An assembly or structure of a bone anchor (10 200) comprising: a bone anchor (12 212) having a proximal head (18) and a distal rod (20 200) designed to fit or join the bone, so that the distal rod has a first threaded section (50 250) that is distal to proximal head, a second threaded section (52) that is distal and adjacent to the first threaded section, and a third threaded section (54) is distal and adjacent to the second threaded section, and wherein the bone anchor includes a conduit or central passage (40) extending from the proximal head through the distal rod and the first threaded section having a first diameter greater (56), a smaller first diameter (58) and a first length (60), so that the first larger diameter and the smaller first diameter are constant along the first length of the first threaded section, the second section screw has a second larger diameter (62), one second smaller diameter (64) and a second length (66), so that the larger second diameter and the second diameter smaller taper in a proximal to distal direction along the second length of the second threaded section, and wherein the second larger diameter and the second diameter smaller are lower, respectively, the first larger diameter and the first lower along the second length of the second threaded section diameter, the third threaded section has a third large diameter (68 ), a smaller third diameter (70) and a third length (72), so that the third largest diameter tapers in a proximal to distal direction along the third length of the third threaded section, and the third largest diameter it is smaller than the second largest along the third length of the third threaded section diameter, and so that the third smaller diameter is constant along the third length of the third section ro SCADA and the third smaller diameter equals the second smaller diameter at a transition from the second threaded section to the third threaded section, a receiving member (14) receives or houses a componen
