a compression screw assembly for applying compression to a fractured bone includes a lag screw , a compression plate including a hollow barrel member adapted to receive the lag screw in at least one fixed orientation , a wrench assembly adapted to releasably engage the lag screw in axial alignment therewith , and apparatus having surface contours complimentary with the outer surface of the lag screw and inner surface of the barrel member for being optionally insertable into the barrel member to prevent axial rotation of the lag screw with respect to the barrel member .