An apparatus for treating a bone comprises an implant to be received within the bone, including a plurality of bores extending therethrough and a cavity formed therewithin, each of the bores being dimensioned to receive a bone fixation element and a plurality of inserts receivable in the cavity. Each insert includes an opening extending therethrough and configured to align with a corresponding bore. Each insert is movable between a resting configuration in which an opening width is smaller than a width of a bone fixation element inserted therethrough and a stressed configuration in which the opening width is expanded to a width greater than that of the bone fixation element in combination with a compression member movable into the cavity to apply a force moving the inserts from the resting configuration to the stressed configuration, withdrawal thereof reducing the force and permitting a return to the resting configuration.