Pathogenic factors of traction, elevation, and pressure during application of short leg cast used for traction can cause compartment syndrome. A, Below-knee cast is applied while patient is on spica frame. B, Traction is applied to short leg cast to produce distraction at fracture site. The remainder of cast is applied, fixing relative distance between leg and torso. C, After child awakens from general anesthesia, there is shortening of femur from muscular contraction, which causes thigh and leg to slip somewhat back into spica. This causes pressure at corners of cast (arrows).