| 摘要 |
According to the invention, - the cavity (5) of the screw body (2) presents a portion with an enlarged cross-section (16) forming a chamber, positioned such that it is set back from the proximal surface of said head (6), over a sufficient distance so that first slots (7) and first expandable portions (8) constitute gripping means to drive the screw (1); - said expansion rod (3) comprises a proximal head (21) equipped with gripping means (22) to drive it in rotation, intended to be found in said chamber in the non-expanded position of the screw head (6); - the cavity (5) has a first portion (15) with a limited cross-section located at said expandable portions (8), this limited cross-section portion (15) being intended to cooperate with the head (21) to achieve expansion of said expandable portions (8) while also defining a passageway having a cross-section sufficient to allow access, from the outside of the screw (1), to the gripping means (22) comprised by the expansion rod (3). |
