"I hope airport security is a bit better."
It isn't! I have had both knees replaced and have cards from my orthopedic surgeon, as well. I had them in hand when going through security. I set off the alarm. When I tried to show the agents the cards, but they didn't even look at them, just showed me to the "wanding area". I was wanded and patted down. Guess I passed -- they let me continue through.
At least they did give you a closer check. I could have been armed to the teeth.