Abstract: The invention relates to a clamp element for external fixator apparatuses of the rod and ring type used for stabilizing bone fractures in orthopedic surgery; a clamp connector secures at least one of the bone fragment stretching wires and the bone screws to the rings. The invention comprises a swivel joint comprising a first part and a second part associated with each other around a common pivot axis, each part being formed with at least one hole of a predetermined diameter for clamping the stretching wire or the bone screw therein. Also provided on each of the parts are clamping mechanisms for attaching to a rod or to a ring of the fixator device. The clamping mechanisms are used for clamping the stretching wire or the bone screw in the part of the swivel joint which is not connected to the rod or to the ring.