The invention relates to a multiaxial pedicle screw for vertebral osteosynthesis, said invention including: a pedicle screw (10) that is to be implanted into the bone portion of a vertebra and comprises a spherical head (12) having a recess (13) for the rotation of said pedicle screw (10) a socket (20) that is hinged onto the spherical head (12) of the pedicle screw (10) and is provided with two diametrically opposed side grooves (21) for receiving a connection rod (30) a tightening means (40) for maintaining the position of the connection rod (30) that is engaged into said socket (20) and a locking means that is positioned between said spherical head (12) of the pedicle screw (10) and the socket (20). According to the invention, the locking means is formed of a ring (50), at least the base or distal portion (52) of which consists of a cold-compactible material having a resilient deformation capacity. Said locking means enables the locking of the socket (20) in a desirable direction relative to the spherical head (12) of the pedicle screw (10) according to the position of the pedicle screw (10) after the anchoring thereof.La invención se refiere a un tornillo pedicular multiaxial para osteosíntesis vertebral, la invención que incluye: un tornillo pedicular (10) que se va a implantar en la porción ósea en una vértebra y que comprende un cabezal esférico (12) que tiene una depresión (13) para la rotación del tornillo pedicular (10) un receptáculo (20) que se articula por charnela sobre el cabezal esférico (12) del tornillo pedicular (10) y se proporciona con dos ranuras laterales diametralmente opuestas (21) para recibir una varilla de conexión (30) un medio de apriete (40) para mantener la posición de la varilla de conexión (30) que se acopla en el receptáculo (20) y un medio de fijación que se coloca entre el cabezal esférico 12 del tornillo pedicular (10) y el receptáculo (20). De acuerdo a la invención, el medio de fijación se forma de un anillo (50), al menos la
