This disorder is called Fibrodysplasia ossificans progressiva, or FOP. It causes tissue when damaged to regrow as bone
This rare disorder is not fatal, yet most people having this die young, starving to death after their jaws freeze shut or suffocating when new bone develops, making it impossible to breathe. Most people are bedridden at only 20 y/o and normally only live til 40 y/o. Sadly there is NO cure.
I hope this helped you and have a good day dear <3