Dual modulus hip stem

Patent metadata

Field	Value
Publication number	US-9132013-B2
Application number	US-201314132917-A
Country	US
Kind code	B2
Filing date	Dec 18, 2013
Priority date	Jun 18, 2012
Publication date	Sep 15, 2015
Grant date	Sep 15, 2015

Abstract

An orthopaedic prosthesis for use in a hip replacement surgery. The orthopaedic prosthesis includes a metallic foam shell and a metallic core. The metallic core includes a neck configured to receive a femoral head component and a stem extending through the metallic foam shell.

First claim

The invention claimed is:

1. An orthopaedic prosthesis, comprising:
a metallic foam shell including a sheath, and
a metallic core including (i) a neck positioned proximal of the sheath, the neck being configured to receive a femoral head component, (ii) a first core segment positioned in the sheath, and (iii) a second core segment positioned distal of the sheath,
wherein the metallic foam shell further includes a cover layer extending distally from the sheath, the cover layer engaging only a lateral surface of the second core segment,
wherein when the orthopaedic prosthesis is viewed in a transverse plane extending through the cover layer of the metallic foam shell, (i) the cover layer defines a first cross-sectional area, (ii) the cover layer and the second core segment define a second cross-sectional area, and (iii) a ratio of the first cross-sectional area to the second cross-sectional area is greater than 0.30.

2. The orthopaedic prosthesis of claim 1 , wherein the ratio of the first cross-sectional area to the second cross-sectional area is between 0.35 and 0.47.

3. The orthopaedic prosthesis of claim 1 , wherein the ratio of the first cross-sectional area to the second cross-sectional area is less than 0.56.

4. The orthopaedic prosthesis of claim 1 , wherein when the orthopaedic prosthesis is viewed in a second transverse plane extending through the sheath of the metallic foam shell,
the sheath defines a third cross-sectional area,
the sheath and the first core segment define a fourth cross-sectional area, and
a ratio of the third cross-sectional area to the fourth cross-sectional area is greater than 0.38.

5. The orthopaedic prosthesis of claim 4 , wherein the ratio of the third cross-sectional area to the fourth cross-sectional area is between 0.46 and 0.54.

6. The orthopaedic prosthesis of claim 4 , wherein the ratio of the third cross-sectional area to the fourth cross-sectional area is less than 0.70.

7. The orthopaedic prosthesis of claim 4 , wherein the ratio of the third cross-sectional area to the fourth cross-sectional area is greater than the ratio of the first cross-sectional area to the second cross-sectional area.

8. The orthopaedic prosthesis of claim 4 , wherein:
the first core segment of the metallic core has a medial surface and a lateral surface positioned opposite the medial surface of the first core segment,
the sheath has a medial surface and a lateral surface positioned opposite the medial surface of the sheath, and
when the orthopaedic prosthesis is viewed in the second transverse plane, a first thickness is defined between a lateral-most point of the lateral surface of the sheath and a lateral-most point of the lateral surface of the first core segment, (ii) a second thickness is defined between a medial-most point of the medial surface of the sheath and a medial-most point of the medial surface of the first core segment, and (iii) a ratio of the second thickness to the first thickness is greater than 0.14.

9. The orthopaedic prosthesis of claim 1 , wherein:
the cover layer of the metallic foam shell extends distally from a proximal end attached to the sheath, and
the transverse plane extends through the proximal end of the cover layer, and when the orthopaedic prosthesis is viewed in the transverse plane: (i) the cover layer has a first thickness, (ii) the second core segment has a second thickness, and (iii) a ratio of the first thickness to the second thickness is greater than 0.46.

10. The orthopaedic prosthesis of claim 9 , wherein the first thickness is greater than three millimeters.

11. The orthopaedic prosthesis of claim 4 , wherein when the orthopaedic prosthesis is viewed in the second transverse plane, a medial surface of the first core segment is convex and a lateral surface of the first core segment is convex.

12. The orthopaedic prosthesis of claim 10 , wherein when the orthopaedic prosthesis is viewed in the second transverse plane, the medial surface of the first core segment is defined by a first radius, and the lateral surface of the first core segment is defined by a second radius that is greater than the first radius.

13. The orthopaedic prosthesis of claim 1 , wherein the sheath and the cover layer of the metallic foam shell have a first elastic modulus and the first core segment and the second core segment of the metallic core have a second elastic modulus, the first elastic modulus being approximately one-twentieth of the second elastic modulus.

14. An orthopaedic prosthesis, comprising:
an elongated femoral stem component having a longitudinal axis, the stem component comprising:
a metallic foam shell including a sheath, and
a metallic core including (i) a neck positioned proximal of the sheath, the neck being configured to receive a femoral head component, (ii) a first core segment positioned in the sheath, and (iii) a second core segment positioned distal of the sheath,
wherein (i) the metallic foam shell further includes a cover layer extending distally from the sheath, the cover layer engaging only a lateral surface of the second core segment and defining a first cross-sectional area at a first point on the longitudinal axis, (ii) the cover layer and the second core segment define a second cross-sectional area at the first point, and (iii) a ratio of the first cross-sectional area to the second cross-sectional area is greater than 0.30.

15. The orthopaedic prosthesis of claim 14 , wherein (i) the sheath defines a third cross-sectional area at a second point on the longitudinal axis, (ii) the sheath and the first core segment defines a fourth cross-sectional area at the second point, and (iii) a ratio of the third cross-sectional area to the fourth cross-sectional area is greater than 0.38.

16. An orthopaedic prosthesis for a patient, comprising:
an elongated femoral stem component having a longitudinal axis, the stem component comprising:
a metallic foam shell having a first elastic modulus, and
a metallic core including a neck positioned proximal of the shell and a body that extends through the shell, the core having a second elastic modulus greater than the first elastic modulus,
wherein (i) the metallic foam shell defines a first cross-sectional area at a first point on the longitudinal axis, (ii) the stem component defines a second cross-sectional area at the first point, and (iii) a ratio of the first cross-sectional area to the second cross-sectional area is greater than 0.38,
wherein (i) the metallic foam shell defines a third cross-sectional area at a second point on the longitudinal axis, the second point being distal of the first point, (ii) the stem component defines a fourth cross-sectional area at the second point, and (iii) a ratio of the third cross-sectional area to the fourth cross-sectional area is greater than the ratio of the first cross-sectional area to the second cross-sectional area,
wherein (i) the metallic foam shell defines a fifth cross-sectional area at a third point on the longitudinal axis, the third point being distal of the second point, (ii) the stem component defines a sixth cross-sectional area at the third point, and (iii) a ratio of the fifth cross-sectional area to the sixth cross-sectional area is less than the ratio of the third cross-sectional area to the fourth cross-sectional area,
wherein the metallic foam shell includes a cover layer attached to only a lateral surface of the metallic core at the third point on the longitudinal axis.

17. The orthopaedic prosthesis of claim 16 , wherein the ratio of the fifth cross-sectional area to the sixth cross-secti

Assignees

• Depuy Synthes Products Inc

Inventors

• Armacost John M
• Keefer Ryan C
• Mcanelly Jeffrey A

Classifications

• A61F2/3662 Primary

  Femoral shafts · CPC title

• A61F2002/30968

  Sintering · CPC title

• A61F2310/00029

  Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium · CPC title

• A61F2310/00413

  Coating made of cobalt or of Co-based alloys · CPC title

• Y10T29/49826

  Assembling or joining · CPC title