Abstract: Implants and related methods for achieving dynamic fixation are disclosed. The implant comprises a head portion at a proximal end of the implant comprising external threads and a first axial through hole, and an anchor portion extending from the head portion at a distal end of the implant comprising external threads and a second axial through hole in communication with the first axial through hole. The implant further comprises a flexible constraint member extending within the first and second axial through holes comprising a first end portion coupled to the head portion and a second end portion coupled to the anchor portion. At least one of the head portion and the anchor portions forms a breakaway portion with aligned internal and external circumferential grooves configured to concentrate stress thereat such that the breakaway portion fractures via forces acting on the implant to separate the head and anchor portions.