Joint prosthesis

• US 3,922,726 A
• Filed: 08/20/1974
• Issued: 12/02/1975
• Est. Priority Date: 08/27/1973
• Status: Expired due to Term

• Current Assignee: Claudio Trentani, Sergio Sandrolini Cortesi
• Original Assignee: Claudio Trentani, Sergio Sandrolini Cortesi
• Inventors: Trentani, Claudio, Cortesi, Sergio Sandrolini
• Primary Examiner(s): Frinks, Ronald L.
• Application Number:
  US05/498,883
• Time in Patent Office: 469 Days
• Field of Search: 3/1,1.91,1.912,1.913 128/92C,92CA,92R
• US Class Current: 623/22.15
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2002/30065 thermoplastic, i.e. softening or fusing when heated, and hardening and becoming rigid again when cooled
• CPC Class Codes: A61F 2002/3008 radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61F 2002/30378 Spherically-shaped protrusion and recess
• CPC Class Codes: A61F 2002/30662 with rotation-limiting means
• 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 2002/345 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 2210/0071 thermoplastic
• 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 2250/0098 radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys

Abstract

A hip joint prosthesis which comprises a cup member for placement in the acetabulum and configurated externally after a substantially spherical surface and internally to form a cavity for snap insertion on the spheroidal head of a stem to which it articulated and which is positioned in medullar cavity of the thigh bone after removal of the thigh bone epiphysis. The pivot center of said spheroidal head of the stem within the cavity of said cup member is located between the center and the spherical outer surface of the cup.

Claims

1. Hip-joint prosthesis comprising a cup member for placement in an articulating relation in an acetabulum of the pelvis, said cup member having a continuously smooth outer spherical surface and an inner spherical cavity which communicates with the outside through an opening, a femoral insert including a stem for insertion into the femoral bone after removal of the epiphysis thereof and a spheroidal head engaging said spherical cavity through said opening and articulated therein, wherein according to the improvement said spherical cavity is eccentrically located with respect to the outer surface of the cup member so as to be displaced in a direction diametrically opposite to said opening.

2. Hip-joint prosthesis as defined in claim 1 wherein said opening has an inner frusto-conical surface that diverges in a direction outwardly from said cavity.

3. Hip-joint prosthesis as defined in claim 2 wherein at the connection area of said spheroidal head to the stem, said stem has a lesser cross-section dimension than that of said opening.

4. Hip-joint prosthesis as defined in claim 2 wherein said cup member has a rotation symmetry about an axis passing through the center of said opening and the centers of said outer surface and inner cavity, the center of said cavity being located on said axis between the outer surface and the center thereof.