This prospective observational study aimed to determine the rate of success of reduction of dislocated hip prostheses using conscious sedation. In 101 consecutive patients presenting to the emergency department between August 2000 and February 2003 with a dislocated hip prosthesis, reduction was attempted using conscious sedation. The outcome measures of the study were (a) rate of success of the attempted reductions (b) rate of complication of the sedation or the procedure, and (c) rate of success in the three subgroups (based on degree of dislocation). The overall success rate was 62% (95% CI 53% to 71%). There were six complications: five related to sedation and one was a mild foot drop. The mean time to attempted reduction using conscious sedation was 1.83 hours and for an equivalent group who were excluded and subsequently required general anaesthesia the mean time was 10.9 hours. Reduction of isolated unilateral prosthetic hip dislocation using conscious sedation in the emergency department is safe and has a reasonable success rate. Prosthetic hip reduction can be attempted more quickly using conscious sedation than when awaiting general anaesthesia. R eduction of dislocated hip prostheses is usually performed under general anaesthesia. Often there are significant delays waiting for theatre and controlling patients' pain in the interim can be difficult. A comprehensive literature search failed to identify any studies whose primary outcome was the rate of success of reduction under sedation. A single case report 1 was found in which etomidate was used to facilitate reduction instead of ''narcotics''.An pilot study 2 conducted in our department (1998-99; unpublished) demonstrated a success rate of 67% was possible using conscious sedation. Our aim in the present study was to prospectively establish the rate of success, and the nature and frequency of complications when reducing prosthetic hip dislocations using conscious sedation. METHODSWe included adult patients presenting to the emergency department with an isolated, unilateral dislocation of a prosthetic hip between August 2000 and February 2003. Exclusion criteria were American Society of Anesthesiologists (ASA) score .2; neurovascular deficit; dislocation .12 hours; previous failure using sedation; inability to consent; refusal; only one doctor on duty or when it was considered ''too busy''.It has been the usual practice within our accident and emergency department to attempt reduction of dislocated hip prostheses under sedation for the previous 15 years. Since this study was an attempt to establish the rate of success and nature and frequency of complications, and it did not involve introduction of a new practice, ethical approval was not obtained.Patients' demographic details were recorded contemporaneously on a proforma and the patients were given intravenous morphine to control their pain. Patients were examined fully and specifically for any neurovascular deficit of the affected leg. All patients had an anteroposterior x ray of the hemipelvis. We...