Importance

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Abstract

A unitary locking cap mechanism, which is used with pedicle screws and other orthopaedic implant devices which couple bones to rods, includes rim and post portions which are rotationally freely coupled to one another to permit independent motion relative to one another. The rim element has a cylindrical body with an open end and a closed end; the closed end alternatively having a concentric hole defined by an inwardly directed flange. In one embodiment, the flange includes a series of slots, dividing into a plurality of wedge-shaped pie sections. In another embodiment, the sidewall of the cylindrical portion of the rim includes an annular recess. The post is a cylindrical shaft having surface elements at one end which provide for mutual engagement with the rim. These surface elements may be deflecting arms which seat into the annular recess of the rim, or an annular recess in the shaft into which the wedge-shaped pie sections of the flange portion may be resiliently snapped into. In an alternative embodiment, the shaft and the rim are coupled together through the concentric hole by a retaining ring which is placed around the shaft, in an annular recess therein, after the insertion of the shaft through the hole. Each embodiment are alternatively designed such that the post or the inner surface of the rim portions are threaded so that it can mate with a threading on the inner or outer upwardly extending, U-shaped channel forming, members of the heads of the pedicle screws.

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First Claim