Elevation is part of the basic injury treatment of the R.I.C.E principle, which is:
By elevating a swollen area it allows the fluid to drain away. When elevating it is best to have the swollen area above heart level in order to increase the body’s ability to drain. While elevating a limb, such as the leg, it is important that the joint (the knee in this example) be supported to prevent undue pressure. Elevating a body part is a great time to also apply ice which can further reduce any inflammation in the area your working with.