• CPC Class Codes: A61B 17/74 Devices for the head or neck or trochanter of the femur trochanteric devices connected to the proximal part of an endoprosthetic femoral shaft A61F2/30739; endoprosthetic internal fixation devices for the head or neck of the femur A61F2/3601
• 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: A61B 2017/22038 with a guide wire
• CPC Class Codes: A61C 7/12 Brackets; Arch wires; Combinations thereof; Accessories therefor
• 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 2/0077 Special surfaces of prostheses, e.g. for improving ingrowth A61F2/30767 takes precedence
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• 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 2002/30922 Hardened surfaces
• CPC Class Codes: A61F 2002/3631 with an integral complete or partial peripheral collar or bearing shoulder at its base
• CPC Class Codes: A61F 2002/368 with lateral apertures, bores, holes or openings, e.g. for reducing the mass, for receiving fixation screws or for communicating with the inside of a hollow shaft
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/0058 Coating made of diamond or of diamond-like carbon DLC
• CPC Class Codes: A61F 2310/00616 Coating made of titanium 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: A61F 2310/00748 : Coating made of titanium carbide
• CPC Class Codes: A61F 2310/00766 : Coating made of zirconium carbide
• CPC Class Codes: A61F 2310/00772 : Coating made of niobium carbide
• CPC Class Codes: A61F 2310/0088 : Coating made of titanium nitride
• CPC Class Codes: A61F 2310/00892 : Coating made of zirconium nitride
• CPC Class Codes: A61F 2310/00898 : Coating made of niobium nitride
• CPC Class Codes: A61L 27/06 : Titanium or titanium alloys
• CPC Class Codes: A61L 27/507 : for artificial blood vessels apparatus for applying cells on a blood vessel prosthesis A61F2/062
• CPC Class Codes: A61L 31/022 : Metals or alloys
• CPC Class Codes: A61L 33/022 : Metal or alloys
• CPC Class Codes: A61M 2025/0062 : having features to improve the sliding of one part within another by using lubricants or surfaces with low friction
• CPC Class Codes: A61M 25/09 : Guide wires
• CPC Class Codes: A61N 1/05 : for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/056 : Transvascular endocardial electrode systems
• CPC Class Codes: C22C 14/00 : Alloys based on titanium

Abstract

This invention relates generally to high strength, low modulus, metallic medical implants and, in particular, a titanium alloy useful in their fabrication which has a relatively low modulus of elasticity (e.g. closer to that of bone than other typically-used metal alloys) and which does not include any elements which have been shown or suggested as having short term or long term potential adverse effect from a standpoint of biocompatibility. The titanium alloy includes niobium and zirconium in specified amounts with tantalum an optional substitute for niobium.

Claims

1. A biocompatible metallic implant, the implant at least partially fabricated from an alloy consisting essentially of the following alloying components:

(a) titanium;

(b) from about 10 to about 20 wt. % as the sum of metals selected from the group consisting of niobium and tantalum; and

(c) an amount of zirconium sufficient to act as a beta stabilizer by slowing the transformation of beta;

wherein toxic elements are excluded except for those trace amounts of impurities and interstitials present in the alloying components or picked up during fabrication of the implant.

2. The implant of claim 1, wherein the alloy has an elastic modulus of from about 60 to about 90 GPa.

3. The implant of claim 1, wherein the alloy includes about 74 wt. % titanium, about 13 wt. % niobium and about 13 wt. % zirconium.

4. The implant of claim 1 wherein the alloying components are titanium, about 10 to about 20 wt. % niobium, and less than about 20 wt. % zirconium.

5. The implant of claim 1, wherein the alloy has a modulus of elasticity of less than about 85 GPa.

6. The implant of claim 1 further comprising a wear resistant coating on outer surfaces.

7. A low modulus, biocompatible, metallic implant for implantation in a human body, the implant at least partially fabricated from an alloy consisting of:

(a) titanium;

(b) from about 10 to about 20 wt. % as the sum of metals selected from the group consisting of niobium and tantalum; and

(c) an amount of zirconium sufficient to act as a beta stabilizer by slowing the transformation of beta.

8. The implant of claim 7 wherein the alloy consists of 74 wt. % titanium, 13 wt. % niobium, and 13 wt. % zirconium.

9. The implant of claim 7 further comprising a wear resistant coating on surfaces.

10. The implant of claim 7 wherein the zirconium amount is less than about 20 wt. %.

11. A biocompatible, metallic implant for implantation in a human body, the implant at least partially fabricated from an alloy consisting essentially of the following alloying components:

(a) titanium;

(b) from about 35 to about 50 wt. % of the sum of metals selected from the group consisting of niobium and tantalum; and

(c) an amount of zirconium sufficient to act as a beta stabilizer by slowing the transformation of beta;

wherein toxic elements are excluded except for those trace amounts of impurities and interstitials present in the alloying components or picked up during fabrication of the implant.

12. The implant of claim 11 wherein the amount of zirconium is less than about 20 wt. %.

13. The implant of claim 11 wherein the modulus of elasticity of the alloy is less than about 85 GPa.

14. The implant of claim 11 further comprising a wear resistant coating on outer surfaces.