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) having a first end (5a) and an open second end (5b) with a bounding edge and a hollow interior portion (54) in communication with the open second end for receiving the head (3) therein, the head receiving part (5) 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) configured to cover the rod and to engage the head receiving part a locking element (9) extending through the cap and configured to engage the rod wherein the cap (8) and the locking ring (6) are rotatable with respect to the head receiving part (5) when the rod is inserted and upon tightening of the locking element the rod and the bone anchoring element 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),有可固定於骨骼之軸部(2),和頭部(3);頭部容納件(5),有第一端(5a),限界邊緣之開口第二端(5b),與開口端第二端相通之空心內部(54),可容納頭部(3);頭部容納件(5)具撓性,得以夾帶頭部;鎖環(6),安裝在頭部容納件周圍,鎖環有桿件容納部(63,64);其中頭部(3)可在頭部容納件內樞動,並可藉鎖環(6)壓縮頭部容納件而鎖定在某一角度;螺帽(8),構成覆蓋於桿件,並與頭部容納件結合;鎖定元件(9),延伸貫穿螺帽,並構成結合桿件;其中當桿件插入時,螺帽(8)和鎖環(6)可相對於頭部容納件(5)轉動,而旋緊鎖定元件時,桿件和骨骼固定元件即彼此相對鎖定。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5c‧‧‧共軸貫穿孔6‧‧‧鎖環7‧‧‧桿件8‧‧‧螺帽8a‧‧‧螺帽第一端8b‧‧‧螺帽第二端9‧‧‧鎖定元件51‧‧‧邊緣部53‧‧‧錐形外表面部63‧‧‧凸部64‧‧‧圓形截面狀凹部81‧‧‧貫穿螺孔82‧‧‧方形凹部84‧‧‧凸緣86‧‧‧結合部87‧‧‧開縫C‧‧‧中心軸線
