What is the reason for a thick leg and a thin leg?

One leg thick and one leg thin may be caused by congenital dysplasia, or may be caused by trauma fracture, local tissue swelling caused by inconsistent size, but also suspected to be a lower limb venous thrombosis, unilateral limb blood circulation is not smooth, a large amount of blood stays in the lower limbs caused. You need to go to the hospital for leg X-ray examination to /confirm/i.