Howmedica Corp.

Jon I Klippel

Glen A Kashuba

Michael Michielli

J Mel Goldenberg

A prosthesis with an integral proximal spacer is described. The prosthesis has a base element with a textured surface to aid in adhesion to bone cement. The integral spacer has a generally tripod shape. A top circumferential portion at least partially surrounds the proximal end of the prosthesis, and three legs extend distally along the length of the prosthesis. Also disclosed is the process for making the prosthesis and spacer, which preferably involves injection molding of PMMA.

Prosthesis with integral proximal spacer

An acetabular cup for use as a prosthetic implant has an insert with a body including a central bore for receiving a positioning rod therein. A key element is formed on the bore and is adapted to align the positioning rod. The insert has a locating element formed on an outer surface of the body and also includes spring elements extending radially outwardly from the body. The acetabular cup has a generally hemispherical shell member coupled to the outer surface of the insert. The shell has an outer surface for engaging the acetabulum and an inner surface having a circumferential groove for receiving the spring elements. The spring elements may be deflected radially inwardly out of engagement with the groove for releasing the insert from the shell. The spring elements can be deflected by pushing a sleeve down the rod to make contact with and deflect the spring element. The shell has a plurality of apertures extending from its inner to its outer surface, which apertures are located in an asymmetrical pattern about the shell. The shell includes a recess on its open end for receiving the locating element on the insert to align the insert at a predetermined orientation with respect to the apertures in the shell. The engagement of the insert onto the shell and the engagement of the locating element in the recess aligns the key element on the central bore and, therefore, the positioning rod at a predetermined orientation with respect to the apertures in the shell.

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Basking Ridge, NJ, United States of America

Jon I Klippel