A pressure injury (pressure sore or bed sore) is an injury to the skin and the tissue underneath as a result of constant pressure on the skin. Pressure injuries may also be cause by shear (a tear caused by pressure + friction) or by sitting in dampness. In areas of the body where you do not have feeling, you will not notice when you start to feel sore. People with reduced mobility and sensation are at a greater risk. High risk areas are the tailbone, backside, hips and heels.