Such a letter is a GREAT idea!

When I started having pain while running last year, I went to a new ortho doctor. I decided to try someone new because the ortho doctor who was treating my broken leg four years ago (a torsion fracture of my tibia from stepping in a hole after running out a parachute landing :-)) repeatedly just told me that I might not ever be 100% again. The first thing this new doctor did was ask "so tell me about your typical week, what do you do?" I told him about running and cycling and yoga. He asked how many hours of each. Instead of judging me by how I look or what my job is, he said "well, endurance athletes are sometimes the hardest to treat because all of you seem to run/ride right through the pain and aren't good at judging when to stop. I will make you a deal, I promise you that I will get you out there and up to normal activity levels as soon as I can if you promise me to be honest about your pain."

I was tickled pink that he called me an endurance athlete (and then I wondered why I didn't call myself that? I do 4 or 5 centuries each summer and a lot of longer rides as well).