If you all haven’t figured out yet, I love clinical decision instruments. Taking clinical variables and applying them the to validated statistical studies to estimate pretest probability and predict clinically significant injuries is a large part of emergency medicine. We have a lot of patients walk through the doors in the emergency department and if we ordered everything on everyone, the cost to the medical system would skyrocket and the wait times would be awful. So for this episode, I want to review the Ottawa Rules of foot/ankle, knee, c-spine, head, and subarachnoid hemorrhage. If you are not using these in your practice, you should.