A bone plate system includes a plate member, a disk, and a cover member. The plate member having a through-hole extending through top and bottom sides of the plate member. The disk is receivable in the through-hole to be rotatably supported in the plate member about an axis of rotation extending from the top side to the bottom side. The disk includes a slot configured to receive a bone anchor therethrough. The slot has a non-circular shape when viewed along the axis of rotation to allow a guided displacement of the bone plate in a plane perpendicular to the axis of rotation. The cover member is configured to cover the bone anchor and the disk when the disk is received in the through-hole of the plate member.
