A polyaxial bone anchoring device is provided, comprising a bone anchoring element (1) having a shank (2) to be anchored in the bone and a head (3) a receiving part (5) coupled to the shank and configured to pivotably receive the head, and having a channel (56) for receiving a rod (6) and a central axis (C) a pressure member (7) arranged in the receiving part and configured to exert pressure onto the head to lock the head in the receiving part a locking assembly (8, 8, 8", 8) that is insertable into the channel, the locking assembly comprising a first locking member (9) having a first end (91) and a second end (92) facing the pressure member (7), a bore (94) passing through the first locking member from the first end to the second end, the bore having a bore axis a second locking member (10) provided in the bore of the first locking member, the second locking member having a first end (101) directed towards the first end (91) of the first locking member and a second end (102) and an engagement portion (106, 107) for a tool characterized in that in a first configuration, the first locking member (9) and the second locking member (10) are rotationally fixed relative to each other such that by rotating the second locking member in a first direction, the first locking member (9) is advanced to contact the pressure member (7) with at least a surface portion of its second end (92) and in a second configuration, the second locking member (10) is rotatable within the first locking member (9) such that by rotating the second locking member in the first direction, the second locking member (10) is advanced to contact the rod with at least a surface portion of its second end (102).本案提供一種多軸式骨骼固定裝置,包括骨骼固定元件(1),具有要固定於骨骼之幹部(2),和頭部(3);容納件(5),聯結於幹部,構成可樞動容納頭部,並有槽溝(56)以容納桿件(6),以及中央軸線(C);壓力構件(7),配置在容納件內,構成可施壓於頭部,把頭部鎖定於容納件內;鎖定總成(8,8,8",8)可插入於槽溝內,鎖定總成包括第一鎖定構件(9),具有第一端(91)和朝向壓力構件(7)之第二端(92),從第一端通過鎖定構件到第二端之腔孔(94),腔孔具有腔孔軸線;第二鎖定構件(10),設在第一鎖定構件之腔孔內,第二鎖定構件有第一端(101),指向第一鎖定構件之第一端(101)、第二端(102)和工
