on insertion and rotation of a screw body through lumen 2 the rotation can exert a rotation force on body 1 engagement of wings 10 11 and flanges 13 14 with surrounding bone will stabilize the anchor position to further stabilize the anchor assembly during its implantation anchor head 15 may be further provided with a pair of opposing recesses 21 and 22 as shown in fig8 b recesses 21 22 provide a structure for engagement of a retaining tool such as a hemostat to hold the anchor assembly in place as it is being deployed following insertion of a bone screw into the anchor body the helical turns of the screw face will engage surrounding bone stabilizing the anchor and screw in place within the bone the inner diameter of lumen 2 is therefore adapted to allow for insertion of a screw through lumen 2 whereby the helical turns of the screw face will protrude from vertical slots 5 6 to engage with surrounding bone it will be appreciated that the outer surfaces along body 1 wings 10 11 and flanges 13 14 can be treated to be especially well suited to a particular application e g fixation or stabilization of bone at various levels of the spine for example the surfaces may be smooth sanded or micro abrasive blasted to.