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 member (8) that is insertable into the channel, the locking member comprising a top end (81) and a bottom end (82) facing the pressure member a deformable first portion (85) and a second portion (84) provided at the bottom end wherein, when the locking member is advanced into the charnel in the direction of the central axis (C), first the deformable first portion (85) comes into contact with the pressure member (7) and is deformed resulting in a load applied to the pressure member that clamps the head, and thereafter the second portion (84) comes into contact with the rod and clamps the rod.本案提供一種多軸式骨骼固定裝置,包括骨骼固定元件(1),具有要固定於骨骼內之幹部(2),和頭部(3);容納件(5),聯結於幹部,並構成可樞動容納頭部,並有槽溝(56),可供容納桿件(6)和中心軸線(C);壓力構件(7),配置在容納件內,並構成施壓於頭部,把頭部鎖定於容納件內;鎖定構件(8),可插入槽溝內,鎖定構件包括頂端(81)和朝向壓力構件之底端(82);設在底端之可變形第一部位(85)和第二部位(84);其中當鎖定構件按中心軸線(C)方向推進入槽溝內時,首先可變形第一部位(85)即與壓力構件(7)接觸,並且變形,造成施加於壓力構件之負荷,並夾持頭部,然後第二部位(84)再與桿件接觸,並夾持桿件。3‧‧‧頭部5‧‧‧容納件6‧‧‧桿件7‧‧‧壓力構件8‧‧‧鎖定構件51‧‧‧容納件頂端52‧‧‧容納件底端53a‧‧‧腔孔第一段53b‧‧‧腔孔第二段59‧‧‧陰螺紋71a‧‧‧擴大表面部74‧‧‧球形凹部84‧‧‧圓筒形部85‧‧‧錐形部C‧‧‧中心軸線
