Abstract: An apparatus for applying a traction force to an appendage of a subject which includes a one-way gripping device having a channel and a cam. The cam is pivotal so that a gripping surface of the cam can be positioned in the channel. A force applicator which can be a rope or cable extends through the channel of the one-way gripping device. The force applicator is free to slide through the channel of the one-way gripping device in one direction, but is gripped by the cam and prevented from moving in an opposite direction. One end of the force applicator is secured to an appendage of a subject. A traction force is applied to the appendage by pulling the force applicator through the one-way gripping device.