Abstract: The invention relates to an implant (10) to sheath and/or reinforce bone and/or to anchor bone screws. The implant (10) takes the shape of a dowel which is capable of spreading and/or swelling and/or interlocking in bone in some other way. The implant (10) preferably presents ring-like bulges (16) on its outer surface and an internal screw thread (20) on its inner surface to screw in bone screws. Implant (10) improves the tensile strength when anchoring bone screws (Figure 1).