after a bone is crushed or whatever and is of no use , it is replaced by a titanium bone but how is this new bone connected to the muscles ?? (without that you wouldn't be able to move the bone and it will still be useless)

I'm going to direct you to a friend's page who has been doing a lot of research around this because it directly affects him. He is very happy to talk to people so go ahead and get in touch if you have additional questions:
https://www.gofundme.com/titaniumjames