(pressure) ulcers are breaks in the skin due to prolonged exposure to a surface via compression.
This wound may be susceptible to infection and needs to be treated. They are staged (1, 2, 3, 4) and the higher the stage, the deeper the ulcer. In the long term a scar may form, but the long term concern is the risk of infection ( especially bone = osteomyelitis
Answer assisted by Michael Erickson, Medical Student