A device for tensioning a surgical thread comprising: - an elongated body extending along a longitudinal axis and having a tip portion adapted to be arranged in contact with a knot of a surgical thread wound about a patient's bone, and - a maneuvering member, connected to said elongated body, adapted to be arranged outside the patient's body and having respective coupling portions for coupling opposite ends of said surgical thread wound and knotted about said bone, said opposite ends of the surgical thread being reversibly constrainable to said respective coupling portions in a use configuration of the device; wherein said elongated body is connected to said maneuvering member by means of a screw and nut-screw mechanism configured to mutually space apart or approach said elongated body and said maneuvering member; wherein said elongated body and said maneuvering member are configured to be mutually spaced apart along a movement axis coinciding with the longitudinal axis in order to tension the opposite ends of the surgical thread so as to tighten the surgical thread about the bone, wherein said tip portion has a groove shaped to receive at least partially said knot in the use configuration of the device, said groove extending perpendicularly to the movement axis to open on opposite sides of a sidewall of said elongated body at respective return portions along which the opposite ends of the surgical thread can be returned toward the coupling portions, so that the opposite ends of the surgical thread can be arranged tangentially to the bone over a first stretch between the return portions inside the groove, and transversely to said bone along respective second stretches, having a greater length than the first stretch, between the return portions and the coupling portions; wherein said maneuvering member comprises: - a knob which is rotatable about the movement axis for screwing or unscrewing the screw and nut-screw mechanism, and - a sleeve on which the two coupling portions are obtained; said knob being rotationally connected to said sleeve. - an elongated body extending along a longitudinal axis and having a tip portion adapted to be arranged in contact with a knot of a surgical thread wound about a patient's bone, and - a maneuvering member, connected to said elongated body, adapted to be arranged outside the patient's body and having respective coupling portions for coupling opposite ends of said surgical thread wound and knotted about said bone, said opposite ends of the surgical thread being reversibly constrainable to said respective coupling portions in a use configuration of the device; wherein said elongated body is connected to said maneuvering member by means of a screw and nut-screw mechanism configured to mutually space apart or approach said elongated body and said maneuvering member; wherein said elongated body and said maneuvering member are configured to be mutually spaced apart along a movement axis coinciding with the longitudinal axis in order to tension the opposite ends of the surgical thread so as to tighten the surgical thread about the bone, wherein said tip portion has a groove shaped to receive at least partially said knot in the use configuration of the device, said groove extending perpendicularly to the movement axis to open on opposite sides of a sidewall of said elongated body at respective return portions along which the opposite ends of the surgical thread can be returned toward the coupling portions, so that the opposite ends of the surgical thread can be arranged tangentially to the bone over a first stretch between the return portions inside the groove, and transversely to said bone along respective second stretches, having a greater length than the first stretch, between the return portions and the coupling portions; wherein said maneuvering member comprises: - a knob which is rotatable about the movement axis for screwing or unscrewing the screw and nut-screw mechanism, and - a sleeve on which the two coupling portions are obtained; - a knob which is rotatable about the movement axis for screwing or unscrewing the screw and nut-screw mechanism, and - a sleeve on which the two coupling portions are obtained; said knob being rotationally connected to said sleeve.