Acetabular cup having polyaxial locking screws
First Claim
1. An acetabular cup having polyaxial locking anchoring screws for securing said cup within a recess of surrounding bone, comprising:
- an acetabular cup having a plurality of through holes having a constant linear taper;
a corresponding plurality of coupling elements, each of said coupling elements being insertable into a corresponding one of said through holes; and
a plurality of bone screws, each of said bone screws having a semi-spherical head portion and a shaft, said shaft portion being insertable through the corresponding through hole and into the surrounding bone, and said semi-spherical head portion being rotationally freely mounted in the coupling element prior to insertion and such that the shaft of the bone screw and the coupling element may be inserted into a corresponding through hole and said shaft of the bone screw may be inserted into the surrounding bone at a selected angle within a predetermined range of angles relative to the acetabular cup and thereby locking said coupling element and said semi-spherical head within said hole of said acetabular cup at said selected angle.
3 Assignments
0 Petitions
Accused Products
Abstract
The present invention is an acetabular cup having polyaxial locking screws for anchoring the cup in the desired bone site. The assembly includes an acetabular cup having axially tapered holes, into which holes coupling elements and bone screws may be inserted. The coupling elements each have an axial taper which matches the taper of the corresponding hole, and an interior semi-spherical concave surface in which the semi-spherical head of a corresponding bone screw may be polyaxially mounted. The bone screws are inserted through the holes until the coupling elements fully seat in the respective holes, thereby locking the screws in place and the coupling elements in the holes. In a preferred embodiment, the upper part of the holes further include annularly recessed channels in each of which a snap-ring is disposed. During the insertion of the bone screw, the advancing of the coupling element into the hole causes the snap-ring to expand. Once the coupling element is fully seated in the hole, the snap-ring contracts to its undeflected position and prevents the coupling element and screw from backing out of the hole in the event of loosening.
338 Citations
9 Claims
-
1. An acetabular cup having polyaxial locking anchoring screws for securing said cup within a recess of surrounding bone, comprising:
-
an acetabular cup having a plurality of through holes having a constant linear taper; a corresponding plurality of coupling elements, each of said coupling elements being insertable into a corresponding one of said through holes; and a plurality of bone screws, each of said bone screws having a semi-spherical head portion and a shaft, said shaft portion being insertable through the corresponding through hole and into the surrounding bone, and said semi-spherical head portion being rotationally freely mounted in the coupling element prior to insertion and such that the shaft of the bone screw and the coupling element may be inserted into a corresponding through hole and said shaft of the bone screw may be inserted into the surrounding bone at a selected angle within a predetermined range of angles relative to the acetabular cup and thereby locking said coupling element and said semi-spherical head within said hole of said acetabular cup at said selected angle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. An acetabular cup having anchoring screws and collars for polyaxially locking said screws within axially tapered holes through said acetabular cup, comprising:
-
an acetabular cup having a plurality of holes therethrough said holes having a constant linear taper; a plurality of bone screws, each having a threaded shaft and a semi-spherical head; a corresponding plurality of coupling elements, each having an axially tapered exterior surface, said taper corresponding to the taper of the holes in said acetabular cup; each of said coupling elements further including an interior semi-spherical volume for polyaxially retaining the semi-spherical head of said corresponding bone screw; and each of said coupling elements further including at least one axial slot formed therein, which at least one slot provides for an expansion and contraction of the interior semi-spherical volume upon the application of a radial force on the exterior surface thereof; whereby said shaft of the bone screw may be inserted through said hole and into the bone at a selected angle within a predetermined range of angles including non-perpendicular angles relative to the tapered hole, such that upon complete insertion, the coupling element and the semi-spherical head therein are drawn into the hole, the tapered inner surface of the hole applying an inwardly directed radial force to the coupling element which is sufficient to lock the coupling element within the tapered hole, and to lock the semi-spherical head of the screw in the semi-spherical interior volume of the coupling element.
-
Specification