A pressure ulcer is an injury to the skin as a result of constant pressure due to impaired mobility. The pressure results in reduced blood flow and eventually causes cell death, skin breakdown, and the development of an open wound. Pressure ulcers can occur in persons who are wheelchair-bound or bed-bound, sometimes even after a short time (2 to 6 hours). If the conditions leading to the pressure sore are not rapidly corrected, the localized skin damage will spread to deeper tissue layers affecting muscle, tendon, and bone. Common sites include the sacrum (tailbone), back, buttocks, heels, back of the head, and elbows. If not adequately treated, open ulcers can become a source of pain, disability, and infection. The August 23/30, 2006, issue of JAMA includes an article about prevention of pressure ulcers.