Aspheric hip bearing couple
AssigneeDePuy Synthes Products, Inc.
InventorCraig N. Ernsberger
Life of this patent
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Abstract
A joint prosthesis device comprises a head configured to fit within a cup. The cup includes a concave cup surface defined by at least one radius of curvature RC. The head includes a convex head surface defined by at least one radius of curvature RH. The convex head surface is configured to engage the concave cup surface. The convex head surface provides an articulation zone where the head surface engages the cup surface. RC differs from RH in the articulation zone by a first amount. The convex head surface also provide a peripheral zone outside of the articulation zone. RC differs from RH in the peripheral zone by a second amount that is greater than the first amount. The peripheral zone generally extends over an area subtended by a minimum angle having a vertex at a center of the head.
Claims20
A prosthetic device comprising:
- a cup including a concave cup surface, the concave cup surface defined by at least one radius of curvature RC;
- a head configured to fit within the cup, the head including a convex head surface configured to engage the concave cup surface, the convex head surface defined by at least one radius of curvature RH;
- an articulation zone provided upon the convex head surface, the head surface configured to engage the cup surface in the articulation zone, wherein RC differs from RH in the articulation zone by a first amount that is no greater than forty microns;
- and
- a peripheral zone provided on the convex head surface outside of the articulation zone, wherein RC differs from RH in the peripheral zone by a second amount that is greater than the first amount but is no greater than fifty microns, and wherein the peripheral zone extends over an area subtended by a peripheral zone angle of at least 10°, the peripheral zone angle having a vertex at a center of the head.
A prosthetic device comprising:
- a cup including a concave cup surface, the concave cup surface defined by at least one radius of curvature RC;
- a head configured to fit within the cup, the head including a convex head surface configured to engage the concave cup surface, the convex head surface defined by at least one radius of curvature RH;
- an articulation zone provided on the convex head surface, the convex head surface configured to engage the concave cup surface in the articulation zone, wherein RC differs from RH in the articulation zone by a first radial clearance, wherein the first radial clearance is no greater than fifty microns;
- a peripheral zone provided on the convex head surface outside of the articulation zone, wherein RC differs from RH in the peripheral zone by a second radial clearance that is greater than the first radial clearance;
- and
- wherein the first radial clearance gradually increases in the articulation zone from a lesser radial clearance near a pole of the head to a greater radial clearance near the peripheral zone.
A prosthetic device comprising:
- a cup including a concave cup surface, the concave cup surface defined by at least one radius of curvature RC;
- a head configured to fit within the cup, the head including a convex head surface configured to engage the concave cup surface, the convex head surface defined by at least one radius of curvature RH;
- wherein the convex head surface provides an articulation zone where the head surface engages the cup surface, wherein RC differs from RH in the articulation zone by a first amount that is less than fifty microns, and wherein the articulation zone extends over a first area subtended by a first angle between 85° and 105°, the first angle having a vertex at a center of the head;
- wherein the convex head surface provides a transition zone adjacent the articulation zone, wherein RC differs from RH in the transition zone by a second amount that is greater than the first amount but is no greater than fifty microns, and wherein the transition zone extends over an area subtended by a second angle of at least 10°, the second angle having a vertex at the center of the head;
- and
- wherein the convex head surface provides an equatorial zone adjacent the transition zone such that the transition zone lies between the articulation zone and the equatorial zone, wherein RC differs from RH in the equatorial zone by a third amount that is greater than the first amount and the second amount but is no greater than fifty microns, and wherein the equatorial zone extends over an area subtended by a third angle of at least 10°, the third angle having a vertex at the center of the head.
Dependencies are inferred from the claim text.