A bone fixation apparatus (10) is disclosed which includes an elongated plate member (12) with at least two pairs of circular openings (24, 26) and a series of circular openings (62) positioned along the plate member (12). The circular openings each form a cavity (30) with walls (31) extending between the upper and lower plate member surfaces (16, 18), the cavities having smaller diameter portions (32) at the plate member surfaces (16, 18) and a larger diameter portion (34) therebetween. The cavities are configured in the shape of two inverted cones (31a, 31b) with matching base circles (31c) for allowing angulation of an implanted bone screw (14). A plurality of bone screws (14) are provided, each having a threaded first end portion (36) and an ellipsoid-shaped enlarged second end portion (40). A locking member (48) is also provided which connects to the second end portion (40) of each bone screw (14) for expanding the second end portion (40) so as to grip the cavity wall (31) of the plate member (12).