Method and apparatus for use of porous implants

• US 8,197,550 B2
• Filed: 09/14/2009
• Issued: 06/12/2012
• 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: Brown, David R., Meridew, Jason D., Ronk, Robert M., Hershberger, Troy W.
• Primary Examiner(s): Willse, David H
• Assistant Examiner(s): BLANCO, JAVIER G
• Application Number:
  US12/559,230
• Publication Number:
  US 20100004754A1
• Time in Patent Office: 1,002 Days
• Field of Search: None
• US Class Current: 623/22.32
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/4609 of acetabular cups
• CPC Class Codes: A61F 2002/30535 Special structural features of bone or joint prostheses not otherwise provided for
• CPC Class Codes: A61F 2250/0058 Additional features; Implant or prostheses properties not otherwise provided for

Abstract

An orthopedic prosthesis for implantation into a bone of a patient includes a porous metal shell adapted to be affixed within the bone. The porous metal shell includes an outer surface adapted to receive bone ingrowth and an inner surface adapted to engage a liner. The porous metal shell is porous from the outer surface to the inner surface. A non-porous member may be affixed to the porous metal shell. The non-porous member may include a piercing member extending from the outer surface, the piercing member adapted to penetrate the bone in an implanted position. The non-porous member may include spikes or fins. In one example, the piercing member may define a reduced material cross section at an interface with the outer surface of the porous metal shell. The piercing member may be adapted to be broken at the reduced material cross section and removed from the porous metal shell.

Claims

1. An acetabular cup for implantation into an acetabulum of a patient, the acetabular cup comprising:

an integrally formed shell having an outer hemispherical portion comprising a first porous metal layer adapted to receive bone ingrowth after implantation, an inner hemispherical portion comprising a second porous metal layer; and

a thin solid metal intermediate hemispherical portion defining a non-porous and continuous barrier between said outer and inner hemispherical portions;

at least one bone screw adapted to be intra-operatively inserted through the shell from the inner portion to the outer portion, the at least one bone screw adapted to pierce the barrier; and

a bearing liner affixed to the inner portion;

wherein the barrier inhibits wear debris particles from migrating from the inner portion to the outer portion;

wherein the outer portion defines a radial rim, wherein the intermediate portion includes an annular collar affixed around the radial rim;

wherein the intermediate portion has a thickness less than 50% of either of a thickness of the inner portion and a thickness of the outer portion;

wherein the porosity of the first porous metal layer is distinct from the porosity of the second porous metal layer.

2. The acetabular cup of claim 1 wherein the intermediate portion has a thickness less than 25% of either of a thickness of the inner portion and a thickness of the outer portion.

3. The acetabular cup of claim 1 wherein the inner portion includes integrally molded polyethylene.

4. The acetabular cup of claim 1 wherein the integrally formed shell defines a hemispherical section and where the fixation member includes at least one bone screw that is adapted to be received at any desired location around the hemispherical section.

5. The acetabular cup of claim 4, further comprising a series of fixation members arranged around the hemispherical section in an implanted position.

6. The acetabular cup of claim 1 wherein the first and second porous metal layers both define preformed passages adapted to accept a fastener therethrough.