A fastener, for example a bone screw, is sized to pass through a hole of an implant, for example a bone plate, the fastener having a shaft or anchor portion engageable with body tissue, and a head portion. A locking cap secures to the bone plate and covers the head to block the head and inhibit screw back out. Alternatively or additionally, a locking disc located in the plate hole resiliently deflects downward to allow screw insertion, but is blocked to limit or prevent upward deflection so that screw back out is inhibited.
