The objective of this study is to compare Ketamine-Propofol with Ketamine-only in a double-blind, randomised, controlled trial in a paediatric emergency department. We believe that the combination of these two agents will provide a new and more effective option for procedural sedation in paediatric emergency department patients. The hypothesis of the study is that paediatric emergency department patients requiring procedural sedation for an isolated orthopaedic injury with Ketamine-Propofol will have reduced total sedation time, time to recovery, complications and improved satisfaction scores compared to patients receiving Ketamine alone.