PROBLEM TO BE SOLVED: To provide a bone anchor that allows the head of the bone anchor to perform a limited motion after being anchored into a bone or a vertebrae.SOLUTION: A dynamic bone anchor comprises: an anchor member having a first end, a second end, a tubular section between the first end and the second end, a longitudinal axis extending from the first end to the second end, an outer surface, and a bone engagement structure for engaging the bone in at least a portion of the outer surface； and a longitudinal core member, which is at least partially provided in the tubular section and is connected to the anchor member at a second portion of the core member, and which has a first portion that is not connected to the anchor member and that is movable with respect to the anchor member. In addition, the core member is made at least partially of a first material that comprises a Ni--Ti based shape memory alloy.【課題】骨アンカーを骨または椎骨内に固定した後、限定的な動作を行なうことができる骨アンカーの頭部を可能にする、動的骨アンカーを提供する。【解決手段】第１の端と、第２の端と、第１の端と第２の端との間のチューブ状セクションと、第１の端から第２の端に延びる長手方向軸と、外面と、外面の少なくとも一部に骨を係合するための骨係合構造とを有するアンカー部材と、長手方向コア部材とを備え、長手方向コア部材は、チューブ状セクションに少なくとも部分的に設けられ、かつ、コア部材の第２の部分でアンカー部材に接続されており、さらに、アンカー部材に接続されておらず、かつ、アンカー部材に対して可動である第１の部分を有し、コア部材は、Ｎｉ－Ｔｉ系形状記憶合金を含む第１の材料から少なくとも部分的になる。【選択図】図１
