Occipital plate and rod system

摘要

The present invention has a plate and rod assembly for implantation in the cervical region of the spine which includes an occipital plate having an angled anchor bridging area that is attached to the lower posterior curve of the skull. On either side the bridging area is connected to offset legs which join flanged areas that include tethered rod anchors having rod-receiving channels. Specifically, the flanged areas have a high friction surface, which is preferably knurled, to bite into the surface of the rod that is received in the channels. These flanges include undercut slots that capture the side plates integral to the open U-shaped members including the rod-receiving channels. The side plates extend longer in the direction of the longitudinal axis of the rod when it is in the channel. These side plates can thus be lowered into the slot and rotated by 90 degrees to capture the channels in the flanges since the undercut slots are not as wide as they are long. The channels are closed by a capnut which has a bottom annular flange that also helps to lock the rod in place. The angle of the rod-receiving flanges relative to the plate bridging area allows the rods to be positioned close to the cervical vertebrae so that they can also be attached to the cervical vertebrae using vertebral anchors. The capnut is self-aligning as it includes an internal projection that cooperates with the internal recess of the rod-receiving channel members in the direction of the longitudinal axis of the attachment screw. Further, the capnut includes a visual alignment cue that helps to inhibit cross threading by indicating the proper side for starting the capnut on the threads of the channel. Three debossed dots show the alignment relative to a similarly placed set of dots on the proper side of the rod-receiving channel.