A bone fixation apparatus may include a bone fixation plate having a fixation hole and a fastener shaft received in the fixation hole. The fastener shaft may include a first portion having an outer surface defining a first cam and a second bone-engaging portion. An annular member may be received in the fixation hole and may include an inner surface defining a second cam for cooperating with the first cam to selectively move the annular member in a radial direction between an unexpanded position permitting movement of the fastener shaft and annular member relative to the fixation hole and an expanded position restricting movement of the fastener shaft and annular member relative to the fixation hole. The annular member may be moved between the expanded position and the unexpanded position by rotation of the annular member relative to the fastener shaft following insertion of the fastener shaft into a bone.
