A locking device for securing a rod-shaped element is provided in a receiving part of a bone anchor, said locking device comprising: a first locking member (6, 600, 6’) having a first end (61, 601) and a second end (62, 602) which is provided with an external thread (63, 603) on at least a portion thereof, a coaxial bore (64, 604) passing entirely through the first locking member the coaxial bore having a bore axis (C) and an internal thread (65, 605) provided in at least a portion of said bore, a second locking member (7, 700, 7’), the second locking member having a first end (71, 701) and a second end (72, 702), an outer surface with an external thread (73, 703) in at least a portion thereof which cooperates with the internal thread provided at said bore of the first locking member, wherein the second locking member (7, 700, 7’) is movable along the bore axis (C) by rotating it and wherein a path of advancement of the second locking member is limited towards the first end by a first stop (66, 606c) and towards the second end (62b,606d) by a second stop.本案係關於一種把桿狀元件固設於骨骼固定器容納件用之鎖定裝置,包括:第一鎖定構件(6,600,6’),具有第一端(61,601)和至少一部份設有陽螺紋(63,603)之第二端(62,602),共軸腔孔(64,604),完全貫穿第一鎖定構件,共軸腔孔具有腔孔軸線(C),該腔孔至少一部份設有陰螺紋(65,605);第二鎖定構件(7,700,7’),具有第一端(71,701)和第二端(72,702),外表面至少一部份有陽螺紋(73,703),與第一鎖定構件的該腔孔所設陰螺紋嚙合,其中第二鎖定構件(7,700,7’)可藉轉動而沿腔孔軸線(C)運動,又其中第二鎖定構件之前進途徑,朝第一端受到第一止檔部(66,606c),而朝第二端受到第二止檔部(62b,606d)之限制。6‧‧‧第一鎖定元件7‧‧‧第二鎖定元件61‧‧‧第一鎖定元件第一端62‧‧‧第一鎖定元件第二端62b‧‧‧環形支座63‧‧‧陽螺紋66‧‧‧支座67‧‧‧結合結構71‧‧‧第二鎖定元件第一端72‧‧‧第二鎖定元件第二端74‧‧‧無螺紋部76‧‧‧共軸凹部d3‧‧‧第一鎖定元件螺紋根部內徑d4‧‧‧環形支座內徑
