Spinal plate assemblies, methods of fabrication, and methods of use. Such assemblies comprises blocking structures assembled to spinal plates. The blocking structure comprises an elongate band which can be against structure of the plate. The band is mounted into a continuous or intermittent channel in the plate, and extends into an aperture in the plate. The band responds to side forces applied by interfering elements of bone fasteners driven through an aperture, by moving away from the interfering element, and returning to a blocking position over the interfering element after the interfering element has passed the band. Methods of fabrication include inserting the blocking structure, optionally longitudinally, into the channel. Methods of use include advancing bone screws through an aperture and past the band. The bone screw deflects the band as the screw passes, and the band moves to the blocking position when the screw has moved past the band.
