Porous metal cup with cobalt bearing surface

• US 20070173948A1
• Filed: 02/22/2007
• Published: 07/26/2007
• 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: Meridew, Jason, Hershberger, Troy
• Granted Patent: US 8,066,778 B2
• Time in Patent Office: Days
• US Class Current: 623/22.240
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/4609 of acetabular cups
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30426 Bayonet coupling
• CPC Class Codes: A61F 2002/30471 connected by a hinged linkage mechanism, e.g. of the single-bar or multi-bar linkage type
• CPC Class Codes: A61F 2002/30601 telescopic
• CPC Class Codes: A61F 2002/30841 Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/3412 with pins or protrusions, e.g. non-sharp pins or protrusions projecting from a shell surface
• CPC Class Codes: A61F 2002/3441 the outer shell having an outer surface and an inner insert receiving cavity being angularly inclined with respect to the longitudinal axis of the outer surface
• CPC Class Codes: A61F 2002/4622 having the shape of a forceps or a clamp
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0091 connected by a hinged linkage mechanism, e.g. of the single-bar or multi-bar linkage type
• CPC Class Codes: A61F 2250/0024 made from both porous and non-porous parts, e.g. adjacent parts
• 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: A61F 2310/00407 Coating made of titanium or of Ti-based alloys
• CPC Class Codes: A61F 2310/00413 Coating made of cobalt or of Co-based alloys

Abstract

An acetabular cup assembly can include a cup portion and a bearing. The cup portion can include a porous metal outer layer having a first thickness and a solid titanium inner layer having a second thickness. A mating feature can be formed between the cup portion and the bearing. The bearing can be adapted to be selectively secured to the titanium inner layer. In one example, the bearing is formed of cobalt.

Claims

1. An acetabular cup assembly comprising:

a cup portion comprising;

a porous metal outer layer having a first thickness;

a solid inner layer having a second thickness; and

a mating portion formed from the porous metal outer layer and the solid inner layer; and

a bearing adapted to be selectively secured to the solid inner layer.

2. The acetabular cup assembly of claim 1 wherein a rim region of the cup portion is formed exclusively of solid titanium.

3. The acetabular cup assembly of claim 2 wherein the solid inner layer is integrally formed with the rim region.

4. The acetabular cup assembly of claim 2 wherein an inner surface of the rim region is tapered for receiving a tapered outer surface formed by the bearing.

5. The acetabular cup assembly of claim 3 wherein a transition from the rim region to the porous metal outer layer comprises:

a first annular pocket formed in the solid inner layer;

a second annular pocket formed in the porous metal outer layer;

a first annular lip extending around the solid inner layer and received within the second annular pocket; and

a second annular lip extending around the porous metal outer layer and received within the first annular pocket.

6. The acetabular cup assembly of claim 1 wherein the solid inner layer defines an inner mating surface having a first diameter and wherein the bearing defines an outer mating surface having a second diameter, wherein the second diameter is larger than the second diameter in an unassembled position.

7. The acetabular cup of claim 6 wherein the porous metal outer layer is adapted to be coupled to the solid inner layer during a heat treatment process.

8. The acetabular cup of claim 7 wherein the bearing is adapted to be cooled prior to assembly with the cup portion.

9. The acetabular cup of claim 1 wherein the cup portion defines passages formed therein.

10. The acetabular cup of claim 9, further comprising fasteners extending through at least some of the passages and securably extending into an acetabulum in an implanted position.

11. The acetabular cup of claim 1 wherein the cup portion defines an apical hole formed therein.

12. The acetabular cup of claim 1 wherein the second thickness is greater than the first thickness.

13. The acetabular cup of claim 12 wherein the second thickness is about 5 mm.

14. The acetabular cup of claim 1 wherein at least one annular lip is defined around the solid titanium inner layer and adapted to nest in at least one complementary pocket formed in the porous metal outer layer.

15. The acetabular cup of claim 1 wherein the bearing defines a first and second shoulder each extending substantially perpendicular relative to a longitudinal axis of the cup, the first and second shoulders having a tapered surface formed therebetween.

16. The acetabular cup of claim 1 wherein the bearing is formed of at least one of cobalt, ceramic and diamond.

18. The acetabular cup assembly of claim 16 wherein a transition from the rim region to the body comprises:

a first annular pocket formed in the solid metal portion;

a second annular pocket formed in the porous metal portion;

a first annular lip extending around the solid metal portion generally perpendicularly relative to a longitudinal axis of the cup portion and received within the second annular pocket; and

a second annular lip extending around the porous metal portion and received within the first annular pocket.

19. The acetabular cup assembly of claim 18 wherein the cup portion defines passages formed therein and adapted to accept fasteners in an implanted position.

17. An acetabular cup assembly comprising:

a cup portion having a body and a rim region, the cup portion including;

a porous metal portion formed at the body; and

a solid metal portion formed at the rim region; and

a bearing adapted to be selectively secured to the cup portion.

20. The acetabular cup of claim 17 wherein the bearing is formed of at least one of cobalt, ceramic and diamond.

21. An acetabular cup assembly comprising:

a cup portion having a body and a rim region, the cup portion comprising;

a porous metal portion formed at the body; and

a solid metal portion formed at the rim region and including a tapered mating surface formed around an inner surface; and

a bearing defining a complementary tapered mating surface formed around an outer surface, the bearing adapted to be selectively secured to the cup portion.

22. The acetabular cup assembly of claim 21 wherein a transition from the rim region to the body comprises:

a first annular pocket formed in the solid metal portion;

a second annular pocket formed in the porous metal portion;

a first annular lip extending around the solid metal portion and received within the second annular pocket; and

a second annular lip extending around the porous metal portion and received within the first annular pocket.

23. The acetabular cup assembly of claim 22 wherein the cup portion defines passages formed therein and adapted to accept fasteners in an implanted position.

24. The acetabular cup of claim 21 wherein the bearing is formed of at least one of cobalt, ceramic and diamond.