An orthopedic device has a configuration that employs a scalloped profile that defines internal scalloped edges having troughs and crests that extend substantially along the outer edge of a head of the device. The troughs and crests interface with a series of troughs and crests around the openings in the device. Each of the openings includes an outwardly extending slot that permits the opening to expand and contract outward as the head of the anchor is rotated. This enables an anti-backout feature that prevents or substantially inhibits undesired rotation and backout.
