Abstract: Traction device comprising:a frame defining a median planea pelvis support connected to the frame and adjustable laterally with respect to said median plane,two arms articulated in said median plane, the first arm being a central traction arm, articulated so as to be mobile horizontally and vertically, the second arm being a central counter-extension arm articulated so as to be mobile horizontally, said arms being provided with means for blocking in position and with traction means.The means for blocking the central arm comprises a clamping sleeve co-axial to the arm and manoeuvrable in rotation, passing through intersecting meridian slots of two spherical lunes articulated on orthogonal axes, the sleeve comprising two inverted threads cooperating with jaws mobile in translation on the sleeve and located on either side of the intersection of the lunes so as to cause, by moving them closer to or away from each other, the blocking by friction or unblocking of the arm.