Bone plate systems and anchor retainers are provided for use in surgical implants and bone repair. In a preferred form, the bone plate may include bores for receiving the bone anchors, and the bores may permit and define a path of translation or shifting of the bone anchors relative to the bone plate. The anchor retainers may be held in the bores to prevent back-out of the bone anchors. Once the anchor member is seated within the bone plate, the retainer may rest over a top surface of the anchor member so the anchor member is impeded from backing out of the bone plate. The retainer may expand or change shape to permit an anchor member to be driven through the retainer and may contract once an anchor member has been seated within the plate. In addition, a tool for insertion or extraction of the bone anchors is provided.