Abstract: A sacral support saddle has an eye (36) for receiving a first screw (38) and a cylindrical hole (37) with an axis (X5) of inclination such that, when the saddle (29) is positioned on the sacrum, the screw (38) is inserted into the sacral plate and towards the upper axis of the latter. A U-shaped body (32) delimits a channel (34) for receiving a rod, and a stopper (7) locks the rod (8) in this body. A hole (33) for passage of a second screw (42) has an axis (Y5) divergent relative to the axis (X5) of the hole of the eye in such a way as to be oriented towards the iliac mass when the saddle is positioned on the sacrum. This saddle and its two screws (38, 42) provide for a reliable anchoring of the rod of the device to the sacrum by virtue of the penetration of the screws into solid regions of the latter. This, in practice, avoids any risk of pulling out and, consequently, a second surgical intervention.