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Disclosed is a barb anchor, which may used, by way of example only, to be applied to a bone, and to receive a bolt or a screw. However, anchors designed to receive a bolt or a screw may unscrew as a result of loosening the screw or bolt they hold. It would be desirable to have an anchor that, when attempting unscrewing, will tend to resist unscrewing, so that when an unscrewing torque is being applied to it, will react by tending, or attempting, to screw deeper into a substrate to which it is anchored. Therefore, there currently exists a need in the industry for an anchor and associated method that tend to resist application of unscrewing torque applied thereto, by developing reaction forces whose equivalent force tends to be directed into the substrate to which the anchor is fastened. A barb anchor may have a barb anchor body which may releasably secure a screw or a bolt in a substrate. For illustrative purposes only, such substrates may include, but are not limited to, bone or osseous tissues (see http://en.wikipedia.org/wiki/Bone_tissue, http://en.wikipedia.org/wiki/Osseous_tissue. The barb anchor body comprises an apical end and a distal end. An axis of rotation R extends through the apical and distal ends, defining a screwing-in direction I thereabout. The barb anchor body may have a thread comprising at least two thread wraps. Each haing an apical flank, a distal flank, and a radial-outer flank extending therebetween. One of the at least two thread wraps comprises at least one self-tapping notch formed therein. The at least one self-tapping notch defines a forward tooth face having a forward normal Nf facing tangentially forwardly relative to the direction of rotation R. The forward normal Nf may be disposed at a self-tapping angle a to the axis of rotation R. The self-tapping angle α may be neutral, i.e., at a right-angle to the axis of rotation R, or may be positively-inclined relative to, the axis of rotation R, i.e., tilted towards the distal end of the barb anchor body. One of the at least two thread wraps may further comprise at least one reverse notch formed therein. The at least one reverse notch defines a reverse tooth face having a rearward normal Nr facing tangentially rearwardly relative to the direction of rotation R. The rearward normal Nr may be disposed at a reverse angle b to the axis of rotation R. The reverse angle β may be negatively-inclined relative to the axis of rotation R, i.e., tilted towards the distal end of the barb anchor body. Possibly, the at least one self-tapping notch may be disposed on a different thread wrap than the thread wrap on which the reverse notch is disposed. Further possibly, the at least one of the two thread wraps on which the at least one self-tapping notch is disposed may be hencetoforth called a self-tapping thread wrap, while the other of the at least two thread wraps on which the at least one reverse notch is disposed may be hencetoforth called a reverse thread wrap. The barb anchor may potentially be further provided with more than one self-tapping thread wrap and also further potentially with more than one reverse thread wrap. The reverse notch may be disposed on different thread wraps than the self-tapping notch. Further possibly, the reverse thread wraps may be disposed distally relative to the self-tapping thread wraps. Further potentially, the self-tapping notch may penetrate the barb anchor body. Also, further potentially, each self-tapping thread wrap may comprise more than at least one self-tapping notch. Similarly, each reverse thread wrap may comprise more than the at least one reverse notch. When the barb anchor body goes through osseointegration (see http://en.wikipedia.org/wiki/Osseointegration) the reverse thread wraps may be immersed in osseous tissue, with the reverse tooth face or faces bearing on the bone tissue. Thus, if, for example, a mechanical, unscrewing torque Tu is applied to the barb anchor, particularly to a screw or bolt received in the barb anchor body, in a direction opposite to the screwing-in direction I, the reverse tooth face or faces may bear a reaction Fr by bearing on the osseous tissue, thus resisting the unscrewing torque Tu. Since the reverse tooth face or faces may be tilted in relation to the axis of rotation R at the reverse angle β, may effect an equivalent reaction force Feq which acts to resist an outwards movement of the barb anchor. Thus, resisting unscrewing of the barb anchor is effected by compression, instead of relying on shear forces between the barb anchor body and the substrate, resist unscrewing. Since compression forces may be considerably greater than shear forces between the barb anchor body and the substrate, this may provide enhanced performance of the barb anchor, while assisting in stabilizing the barb implant in the bone tissue. This may assist and enhance healing following an implant procedure.