The lock element is formed, in order with the bone connecting anchor of the multi axes to be used, meeting with the head of the aforementioned bone connecting anchor underneath and, becoming opposite to underneath the description above and, it is the abbreviation cylindrical condition which possesses with the surface where the male screw was formed. The aforementioned lock element has the first concave section in order at least to accept the portion of the aforementioned head underneath the description above, the screw driver possesses the second concave section in order to engage above the description above. The aforementioned second concave section is located outside the center above the description above. The aforementioned head has the part where maximum diameter is accompanied, first level L1 is stipulated by the summit of trajectory of the circle which the aforementioned maximum diameter draws around the aforementioned head, second level L2 is stipulated by bottom of the aforementioned second concave section, L2 is the level which is not higher than L1.< Selective figure >Figure 17a)ロック要素は多軸の骨接合アンカーとともに使用されるよう構成され、前記骨接合アンカーの頭部と対面する下側と、前記下側と反対になる上側と、雄ねじが形成された表面部とを有する略円筒形状である。前記ロック要素は、少なくとも前記頭部の一部を受け入れるための第一凹部を前記下側に有し、ねじ回しと係合するための第二凹部を前記上側に有する。前記第二凹部は前記上側の中心の外側に位置する。前記頭部は、最大直径を伴う部分を有し、前記最大直径が前記頭部周りに描く円の最高点によって第一レベルL1が規定され、前記第二凹部の底部によって第二レベルL2が規定され、L2はL1よりも高くないレベルである。【選択図】図17a)
