Apparently this is how they make sure they operate on the correct body part.
That struck me as both reassuring and unnerving. On the one hand, it was reassuring to know I wouldn’t wake up to discover a missing testicle. But on the other hand, it was unnerving to realize I had placed my fate in the hands of a medical system that has to resort to felt-tip markers in order to prevent surgical mistakes.
In the end, of course, they operated on the right knee, and I’m happy to report that I’m healing nicely.
PS: Sadly, even writing on the correct body part sometimes fails.