Patent ID: 8444676

Claim:
A spinal anchor assembly for securing a spinal fixation element, comprising: an anchor element adapted for attachment to bone and defining a central longitudinal axis, the anchor element having an opening for receiving the spinal fixation element, side walls on opposed sides of the opening, and a plurality of inferior surfaces defined on the side walls; and a closure element for closing the opening in the anchor element and applying pressure to the spinal fixation element to capture the spinal fixation element within the opening, the closure element including a closure body and a plurality of closure flange segments extending from the closure body in a direction that is generally transverse to the central longitudinal axis of the anchor element when the closure element is placed in the opening, the closure element being configured to be twisted from an open position in which the closure flange segments and the inferior surfaces are rotationally offset to a closed position in which the closure flange segments and inferior surfaces are interlocked; and a locking element provided on the closure element and the anchor element, the locking element being configured so that when the closure element is rotated from the open position to the closed position, the locking element engages to deter the closure element from twisting back to the open position.