If an employee claims a work related back injury it is almost impossible to prove it didn’t happen. He stays out of the spotlight for two years, come back and within six months claims a second back injury and is out another two years.
I saw it several times in my industrial days. Everyone knew he could work, but couldn’t do anything about it.
I injured my already bad knees but if I was smart like another person I know I should have claimed it happened at work...