Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In medicine, the Ottawa ankle rules are a set of guidelines for doctors to aid them in deciding if a patient with foot or ankle pain should be offered X-rays to diagnose a possible bone fracture. Before the introduction of the rules most patients with ankle injuries would have been X-rayed. However only about 15% of X-rays were positive for fracture, other patients had sprains or other injuries. As a result many unnecessary X-rays were taken, which was costly, time consuming and a possible health risk.