US Patent 7527641 Translational hinged door plate system

An assembly for use with a bone fastener includes a fixation device and a bone fastener retainer device. The fixation device has an opening configured to receive a bone fastener in an installed position in which an outer end portion of the bone fastener is located within the opening. The retainer device is receivable over the fixation device in a closed position extending over the location taken by the outer end portion of the bone fastener within the opening. Additionally, the fixation device and the retainer device together have first and second locking structures. The locking structures are configured to engage each other in an undeflected condition when the retainer device is in a partially closed position, and to snap into interlocked engagement with each other under an applied force that moves the retainer device from the partially closed position to the closed position.