The prosthesis has plates (10, 20) whose contact surfaces (11, 22) are respectively contacted to two vertebrae (V1, V2). An intermediate body (30) is interposed to a contact sliding between the plates. A control unit (40) controls the displacement of the body between positions (P1, P2). The body is arranged with respect to the plates, so that the contact surfaces of the plates are at the distance (Dd) that is higher than the given distance (dnd) in one of the positions of the body. Connecting units (50) connect the body with one of the plates and the vertebra when the body is in the position.
