Where do pressure ulcers usually form?
Pressure ulcers form where bone causes the greatest force on the skin and tissue and squeezes them against an outside surface. This may be where bony parts of the body press against other body parts, a mattress or a chair. Nerves normally tell the body when to move to relieve pressure on the skin but people in bed who are unable to move may get pressure ulcers after as little as 1-2 hours. Those people in chairs who cannot move can get pressure ulcers in even less time because the force on the skin is greater. Their position should be changed every hour. In those who must stay in bed, most pressure ulcers form on the lower back below the waist, the hip bone and on the heels. In people in chairs or wheelchairs, the exact spot where pressure ulcers form depends on the sitting position. Pressure ulcers can also form on the knees, ankles, shoulder blades, back of the head and spine.
