 Recruitment Orthopaedic surgical teams, anaesthetists and theatre staff were made aware of the study that was being conducted at the investigators institution. Prospective subjects that met the inclusion criteria were identified from the hospital operating theatres database two weeks prior to surgery. A letter, which contained the studys objectives and methods, was sent out to all patients. Subsequently, a telephone call was made to patients one week before surgery to clarify any queries they had. Consent was obtained on the morning of surgery. All study participants provided written informed consent. 