A spinal implant (100) includes an anchoring part (110) adapted to be anchored to a vertebra and having first connecting elements (112), and a mounting part (120) including both an internal axial housing (151) to receive transversely a connecting rod (30), this axial housing being terminated beside the anchoring part (110) by a bottom (156), and also second connecting elements that cooperate with the first connecting elements to form a ball-joint connection between the anchoring part and the mounting part. The spinal implant includes retaining elements that are situated near the bottom of the axial housing of the mounting part that are adapted to fasten a locking member in a stationary so-called locking position in which the ball-joint connection formed by the first and second connecting elements is locked to fasten the anchoring part and the mounting part in rotation relative to each other about at least two orthogonal axes.