Joe, I don't know about there being exceptions for medical circumstances. Last year we visited our son in Canada, and had to change planes at LAX coming and going. While in Canada I suffered (and how!) a fall, broke my left arm and sprained my right wrist. My broken arm was put in a slab cast which is rigid plaster along the top and bottom length of my arm but not at the sides, the whole thing wrapped in firm bandages. When going through security at LAX coming home, I was asked to remover the bandages and cast - "I can't, it's broken", I replied. I had doctors' reports with me and was prepared to take it further if necessary, but my reply was accepted. However I had to remove and replace my jacket although it had no metal fastenings, and of course my shoes (slip-ons, not laced), with no help - not easy without a functioning wrist! The drug detecting tape was rubbed along the edges of my plaster cast and I chose to be patted down rather than go through the body scanner, because I had x-rays when I broke my arm and faced the prospect of more as it healed so I didn't want any unnecessary radiation. The treatment I received was firm, not rude but not particularly friendly either.

Cheers
JennieG