Biocompatible low modulus titanium alloy for medical implants

• US 5,169,597 A
• Filed: 01/28/1991
• Issued: 12/08/1992
• 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): Roy, Upendra
• Application Number:
  US07/647,453
• Time in Patent Office: 680 Days
• Field of Search: 420/417, 420/421, 148/421, 148/133, 606/78, 606/76
• US Class Current: 428/613
• 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: 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 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 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: 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
• CPC Class Codes: Y10T 428/12479 : Porous [e.g., foamed, spongy, cracked, etc.]
• CPC Class Codes: Y10T 428/12639 : Adjacent, identical composition, components
• CPC Class Codes: Y10T 428/30 : Self-sustaining carbon mass or layer with impregnant or other layer

Abstract

A biocompatible titanium alloy with low elastic modulus containing titanium, about 10-20 wt. % or 35 to about 50 wt. % niobium and up to 20 wt. % zirconium useful for fabricating of orthopedic implants. This invention relates generally to high strength, biocompatible alloys suitable for use as a material for a medical prosthetic implant and, in particular, a titanium alloy which has a relatively low modulus of elasticity (e.g. closer to that of bone than other typically-used metal alloys) and does not include any elements which have been shown or suggested as having short term or long term potential adverse effect from a standpoint or biocompatibility.

Claims

1. In a human body wherein orthopedic implants remain for a prolonged period of time and must maintain strength and flexibility while being subjected to sustained corrosive effects of body fluids resulting in release of toxic or potentially toxic ions into surrounding tissue, the improvement wherein the implant has the alloy composition comprising:

from about 10 to about 20 wt. % niobium or from about 35 to about 50 wt. % niobium;

from about 13 to about 20 wt. % zirconium; and

the balance titanium;

said alloy composition excluding metal ions harmful to the human body and having a modulus of elasticity of less than 85 GPa.

2. The improved implant of claim 1 wherein the alloy forming the implant has an elastic modulus of from about 60 to about 85 GPa.

3. The improved implant of claim 1 consisting essentially of about 74 wt. % titanium, about 13 wt. % niobium, and about 13 wt. % zirconium.

4. The improved implants of claim 1 wherein the alloy composition includes an amount of tantalum as a β

-stabilizer sufficient to stabilize a β

-phase in the alloy composition of the implant without significantly affecting the modulus of elasticity of the implant.

5. The improved implants of claims 2 or 3 further comprising at least a partial outer surface coating comprising the oxides, carbides or nitrides of the elements selected from the group consisting of titanium, niobium and zirconium.

6. The improved implants of claims 2 or 3 further comprising at least a partial outer surface coating of amorphous diamond-like carbon.

7. The improved implants of claims 2 or 3 further comprising a surface coating of porous beads or wire mesh for the ingrowth of tissue into the surface coating to stabilize the implant in the body environment.