Moral of the story: Only train with reserved, quiet, discrete people who do their best not to upset the hospital staff.
I.e., don't train with Texans...
About eight (good grief has it been that long...) years ago I snapped my ulna in half during randori at the end of class (my fault, drove home the point that te-gatana is a metaphor not a reality). A dojo mate splinted it with two wooden tanto, she was a medical professional so she did me up right. I didn't bother changing out but headed to the hospital with her. Got there and finally got to talk to a doctor. "Well I was going to ask how this happened, but I'm guessing you weren't at a pajama party..." he says. After complimenting my friend on the splint (she was an EMT for a while) he started unwrapping it. When he got to the tanto, he paused, and slowly handed them to my friend, "I bet you want these back..."
I also cut the front of my knee about 10 years ago doing kiri otoshi tameshigiri. I was paying attention to the cut and not my footwork and cut in a hanmi (a no-no in my battojutsu style). I over cut, and went clean through the target and wacked the front of my knee with the tsuba. I looked down and there was about a 1.5" slice in my hakama. I pulled it up and there was a matching 1.5" slice in my dogi pants. I pulled my dogi pants up and there was another matching 1.5" scalpel clean slice right across the top of my knee. I ran inside and put two butterflies across the cut. The cut was so clean that it healed up in three days with no stitches.
Those things be crazy sharp.