Mechanical traction is defined as the application of a mechanical force to the body in a way that separates or attempts to separate the joint surfaces and elongate the surrounding soft tissues.
Spinal traction is used to distract joint surfaces and stretch soft tissues.
Joint distraction is defined as the separation of two articular surfaces perpendicular to the plane of the articulation. For distraction to occur in the spine, the force applied must be great enough to cause sufficient elongation of the soft tissues surrounding the joint to allow the joint surfaces to separate. Smaller amounts of force will increase the tension on, or elongate the soft tissues of the spine without separating the joint surfaces. A force of seven percent of total body weight is sufficient to distract the cervical vertebrae, according to one study, while 25 pounds is necessary according to another study. Amount of time the traction is applied.