A retaining mechanism for use in affixing a stratum to bone is disclosed. The mechanism comprises a stratum and a retaining element. The retaining element comprises a central longitudinal axis, a stop end, a fastener end opposite that of the stop end, a first side, a second side, a first cut-out in the first side, a second cut-out in the second side, and a central cut-out. The stratum is configured to engage the retaining element such that when the retaining element is in a first position, the retaining element permits a fastener to be passed through a hole in the stratum, and when the retaining element is in a second position, the retaining element at least partially overlaps the hole so as to help prevent inadvertent backing out of the fastener after the fastener has been fully inserted into the hole.
