A polyaxial bone anchoring device is provided including a bone anchoring element (1) having a shank (2) for anchoring in the bone and a head (3), a receiving part (5, 5) for receive the head of the bone anchoring element and for receiving a rod (100), the receiving part including an upper member (8, 8) with a top end (81) and a bottom end (82), a central axis (C) extending through the top end and the bottom end, a head receiving portion (84) with a passage (85) at the bottom end (82) for introducing the head and a channel (86) for receiving the rod at the top end (81) a lower member (10, 10) having a top end (101) and a bottom end (102) and a passage (103,104) extending from the top end to the bottom end, the lower member being connectable to the upper member from the bottom end (82) of the upper member wherein at least one clamping member (20, 200) is provided at or near the bottom end (82) of the upper member and wherein the clamping member (20, 200) is configured to reduce the diameter of the passage (85) of the head receiving portion (84) of the upper member (8, 8) when the lower member is connected to the upper member such as to hold the head (3) when the head is inserted in the head receiving portion (84).本案提供一種多軸式骨骼固定裝置,包含骨骼固定元件(1),具有要固定於骨骼的幹部(2),和頭部(3);容納件(5,5),以供容納骨骼固定元件之頭部,並供容納桿件(100),容納件包含:上構件(8,8),有頂端(81)和底端(82),延伸貫穿頂端和底端之中央軸線(C),頭部容納部(84),在底端(82)有供引進頭部之通道(85),頂端(81)有供容納桿件之槽溝(86);下構件(10,10),有頂端(101)和底端(102),從頂端延伸到底端之通道(103,104),下構件可從上構件之底端(82)連接到上構件;其中在或接近上構件底端(82)設有至少一夾持構件(20,200),且其中夾持構件(20,200)構成是,當下構件連接於上構件時,縮小上構件(8,8)的頭部容納部(84)之通道(85)直徑,諸如當頭部插入頭部容納部(84)內時,可把持頭部(3)。1‧‧‧骨骼固定元件3‧‧‧球形截面頭部4‧‧‧凹部5‧‧‧容納件6‧‧‧壓力元件7‧‧‧鎖定元件8‧‧‧上構件10‧‧‧下構件20‧‧‧球體61‧‧‧壓力元件頂端62‧‧‧壓力元件底端63‧‧‧圓筒形凹部65‧‧‧共軸貫穿孔81‧‧‧上構件頂端82‧‧‧上構件底端85‧‧‧通道86‧‧‧U形凹部90‧‧‧螺紋外表面部91‧‧‧橫越腔孔100‧‧‧桿件C‧‧‧中央軸線E‧‧‧頭部球體最大直徑
