Method And Apparatus For Use Of Porous Implants

• US 20080147187A1
• Filed: 02/27/2008
• Published: 06/19/2008
• Est. Priority Date: 04/21/2005
• Status: Active Grant

• Current Assignee: Biomet Manufacturing, LLC (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Biomet Manufacturing, LLC (Zimmer Biomet Holdings, Inc.)
• Inventors: May, Brian M., Bollinger, Mark A.
• Granted Patent: US 8,266,780 B2
• Time in Patent Office: Days
• US Class Current: 623/11.11
• 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 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30077 shrinkable
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30187 D-shaped or half-disc-shaped
• CPC Class Codes: A61F 2002/30224 cylindrical
• CPC Class Codes: A61F 2002/30242 spherical
• CPC Class Codes: A61F 2002/30253 ellipsoidal or ovoid
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/30263 cubical
• CPC Class Codes: A61F 2002/30276 frustopyramidal
• CPC Class Codes: A61F 2002/30329 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2002/30448 using adhesives
• CPC Class Codes: A61F 2002/30451 soldered or brazed or welded
• CPC Class Codes: A61F 2002/30535 Special structural features of bone or joint prostheses not otherwise provided for
• CPC Class Codes: A61F 2002/30677 Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• CPC Class Codes: A61F 2002/30733 Inserts placed into an endoprosthetic cavity, e.g. for modifying a material property
• CPC Class Codes: A61F 2002/30736 Augments or augmentation pieces, e.g. wedges or blocks for bridging a bone defect
• CPC Class Codes: A61F 2002/30785 parallel
• CPC Class Codes: A61F 2002/30795 Blind bores, e.g. of circular cross-section
• CPC Class Codes: A61F 2002/30915 : made of a stack of bonded perforated sheets, grids or wire meshes
• CPC Class Codes: A61F 2002/30952 : using CAD-CAM techniques or NC-techniques
• CPC Class Codes: A61F 2002/30967 : Diffusion bonding
• CPC Class Codes: A61F 2002/30968 : Sintering
• CPC Class Codes: A61F 2002/3097 : using laser
• 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 2210/0066 : shrinkable
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/005 : using adhesives
• CPC Class Codes: A61F 2220/0058 : soldered or brazed or welded
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2230/0034 : D-shaped
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2230/0071 : spherical
• CPC Class Codes: A61F 2230/0076 : ellipsoidal or ovoid
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2230/0084 : cubical
• CPC Class Codes: A61F 2230/0086 : Pyramidal, tetrahedral, or wedge-shaped
• CPC Class Codes: A61F 2250/0024 : made from both porous and non-porous parts, e.g. adjacent parts
• 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: Y10T 29/49861 : Sizing mating parts during final positional association
• CPC Class Codes: Y10T 29/49865 : by temperature differential [e.g., shrink fit]

Abstract

An orthopedic implant. The implant includes a metal portion having an internal three-dimensional cavity, the cavity having an opening to an outer surface of the metal portion, a ledge circumferentially surrounding at least a portion of the opening, and a porous metal insert formed in a three-dimensional shape conforming to the shape of the cavity and enclosed by the cavity without being bonded to the cavity. The insert is retained inside the cavity by the ledge.

Claims

1. A method for attaching a metal insert to a substrate, the method comprising:

forming a three-dimensional cavity in the substrate, the cavity having a first dimension along a first axis, the cavity defining an opening to an outer surface of the substrate, the opening at least partially bounded by a ledge and having a second dimension along the first axis, the first dimension greater than the second dimension;

forming a porous metal insert having a three-dimensional shape mateable with the cavity and a third dimension along the first axis greater than the second dimension;

cooling the insert below ambient temperature until the third dimension is equal or smaller than the second dimension;

inserting the insert through the opening; and

retaining the insert in the cavity by the ledge upon return to ambient temperature.

2. The method of claim 1, wherein the substrate is an implantable orthopedic component of nonporous metal.

5. The method of claim 1, wherein forming the cavity further comprises machining the cavity into the substrate.

6. The method of claim 1, wherein forming the cavity further comprises casting the cavity into the substrate.

7. The method of claim 1, wherein the ledge circumscribes the entire opening.

8. The method of claim 1, wherein the cavity is a blind bore.

3. The method of 1, wherein the cavity and the insert are cylindrical.

4. The method of 1, wherein the cavity and the insert are prismatic.

9. A method for attaching a porous metal insert to a metal substrate, the method comprising:

cooling a three-dimensional porous metal insert below ambient temperature;

reducing at least a first dimension of the insert;

inserting the cooled metal insert through an opening into a three-dimensional cavity of a metal substrate, the opening having a second dimension parallel to the first dimension of the insert;

returning the metal insert to ambient temperature;

returning the first dimension to a length greater than the second dimension; and

retaining the metal insert in the cavity of the substrate.

10. The method of claim 9, further comprising machining the cavity into the substrate.

11. The method of claim 9, further comprising casting the cavity into the substrate.

12. The method of claim 9, wherein cooling the insert further comprises immersing the insert in liquid nitrogen.

13. The method of claim 9, wherein the metal substrate is a solid metal portion of an orthopedic implant.

14. The method of claim 9, wherein cooling the insert comprises reducing a linear dimension of the insert by about 4-8%.

15. The method of claim 9, further comprising heating the substrate.

16. An orthopedic implant comprising:

a metal portion having an internal three-dimensional cavity, the cavity having an opening to an outer surface of the metal portion;

a ledge circumferentially surrounding at least a portion of the opening; and

a porous metal insert formed in a three-dimensional shape conforming to the shape of the cavity and enclosed by the cavity without being bonded to the cavity, the insert retained inside the cavity by the ledge.

17. The implant of claim 16, wherein the metal insert has a first dimension greater than a corresponding second dimension of the ledge at ambient temperature.

18. The implant of claim 17, wherein the first dimension is less than the second dimension when the insert is cooled in liquid nitrogen.

19. The implant of claim 16, wherein the insert and the cavity are cylindrical in shape.

20. The implant of claim 16, wherein the insert and the cavity are prismatic in shape.

21. The implant of claim 16, wherein the insert is porous titanium.

22. The implant of claim 21, wherein the metal portion of the implant is a nonporous solid metal.

23. The implant of claim 22, wherein the solid metal is CoCrMo.

24. The implant of claim 16, wherein the metal portion is a portion of a femoral component.

25. The implant of claim 16, wherein the ledge surrounds substantially entirely the opening.

26. The implant of claim 16, wherein the cavity is a blind bore.