David and Don,
Come to think of it, I maybe be able to top your "sprain and break from seiza" stories --
Years ago, I broke my leg in seiza -- the left fibula -- while goofing around after class with another student. We were practicing some stuff in seiza, and in the process I got tossed over backward. My leg was levered at a diagonal beneath me and snapped. I heard and felt the "pop" and thought, "So that's what it sounds like when you break something."
I got a piggy-back lift to my truck, drove home (manual transmission) and had to wait until after Thanksgiving weekend to get the bone set.