what about elbows.
We had a guest from another dojo came by...and I injured my elbow. took a few days to heal, but I can move it again without the sharp pain.
The dude was amazing (amazingly rough). When he was doing a version of sankyo he would take my arm, shake, twist, pin, etc. and my elbow literally could not take anymore.
The sempai was away that day, and a 3rd kyu (police officer) was showing some rougher police techniques.
My lesson...people from other dojos are dangerous.