Method and apparatus for use of porous implants

• US 8,266,780 B2
• Filed: 02/27/2008
• Issued: 09/18/2012
• 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: Bollinger, Mark A., May, Brian M.
• Primary Examiner(s): Bryant, David
• Assistant Examiner(s): CIGNA, JACOB JAMES
• Application Number:
  US12/038,570
• Publication Number:
  US 20080147187A1
• Time in Patent Office: 1,665 Days
• Field of Search: 294/47, 294/05, 295/07, 403/273, 623/23.3, 623/23.55, 428/613, 228/229, 228/230
• US Class Current: 29/447
• 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:

providing a substrate that comprises an implantable orthopedic component of nonporous metal;

forming a three-dimensional cavity defined by inner walls of 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 wherein the inner walls include side walls and a closed end wall, the closed end wall having a surface that faces the opening;

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, the porous metal insert having a porous metal outer surface configured to encourage ingrowth of soft tissue;

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 wherein the porous metal outer surface of the porous metal insert engages at least the closed end wall of the inner walls of the substrate.

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

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

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

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

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

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

8. The method of claim 1 wherein the porous metal insert is formed entirely of porous material.

9. The method of claim 1 wherein the porous metal insert is uniformly porous.

10. The method of claim 9 wherein an entirety of the porous metal insert is retained within the cavity.

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

providing a metal substrate that is a solid metal portion of an orthopedic implant;

cooling a three-dimensional porous metal insert below ambient temperature, the porous metal insert having a porous metal outer surface configured to encourage ingrowth of soft tissue;

reducing at least a first dimension of the insert;

inserting the cooled metal insert through an opening into a three-dimensional cavity defined by inner walls of the metal substrate, the opening having a second dimension parallel to the first dimension of the insert wherein the inner walls include side walls and a closed end wall, the closed end wall having a surface that faces the opening;

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 wherein the porous metal outer surface of the porous metal insert engages at least the closed end wall of the inner walls of the metal substrate.

12. The method of claim 11, further comprising machining the cavity into the substrate.

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

14. The method of claim 11, wherein cooling the insert further comprises immersing the insert in liquid nitrogen.

15. The method of claim 11, wherein cooling the insert comprises reducing a linear dimension of the insert by about 4-8%.

16. The method of claim 11, further comprising heating the substrate.

17. The method of claim 11 wherein the porous metal insert is uniformly porous.

18. The method of claim 11 wherein the porous metal insert is formed entirely of porous material.

19. The method of claim 18 wherein an entirety of the porous metal insert is retained within the cavity.

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

providing an orthopedic implant that comprises a substrate formed of nonporous metal;

forming an opening in the substrate, the opening having a first outer dimension along a first axis;

forming a cavity defined by inner walls of the substrate, the cavity having a second outer dimension along the first axis, the second outer dimension being greater than the first outer dimension, wherein a retaining ledge is formed on the substrate at a transition between the opening and the cavity wherein the inner walls include side walls and a closed end wall, the closed end wall having a surface that faces the opening;

forming a porous metal insert made entirely of porous metal material configured to encourage ingrowth of soft tissue and having a three-dimensional shape mateable with the cavity and a third outer dimension along the first axis greater than the first outer dimension;

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

inserting the insert through the opening; and

retaining the insert in the cavity by the retaining ledge upon return to ambient temperature wherein the porous metal insert engages at least the closed end wall of the inner walls of the substrate.

21. The method of claim 20 wherein the cavity and the insert are cylindrical.

22. The method of claim 20 wherein the cavity and the insert are prismatic.

23. The method of claim 20 wherein forming the cavity further comprises machining the cavity into the substrate.

24. The method of claim 20 wherein forming the opening and the cavity further comprises casting the opening and the cavity into the substrate.

25. The method of claim 20 wherein the ledge circumscribes the entire opening.

26. The method of claim 20 wherein the cavity is a blind bore.

27. The method of claim 20 wherein providing the substrate comprises providing a femoral hip stem.

28. The method of claim 20 wherein retaining the insert in the cavity comprises positioning a portion of the insert at a location that protrudes outside of the opening and beyond the retaining ledge.

29. The method of claim 20, further comprising heating the substrate.

30. The method of claim 20 wherein an entirety of the porous metal insert is retained within the cavity.