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 head receiving part (5,5) having a first end (5a) and an open second end (5b) a central axis (C) extending through the first end (5a) and the second end (5b) and a hollow interior portion (56) in communication with the open second end for receiving the head (3) therein, the head receiving part being flexible so as to allow clamping of the head a locking ring (6) mounted around the head receiving part, the locking ring having a rod receiving portion (63,64) wherein the head (3) is pivotable in the head receiving part and can be locked at an angle by compressing the head receiving portion by means of the locking ring (6) a cap (8,8) configured to cover the rod and to engage the head receiving part and having a first end (8a) and a second end (8b) and a central axis (C) extending through the ends and two opposite (87a,87b 87a,87b) extending in the direction of the central axis a locking element (9) extending through the cap and configured to engage the rod wherein the cap (8,8) is rotatable relative to the head receiving part (5) between a first position in which the legs are out of engagement with the head receiving part and a second position in which the legs engage the head receiving part and wherein upon tightening of the locking element the rod and the bone anchoring element (1) are locked with respect to each other.本案提供一種多軸式骨骼固定裝置,包含骨骼固定元件(1),有可固定於骨骼內之軸部(2),和頭部(3);頭部容納件(5,5),有第一端(5a)和開口第二端(5b),延伸貫穿第一端(5a)和第二端(5b)之中心軸線(C),以及空心內部(56)與開口第二端相通,以容納頭部(3),頭部容納件係撓性,以便夾帶頭部;鎖環(6),安裝在頭部容納件周圍,鎖環具有桿件容納部(63,64);其中頭部(3)可在頭部容納件內樞動,並可利用鎖環(6)壓縮頭部容納件而鎖定角度;螺帽(8,8),構成覆蓋桿件,並結合頭部容納件,具有第一端(8a)和第二端(8b),延伸貫穿末端之中心軸線(C),以及按中心軸線方向延伸之二對立股部(87a,87b;87a,87b);鎖定元件(9),延伸貫穿螺帽,構成結合桿件;其中螺帽(8,8)可相對於頭部容納件(5),在股部與頭部容納件解脫的第一位置,和股部與頭部容納部結合的第二位置之間轉動,又其中旋緊鎖定元件時,桿件和骨骼固定元件(1)即彼此鎖定。1‧‧‧骨骼固定元件2‧‧‧軸部3‧‧‧頭部5‧‧‧頭部容納件5a‧‧‧頭部容納件第一端5b‧‧‧頭部容納件第二端6‧‧‧鎖環7‧‧‧桿件8‧‧‧螺帽8a‧‧‧螺帽第一
