The present invention relates to a spacer intended to be introduced between two elements of a vertebral body. This spacer comprises a tube, a spacer module and an actuating system of the spacer module, the actuating system comprising at least one rod which is, on one hand, accessible from a distal end of the tube and, on the other hand, connected to said spacer module. The spacer is characterized in that the spacer module comprises two blades coplanar to a longitudinal axis of the rod, these blades being movable between a closed position in which the blades are substantially parallel to the longitudinal axis of the rod, and a deployed position in which the blades have an arched shape, and in that in their deployed position, these blades are asymmetrical with respect to each other and with respect to said longitudinal axis of the rod.
