Children frequently present to the emergency department with forearm injuries and often have an x-ray to assess if there is a fracture. Bedside ultrasound is a test that emergency practitioners can use to rapidly diagnose a fracture at the time of examination, without exposing children to ionising radiation. This trial will assess whether an x-ray is unnecessary when there is either a buckle fracture or no fracture seen on a portable ultrasound machine. We will also determine the time and cost implications of this new approach, which could enable families to go home earlier and could be more cost-effective, with less x-rays being ordered.