Non-dislocatable low-wear hip prosthesis

• US 6,042,612 A
• Filed: 10/07/1998
• Issued: 03/28/2000
• Est. Priority Date: 02/02/1996
• Status: Expired due to Fees

• Current Assignee: Gilles Voydeville
• Original Assignee: Gilles Voydeville
• Inventors: Voydeville, Gilles
• Primary Examiner(s): SNOW, BRUCE EDWARD
• Application Number:
  US09/117,680
• Time in Patent Office: 538 Days
• Field of Search: 623/181, 623/19, 623/22, 623/23
• US Class Current: 623/23.15
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30448 using adhesives
• CPC Class Codes: A61F 2002/30451 soldered or brazed or welded
• CPC Class Codes: A61F 2002/30685 Means for reducing or preventing the generation of wear particulates
• CPC Class Codes: A61F 2002/3208 Bipolar or multipolar joints, e.g. having a femoral head articulating within an intermediate acetabular shell whilst said shell articulates within the natural acetabular socket or within an artificial outer shell
• CPC Class Codes: A61F 2002/3233 having anti-luxation means for preventing complete dislocation of the femoral head from the acetabular cup
• CPC Class Codes: A61F 2002/3241 having a ring, e.g. for locking the femoral head into the acetabular cup
• CPC Class Codes: A61F 2002/3443 with an anti-luxation elevated rim portion, e.g. on the inner shell
• CPC Class Codes: A61F 2002/345 the inner and outer (hemi)spherical surfaces of a shell, e.g. an intermediate shell, having distinct centres of rotation, both located on the centre line of the shell
• CPC Class Codes: A61F 2002/3493 Spherical shell significantly greater than a hemisphere, e.g. extending over more than 200 degrees
• CPC Class Codes: A61F 2002/3611 Heads or epiphyseal parts of femur
• CPC Class Codes: A61F 2002/365 Connections of heads to necks
• CPC Class Codes: A61F 2220/0041 using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2220/005 using adhesives
• CPC Class Codes: A61F 2220/0058 soldered or brazed or welded
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00179 Ceramics or ceramic-like structures

Abstract

This hip prosthesis includes a femoral stem (3), a spherical head (6) designed to fit over a neck (5) of the femoral stem, and a metal socket (1) in which the head can articulate; a cup (7) is inserted between the head (6) and the socket, the head and the cup being made of ceramic or similar material having a low coefficient of friction, the head being articulated on the cup; the cup itself is articulated in a plastic socket (8) fixed in the metal socket (1). This prosthesis thus comprises a double articulation, on the one hand between its head (6) and the cup (7), and on the other hand between the cup (7) and the polyethylene socket (8), the first ceramic-ceramic articulation being the one principally stressed. For this reason, the wear of the polyethylene socket (8) produces extremely little debris, which considerably reduces the risks of separation and very substantially prolongs the total lifetime of the prosthesis. This prosthesis has low-wear properties.

Claims

1. Hip prosthesis comprising:

a femoral stem having a first end adapted to be implanted in a femur, and a neck at an opposite second end;

a femoral head comprising a substantially spherical body having an outer surface, and a bore structured and arranged to fit over the neck;

a cup having an outer surface, and an inner surface structured and arranged to fit over the outer surface of the head;

the head being pivotable relative to the cup;

said head and said cup being made of a material having a low coefficient of friction and selected from the group consisting of a ceramic and a metal compound with ion implantation;

a metal socket having an inner surface, and an outer surface intended to be anchored in an acetabular cavity;

a plastic socket having an outer surface fixed to the inner surface of the metal socket, and an inner surface structured and arranged to fit over the outer surface of the cup;

the cup being pivotable relative to the plastic socket; and

said cup being structured and arranged for non-removable attachment to said head.

2. Prosthesis according to claim 1, wherein the cup and the head are made of a ceramic material.

3. Prosthesis according to claim 1, wherein the cup is made up of a substantially hemispherical part and of a ring formed by a portion of a sphere, fixed to the hemispherical part in order to prevent the hemispherical part from separating from the head.

4. Prosthesis according to claim 3, wherein the ring is fixed to the hemispherical part by one of adhesive bonding and soldering.

5. Prosthesis according to claim 3, wherein the ring constitutes a portion of about one quarter of a sphere.

6. Prosthesis according to claim 3, wherein the ring constitutes a portion of about one sixth of a sphere.

7. Prosthesis according to claim 3, wherein the ring constitutes a portion of about one eighth of a sphere.

8. Prosthesis according to claim 1, wherein the plastic socket is made of polyethylene, and the metal socket is made of titanium.