Importance

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Abstract

An acetabular cup assembly 10 that uses the mating contour of its bearing component 20 and its shell component 30 to provide a reliable interlocking engagement to secure the bearing component to the shell component is disclosed. Bearing component 20 includes end surface 24 and a convex spherical surface 22, which extends beyond its lateral diametrical plane 23, making the shape of the bearing component slightly greater than a hemisphere. Shell component 30 includes a concave inner surface 36 defining an open cavity 37 for receiving bearing component 20. Concave shell surface 36 has a diametrical recess 40, and surface 36 is complimentary and approximately the same in contour and radial dimension to convex bearing surface 22. Concave shell surface 36 includes an annular portion 38, which extends beyond its lateral diametrical plane 39. Consequently, bearing component 30 can not be inserted directly into the shell cavity, because its lateral diameter is greater than the diameter at the mouth of the shell cavity. Recess 40 in concave shell surface 36 allows bearing component 20 to be inserted into shell cavity 37 in a sideways position. Once inserted in shell cavity 37 in a sideways position, bearing component 20 can be rotated back 90.degree. within the shell cavity so that convex bearing surface 22 is seated concentrically over concave shell surface 36. In this rotated position, annular portion 38 of concave shell surface 36 converges partially over bearing component 20 to secure the bearing component within shell cavity 37.

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First Claim