| 摘要 |
A polyaxial pedicle screw includes a threaded shaft portion for anchoring the pedicle screw in a vertebra, the pedicle screw having one axial end provided with a shaft head which is coupled to a mounting sleeve for a longitudinal beam in a rotatable and/or pivotable manner, including a fixing device for the selective positional fixation of the mounting sleeve with respect to the shaft portion. The fixing device includes a locking element as well as a counterforce part which is formed so as to be separate from the pedicle screw and counteracts the holding force of the locking element, preferably a grub screw or threaded nut, and is designed and/or retained in such a manner that the holding force of the locking element can be selectively released by means of the counterforce part, viz. is without any effect. |
