HIP JOINT PROSTHESES

• US 3,829,904 A
• Filed: 09/22/1972
• Issued: 08/20/1974
• Est. Priority Date: 09/24/1971
• Status: Expired due to Term

• Current Assignee: Alan John Clive Lee, Robin Sydney Mackwood Ling
• Original Assignee: Alan John Clive Lee, Robin Sydney Mackwood Ling
• Inventors: Ling, Robin Sydney Mackwood, Lee, Alan John Clive
• Primary Examiner(s): Gaudet, Richard A.
• Assistant Examiner(s): Frinks, Ronald L.
• Application Number:
  US05/291,160
• Time in Patent Office: 697 Days
• Field of Search: 128/92CA,92C,92R,92BC 3/1
• US Class Current: 623/22.39
• CPC Class Codes: A61B 17/025 Joint distractors
• CPC Class Codes: A61B 17/2833 Locking means
• CPC Class Codes: A61B 90/39 Markers, e.g. radio-opaque or breast lesions markers
• CPC Class Codes: A61F 2/30724 Spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/367 Proximal or metaphyseal parts of shafts trochanteric devices connected to said proximal parts A61F2/30739
• CPC Class Codes: A61F 2/3676 Distal or diaphyseal parts of shafts
• CPC Class Codes: A61F 2002/3008 radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30154 square
• CPC Class Codes: A61F 2002/30571 Leaf springs
• CPC Class Codes: A61F 2002/30617 Visible markings for adjusting, locating or measuring
• CPC Class Codes: A61F 2002/3071 Identification means; Administration of patients
• CPC Class Codes: A61F 2002/3082 Grooves
• 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 2002/4631 the prosthesis being specially adapted for being cemented
• CPC Class Codes: A61F 2230/0019 rectangular
• CPC Class Codes: A61F 2230/0021 square
• CPC Class Codes: A61F 2250/0089 coded with symbols, e.g. dots, numbers, letters, words
• CPC Class Codes: A61F 2250/0097 : Visible markings, e.g. indicia
• CPC Class Codes: A61F 2250/0098 : radio-opaque, e.g. radio-opaque markers

Abstract

A prosthetic hip cup is provided which is generally similar to the usual basically hemispherical form except that: the inner and outer surfaces have their spherical centres displaced, rather than coincident, to provide a greater wall thickness at the bottom of the cup compared to the side; and the axes of symmetry of the inner and outer surfaces are mutually angled to off-set the thickest part of the cup relative to the axis of the outer surface. This overall eccentricity provides greatest thickness in the main load bearing region of the cup, without introducing any significant disadvantage. An associated femoral device is also provided which is again generally similar to the usual ball headed tapered stem form except that: the ball is connected to the stem through a necked part without introducing a flange; and the stem is tapered in at least two different transverse directions. The absence of a flange simplifies the associated sectioning requirements for the femur, and the multiple tapering of the stem promotes better extrusion of gap-filling cement.

Claims

1. A prosthetic acetabular device comprising a cup having an inner surface and an outer surface, which surfaces are of similar form including a substantially hemispherical major surface portion continuing into a crescent-shaped minor portion, said major surface portions being mutually eccentrically disposed by relative translation of their respective spherical centres and mutual angling of their respective radial axes of symmetry, and said crescent-shaped minor portions being disposed in mutually opposed manner and each being intersected in similar medial manner by the plane passing through said radial axes.

2. A device according to claim 1 wherein each of said inner and outer surfaces comprises a cylindrical minor surface portion located between the respective hemispherical and crescent-shaped surface portions as a smooth continuation of the first of these last-mentioned portions.

3. A device according to claim 1 wherein said outer surface is grooved by the provision of a plurality of first grooves of annular form disposed in transverse radial planes relative to said outer surface axis of symmetry, and a plurality of second grooves of part annular form disposed orthogonally relative to said first grooves to intercommunicate at least some of said first grooves.

4. A device according to claim 1 comprising a radio-opaque member of annular form connected around said cup in a plane substantially tangential to said inner surface at the closed end region thereof.

5. A device according to claim 1 in combination with a prosthetic femoral device comprising a substantially spherically shaped head part received in mutual bearing engagement with the inner surface of said cup and joined by a necked part to an elongate stem, the longitudinal direction of said head part and necked part being angled relative to that of said stem, said stem having noncircular cross-sectional shaping, and said stem being convergently tapered away from said necked part in at least two lateral directions and along a major longitudinal portion thereof.

6. A device according to claim 5 wherein said stem is of generally rectangular cross-sectional form with the corners of such form chamfered along a major longitudinal portion of said stem and to a progressively increasing depth therealong towards said necked portion.

7. A device according to claim 5 wherein said head part is off-set relative to said necked part in a direction away from that of the included angle of said necked part and said stem.

8. A device according to claim 5 wherein a major portion of said stem remote from said necked part is of substantially symmetrical form relative to a longitudinal axis through the former, and the remaining part of said stem has a generally chamfered surface remote from the included angle between said stem and necked part, which chamfered surface defines a visibly detectable boundary intersected by said longitudinal axis.

9. A device according to claim 5 wherein said stem is visibly marked to define a succession of predetermined discrete positions extending longitudinally therealong from a first position adjacent said necked part.

10. A device according to claim 5 in combination with a spacer device comprising an annular base member having at least three spring members extending from mutually spaced positions around said base member, said base member being engaged around and part way along said stem, and each of said spring members extending in directions hAving an outward radial component and a common axial component relative to said base member.

11. A prosthetic acetabular device comprising:

a cup having an inner surface and an outer surface;

said inner surface including a substantially hemispherical major surface portion continuing smoothly into a substantially cylindrical minor surface portion, which latter portion itself continues smoothly into a crescent-shaped further minor surface portion; and

said inner and outer surfaces having an eccentric relationship to define a varying thickness for said cup, with a region of maximum thickness being intersected by the radial axis of symmetry of said major surface portion.