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...http://www.google.fr/patents/US5667508?utm_source=gb-gplus-shareBrevet US5667508 - Unitary locking cap for use with a pedicle screw
