A retaining mechanism for use in affixing a stratum to bone is disclosed. The retaining mechanism comprises a stratum, a shoulder element and a retaining element. The stratum comprises a first surface, a second surface, and at least one hole extending between the first surface and the second surface, wherein the second surface is configured to engage at least a portion of the bone. The shoulder element is configured to engage the stratum and configured to at least partially overlap the at least one hole. The retaining element is configured to engage the stratum and configured to at least partially overlap the shoulder element such that the shoulder element helps prevent inadvertent backing out of a fastener after the fastener has been fully inserted into the at least one hole.
