I've never had any experience with serious medical injuries thus far (knock on wood) but this happened to my dad last year. He's 60, by the way. Two summers ago he was backing his truck up to a 28ish foot travel trailer and stopped about three inches too short. He was already in a bad mood so instead of getting back in and backing up the rest of the way, he decided to just pick the thing up and hoss it on there. He said it only hurt slightly at the time but about a year later he had to have surgery.
AFAIK its not bothering him anymore.