Abstract: Locking mechanisms and methods of fixation, such as the fixation of a fixation device like a bone screw and of a rod to the spine. The locking mechanism includes a body, a rod seat and a set screw. The rod seat is configured to separate into two pieces when the rod exerts force on the top portion of the washer and the set screw limits movement of the washer toward the bottom of the locking mechanism.

Abstract: A novel locking mechanism including a body and intermediate element and a method for locking the relative positions of a rod and a screw. The intermediate element is adapted to receive a rod and a head of a screw and is located between the rod and the head of the screw. The intermediate element has a non-circular shape such that at least one large non-contact area exists when the intermediate element is in contact with the head of the screw and the locking mechanism is fully engaged. The body is adapted to maintain the orientation of the non-circular intermediate element with respect to the body. The body also has at least one structure defining at least one distinct temporary stopping point for the intermediate element above the final locking position.

Abstract: Locking mechanisms and methods of fixation, such as the fixation of a fixation device like a bone screw and of a rod to the spine. The locking mechanism includes a body, a rod seat and a set screw. The rod seat is configured to separate into two pieces when the rod exerts force on the top portion of the washer and the set screw limits movement of the washer toward the bottom of the locking mechanism.