Causes

Bedsores are caused by pressure against the skin that limits blood flow to the skin. Limited movement can make skin vulnerable to damage and lead to development of bedsores.

Three primary contributing factors for bedsores are:

• Pressure. Constant pressure on any part of your body can lessen the blood flow to tissues. Blood flow is essential for delivering oxygen and other nutrients to tissues. Without these essential nutrients, skin and nearby tissues are damaged and might eventually die.

  For people with limited mobility, this kind of pressure tends to happen in areas that aren't well padded with muscle or fat and that lie over a bone, such as the spine, tailbone, shoulder blades, hips, heels and elbows.

• Friction. Friction occurs when the skin rubs against clothing or bedding. It can make fragile skin more vulnerable to injury, especially if the skin is also moist.
• Shear. Shear occurs when two surfaces move in the opposite direction. For example, when a bed is elevated at the head, you can slide down in bed. As the tailbone moves down, the skin over the bone might stay in place — essentially pulling in the opposite direction.