A polyaxial bone anchoring device is provided including an anchoring element (1) having a shank (2) for anchoring in the bone and a head (3), the head comprising a spherically-shaped outer surface portion (3a) a receiving part (4) configured to be pivotably connected to said head (3), the receiving part having a first end (4a), a second end (4b), a central axis (C) extending through the first end (4a) and the second end (4b), a channel (42) for receiving a rod (100), an accommodation space (44) for accommodating the head (3), the accommodation space (44) having a lower opening (45) at the second end (4b), and a coaxial passage (41) extending from the first end (4a) into the accommodation space (44), a cap member (6, 6) that is arranged at least partially in the accommodation space (44), the cap member (6, 6) having a first portion (61) that is configured to be positioned at least partially around the head (3), wherein the first portion (61) is expandable in the accommodation space (44) to allow insertion of the head (3) and compressible to exert pressure onto the head (3) a sleeve-like insert piece (5) configured to be positioned at least partially around the first portion (61) of the cap member (6, 6), wherein the sleeve-like insert piece (5) comprises a spherically-shaped outer surface portion (51) and is configured to pivot in the receiving part (4).本案提供一種多軸式骨骼固定裝置,包含一固定元件(1),具有供固定於骨骼內之一幹部(2),和一頭部(3),該頭部包括一球形外表面部(3a);一容納件(4),構成可樞動連接於該頭部(3)內,該容納件具有、一第一端(4a)、一第二端(4b)、一中心軸線(C),供延伸貫穿該第一端(4a)和該第二端(4b),一槽溝(42),供容納一桿件(100),一包容空間(44),供包容該頭部(3),該包容空間(44)具有一下開口(45),在該第二端(4b),和一共軸通道(41),從該第一端(4a)延伸進入該包容空間(44)內;一帽蓋構件(6,6),配置成至少部份在該包容空間(44)內,該帽蓋構件(6,6)具有一第一部(61),構成至少部份定位在該頭部(3)周圍,其中該第一部(61)可在該包容空間(44)內撐張,讓該頭部(3)插入,並可壓縮,施壓於該頭部(3);一套筒般插件(5),構成至少部份定位在該帽蓋構件(6,6)的該第一部(61)周圍,其中該套筒般插件(5)包括一球形外表面部(51),並構成在該容納件(4)內樞動。1‧‧‧骨骼固定元件2‧‧‧螺紋幹部3‧‧‧頭部3a‧‧‧頭部球形外表面部3b‧‧‧凹部4‧‧‧容納件5‧‧‧套筒般插件6‧‧‧帽蓋構件7‧‧‧桿件容納元件8‧‧‧鎖定裝置8a‧‧‧第一鎖定元件8b‧‧‧第二鎖定元件9‧‧‧銷件41‧‧‧通道42‧‧‧U形凹部43‧‧‧陰螺紋61‧‧‧帽蓋構件第一部64‧‧‧開縫65‧‧‧傾斜下緣部71‧
