When the bones that join the head and neck are putting pressure on the brain, spinal cord, or nerves, traction is usually needed to realign (reduce) the structures. Traction typically involves a device that encircles and is fixed to the head. This device is called a halo crown or ring. It is fixed to the person’s head with four pins—two on each side of the head. The halo ring is also attached to a brace (called a halo vest) around the person's torso to immobilize the neck.