Endoprosthetic bone joint devices
AssigneeBritish Technology Group Limited
InventorJohn Christian Tracey Church
Life of this patent
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Abstract
An endoprosthetic acetabular component of overall cup form is improved by the provision of an outer part (100; 300; 500) for securement to bone and a plurality of inner parts (200; 400; 600) individually selectively interconnectable with the outer part in like manner but providing a dished articulating surface (203; 403; 603) in respectively different predetermined positions varying in depth and/or inclination. The interconnection is preferably rotatably adjustable relative to the cup mouth, suitably by the provision of mutually complementary indented/detented surface formations (104,202; 304,402; 505,607) on the parts. The outer part may also be selectable from a range adapted to respectively different manners of securement to bone.
Claims1
A system for forming a socket component for use in a ball-and-socket bone joint prosthesis, said system comprising:
- a plurality of bearing elements each having an articulation surface for receiving a ball;
- a fixation member adapted for securement to a bone and having a cavity for receiving any selected one of said bearing elements, said cavity having an opening defining a plane through which said one bearing element enters the cavity;
- and
- means for connecting said one bearing element to said fixation member in any one of a plurality of selectable orientations after such member has been attached to said bone, said plurality of orientations being mutually angularly displaced about an axis which is perpendicular to said plane and passes through said opening;
- said connecting means comprising a set of tapped bores located about the cavity of the fixation member and at least one hole in a rim of each bearing element overlying the tapped bores, whereby screws placed through the holes and extending into the tapped bores enables placement of the bearing element in the cavity of the fixation member in any one of the said selectable orientations;
- said articulation surface of at least a first one of said bearing elements being non-uniform about said axis when connected in said fixation member to provide a varying restraint against dislocation of said ball dependent on the direction of articulation;
- and
- said articulation surface of at least a second one of said bearing elements being uniform about said axis when connected in said fixation member to provide a uniform restraint against dislocation of said ball.
Dependencies are inferred from the claim text.