| abstract |
A fastener for anchoring in a bore in a bone has a screw having a substantially cylindrical outer surface formed with a helical screwthread. This screw has at its screwthread a thread diameter and between the turns of the thread at the surface a root diameter smaller than the thread diameter. A synthetic-resin anchor sleeve of a resilient fitted in the bore is of an outside diameter corresponding generally to the diameter of the bore and has an outer end formed with an outwardly open polygonal-section recess, an inner end formed with an inwardly open and transversely throughgoing slot, an outer end portion of an inside diameter greater than the root diameter but smaller than the thread diameter, an inner end portion of an inside diameter smaller than the root diameter, and an external helicoidal screwthread extending about two-thirds of the length of the sleeve from its inner end toward its outer end. |