It was reported in all but one Grade 1 PU with most of the painful PU being at the sacrum, buttocks and heels.
[bmcnurs.biomedcentral.com]
If not adequately treated, open ulcers can become a source of pain, disability, and infection.
[jamanetwork.com]
[…] or tender “pressure points” (such as on the back of the head, ears, back of shoulders, elbows, buttocks, hips, heels, or any place a bony part rests on a surface) Red pressure
[cancer.org]