Abstract: A collet for a spinal rod bone screw assembly is configured to provide an interference fit with the top or head of a polyaxial bone screw in order to aid in locking orientation of a polyaxial bone screw head relative to the polyaxial bone screw. An increase in spherical coverage created by the configuration of the collet increases the amount of surface contact with the polyaxial bone screw head. This allows for more controlled, uniform and secure orientation of the polyaxial head with respect to the bone screw during lock-up. A resilient, tapered base of the collet has a plurality of slots that allow the end of the collet to splay outwardly over and upon the head of the bone screw to create a snap or frictional interference fit between the collet and the polyaxial bone screw head when a spinal rod is fixed in the polyaxial bone screw head.

Abstract: A primer composition, particularly suitable for a highly plasticized polyolefin substrate, comprises a mixture of chlorinated polyolefin and rubberized epoxy resin.