Pressure injuries are usually caused by unrelieved pressure on the skin. They often form on skin that covers bony areas. The most common sites are the back of the head and ears, the shoulders, the elbows, the lower back and buttocks, the hips, the inner knees, and the heels.

Pressure injuries may also form in places where the skin folds over itself. And they can occur where medical equipment puts pressure on the skin. For example, they may form where oxygen tubing presses on the ears or cheeks.