There's this woo-woo stuff about the "Power of Intention," but i would say this is a good demonstration of a coordinated effort of body and mind.
I also have rheumatic arthritis, though nowhere nearly as bad as described, because I only walk with a stick in the rare periods when symptoms are worst. When I was informed of the aspects of this condition, I was told that some people live without noticing that their cartilage has gone, whereas others get in pain when there is still cartilage left. I was also told that the cartilage in rare cases, and only in young people, can be regenerated.
On the picture I see a young person.