Elliptic acetabular component for a hip prothesis

• US 6,059,833 A
• Filed: 09/18/1996
• Issued: 05/09/2000
• Est. Priority Date: 12/16/1993
• Status: Expired due to Term

• Current Assignee: Plus Endoprothetik AG
• Original Assignee: Endocare AG
• Inventors: Doets, Hendrik Cornelis
• Primary Examiner(s): Yu, Mickey
• Assistant Examiner(s): STEWART, ALVIN J
• Application Number:
  US08/652,568
• Time in Patent Office: 1,329 Days
• Field of Search: 623/22, 623/23
• US Class Current: 623/22.21
• 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 2002/30367 with additional means for preventing said rotation
• CPC Class Codes: A61F 2002/30403 Longitudinally-oriented cooperating ribs and grooves on mating lateral surfaces of a mainly longitudinal connection
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30538 for adjusting angular orientation
• CPC Class Codes: A61F 2002/3054 about a connection axis or implantation axis for selecting any one of a plurality of radial orientations between two modular parts, e.g. Morse taper connections, at discrete positions, angular positions or continuous positions
• CPC Class Codes: A61F 2002/30841 Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/3401 with radial apertures, e.g. radial bores for receiving fixation screws
• CPC Class Codes: A61F 2002/3403 Polar aperture
• CPC Class Codes: A61F 2002/3417 the outer shell having protrusions on meridian lines, e.g. equidistant fins or wings around the equatorial zone
• CPC Class Codes: A61F 2002/3443 with an anti-luxation elevated rim portion, e.g. on the inner shell
• CPC Class Codes: A61F 2002/3456 ellipsoidal or having a flattened polar region
• CPC Class Codes: A61F 2002/4629 connected to the endoprosthesis or implant via a threaded connection
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2250/0006 for adjusting angular orientation
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00796 Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

A hip cup for use as an acetabular component in a hip prosthesis including a shell part having a partially convex outer surface. The shell part is insertable in a cavity having an inner surface that is substantially defined by the outer surface of a segment of a sphere. The outer surface of the shell part substantially corresponds to the outer surface of a part of an ellipsoid and has an apex. During positioning of the shell part in the cavity, the shell part has a circumferential edge contacting the longitudinal edge of the cavity, with a space formed between the inner surface of the cavity and the apex of the shell part. A tool has an end releasably attachable to the shell part and a striking end. A handle on the tool permits positioning the tool and shell part to the cavity and striking the end to enact the shell in the part in a selected position.

Claims

1. A hip cup for use as an acetabular component in a hip prosthesis of a patient having a bone cavity including an inner surface configured as a segment of spherical surface and which includes a peripheral portion, said cup comprising an outer shell having a partially convex outer surface and a circumferential edge portion and having an apex and a central cross-section and forming one half of an ellipse with a short radius through the apex and a long radius at the peripheral portion, the outer shell being configured for insertion into the bone cavity,

said circumferential edge portion of the outer surface of the outer shell upon insertion into said cavity contacts said peripheral portion of the cavity and is configured to form a space between the inner surface of the cavity and the apex of the outer shell, said outer surface of the outer shell being defined by rotation of said ellipse about said short radius and having a cross section in a plane containing the long radius of the ellipse to form a half rotational ellipsoid,

the ratio between the length of the short radius between said apex and said long radius and the length of the long radius within the ellipse is approximately between 0.9 and 0.975.

2. The hip cup of claim 1, wherein the hip cup comprises means (18) projecting outwardly from the shell surface, said means providing for the rotationally fixed attachment of the outer shell (1) in said bone cavity.

3. The hip cup according to claim 1, wherein the outer surface (11) of the outer shell (1) is biocompatible and promotes osteo-integration over at least a portion of the outer surface.

4. The hip cup according to claim 3, wherein the body of the outer shell (1) selected from the group of titanium or a titanium-containing alloy.

5. The hip cup according to claim 3, wherein the outer surface (11) of the outer shell (1) is at least partly porous.

6. The hip cup according to claim 3, wherein the outer surface (11) of the outer shell (1) is provided with a coating containing a calcium phosphate compound.

7. The hip cup of claim 1 comprising an inner shell (2) fittingly insertable substantially within the outer shell (1), said inner shell (2) having an inner surface in the shape of a spherical shell.

8. The hip cup according to claim 7, wherein the inner shell (2) is a synthetic material.

9. The hip cup according to claim 7, wherein the inner shell and said outer shell include means to support the inner shell in the outer shell in a number of relative rotational positions.

10. The hip cup according to claim 7, wherein the inner shell comprises an antiluxation edge, said edge extending outside the outer shell.

11. The hip cup of claim 1, wherein the outer shell includes at least one opening having a fastening means for receiving a mounting tool.

12. The hip cup of claim 6, wherein said compound is a hydroxyapatite.

13. The hip cup of claim 8, wherein said synthetic material is polyethylene.