Just got an info sheet from the pain management clinic I use for PRP when I need it.
There seems to be a theory forming that arthritis pain is actually from nerves in subchondral bone getting really cranky from pressure thru bone-on-bone contact or thru defects in cartilage. This might be why some people are in severe pain without much to be seen on x-ray, and others have completely awful x-rays and not much pain.
Wondering if this might be why PEMF works for arthritis pain. It would be about the only thing that could get thru the bone to those nerves.