Objectives and Backgrounds: Ankle injuries account for 8% of all minor injuries attending EDs in the UK. The Ottawa ankle rules (OARs) were introduced to assess the need for x-ray in the 1990s (Stiell et al 1992). Although they are said to have reduced the number of ankle x-rays requested many unnecessary ankle x-rays are still taken, and although the sensitivity of the OARs 95–100% the specificity is consistently low. A vibrating tuning fork has been shown to increase the specificity of the OARs while maintaining the high sensitivity on a pilot study on simple twisting ankle injuries and resulted in a 66% reduction in the number of ankle x-rays requested (Dissman and Han 2006). However, this study had a strict inclusion criteria and the tuning fork test was carried out by a single-operator, reducing the generalisability of the results. This study aims to assess whether the tuning fork test can increase the diagnostic accuracy of the OARs when used on twisting ankle injuries by multiple operators in multiple emergency care settings. Methods: A two part multi-site study was undertaken across three EDs in within Hampshire UK. The first part of the study consisted of a diagnostic test using the tuning fork test on patients already known to be OARs positive and therefore due to receive an x-ray of their ankle. Patients were invited to take part if they were aged 12 years or over and had injured their ankle as a result of a simple twisting mechanism. Patients were excluded if there was obvious deformity to the ankle. After assessing for bony tenderness a vibrating tuning fork was placed at the site of maximal tenderness and 6 cm proximal to this site. In order to form a control group the patient's uninjured ankle was also assessed with the tuning fork. Patient's were randomised as to which ankle was assessed with the tuning fork first. The results of the tuning fork test and the x-ray (which was interpreted blind of the tuning fork test) were compared and the number of times they agreed and disagreed recorded. The second part of the test included a series of focus groups where participants and clinicians involved in the study were asked about their views on the use of the tuning fork test in clinical practice. Data were analysed using thematic analysis. A total of 1300 participants were required in order to detect a specificity of 95% (±3%) with a 95% CI where the injury under test had a prevalence in the population of 15%. The study was funded by the CCF Research for Patient Benefit scheme, and sponsored by the Portsmouth Hospitals NHS Trust. Southampton and SW Hampshire (A) ethics committee approved the study. Results: Patients have been recruited into the study since June 2009. Part 1 of the study is still in progress, but as of 21st April 2011 a total of 1245 participants have been recruited. The data has not yet been analysed but this is expected to take place during June 2011. The data collection phase of part 2 of the study is complete and although full analysis of the data is yet to take place provisional analysis of the qualitative data using thematic analysis identifies that patients accept the use of the tuning fork test. Patients stated they were intrigued when the use of the tuning fork was first discussed with them. Patients also rated spending less time in the ED as more important than receiving an x-ray, which is in contrast to the clinicians who claimed that the majority of patients expect an x-ray for their ankle injury. As well as reducing exposure to radiation saving the NHS money by reducing unnecessary x-rays was one of the main advantages raised by patients. Conclusions: The results of the study are yet to be fully analysed. However it is anticipated that the tuning fork test will improve the diagnostic accuracy of the OARs when used on simple twisting ankle injuries. The tuning fork test is quick and easy to learn and initial analysis of the qualitative data reveals that it's use would be accepted by patients and clinicians alike. This presentation outlines independent research commissioned by the National Institute for Health Research (NIHR) under its RfPB Programme (Grant Reference PB-PG-1207-15022).