| 摘要 |
The invention relates to a polyaxial screw having a mechanical thread, comprising a friction means (12) arranged between the head (3) of the bone-anchoring threaded portion (2) and the head (9) of the anchoring portion having the mechanical thread (4), as well as a retaining means (13, 18) for ensuring that the anchoring portions (2, 4) cannot be separated from one another while guaranteeing the freedom of vertical translatable and angularly pivotable movement of the anchoring portion having the mechanical thread (4) relative to said bone-anchoring threaded portion (2) in order to be capable of axially prepositioning said mechanical anchoring portion (4), prior to immobilising same, relative to the axial anchoring position of the bone-anchoring threaded portion (2). |
