Back in the days when I worked in the ER, I ordered a lot of unnecessary x-rays. Ankle x-rays were a particular problem. Often I was sure that there was no fracture, but I ordered the x-ray anyway because of habit–patients with injured ankles got an x-ray. That’s just the way it was.
So I loved the Ottawa Ankle Rules when they came out. The Ottawa Ankle Rules were developed by a group of doctors in (where else?) Ottawa to determine which ankle injuries did NOT need to be x-rayed. They have been studied many times and have been found to be accurate. When used, Ankle Rules can cut the number of ankle x-rays by a third, easy.
The Ottawa Ankle Rules can be even more important in corrections than in the ER. There, the only downsides to an unnecessary x-ray were expense and time. But in corrections, x-rays can be a logistical and security nightmare. So it is good to know when you don’t have to order an x-ray for the inmate who twisted his ankle attempting to dunk the basketball at rec.