I am obsessed with Lynn’s skin. Many years ago I worked as a home health nurse and I saw some terrible bed sores that started out small and then progressed to craters. Some of the patients had their entire backsides destroyed. Most of the breakdown, I expect, was due to inattention but some was also due to poor nutrition and just the disease process the person had.
With progressive MS, secondary or primary, the person often is in a wheelchair or in bed most of the time. In either situation, the person’s ability to shift their position is very limited or maybe non-existent.