See this? It's called an inflatable "doughnut" and it sometimes is recommended for people to sit on to prevent pressure ulcers (BED SORES). However, it's now not recommended at all. In fact, a wound-care specialist doctor told me these should not be used, as they simply cause more pressure to occur on the coccyx area of the lower back! (So you'll really end up with more sores!)
Now, here's something you can use! It's a memory-foam mattress topper. I bought several at our local Target store. I used the double-bed size to cover his entire lift/recliner chair. I cut up a twin-size topper and use the pieces to rest his ankles, his elbows, under his knees, etc., when he goes to lie down.
They may look a bit odd, but they are working!
Another thing I can definitely recommend is the Medline Soothe and Cool paste with allantoin. It's been a really great barrier and it helps promote healing.