An apparatus (10) is provided for implantation into a bone (12) in a patients spine or pelvis. The apparatus (10), when implanted, is resistant to toggling in the bone (12) and to being pulled from the bone. The apparatus (10) comprises a platform (24) having a first surface (38) for facing the bone (12) in a patients spine or pelvis. The platform (24) includes structure (32, 34, 36) for connection to a spinal fixation implant (100). The apparatus (10) further comprises helical spikes (50, 52) for embedding into the bone (12) upon rotation of the platform (24). The helical spikes (50, 52) project tangentially from the platform (24) and extend around a longitudinal axis (22). The helical spikes (52, 52) have a tip portion (58) at a distal end (62) which penetrates into the bone (12) as the platform (24) is rotated. The helical spikes (50, 52) further have a connecting portion (54) at a proximal end (58) connected to the platform (24) and an intermediate portion (56) extending between the connecting portion (54) and the tip portion (58).
