Comparison of the ottawa ankle rules to ankle ultrasound imaging in the decision making process for the indication of radiographic imaging of the ankle

Comparison of the Ottawa Ankle Rules to Ankle Ultrasound Imaging In The Decision Making Process For The Indication Of Radiographic Imaging Of The Ankle Objective: Ankle traumas account for a major proportion of emergency department admissions. In the United States, 28,000 emergency department presentations with ankle traumas have been recorded per day. 15% of the ankle trauma cases presenting to the emergency department services are diagnosed with fractures, which suggests that not all ankle traumas require radiographic imaging. To determine which cases will require ankle X-Rays, Ottowa ankle rules (OAR) provide instructions in line with the current literature. However, due to the high sensitivity and lower specificity of OAR, the requirement for other methods is a current issue. Ultrasound (US) is non-invasive, portable, less costly, and hazardless, therefore, it is suggested as a diagnostic tool for the evaluation of bone structures in many studies. In our study, it was aimed to compare the OAR and US imaging in predicting the presence of fractures and to determine the diagnostic value of the US in ankle fractures. Material and Method: A total of 285 female and male patients older than 18 years old, who presented with ankle traumas to the emergency department of Ege University Medical Faculty 13 between September 2017 and March 2018, were studied. At the initial physical examination, which was performed by the emergency department resident, OAR was questioned. US imaging of the ankle was performed for all patients who signed the consent forms to participate the study. The assessments of the US images were performed by an investigator team consisting of 5 senior residents of emergency department with more than 2 years of residency period and who provided good and outstanding agreements with the US supervisor/trainer, the emergency care specialist, and the author investigator prior to the study. The investigations were performed with Sonosite-Fujifilm portable ultrasound 6-13M Hz linear probe. X-ray images were obtained from all patients in the study regardless of the OAR and US findings. An emergency care consultant orthopedist, who was uninformed of any of the findings, evaluated the patients and made the final diagnosis. All findings were recorded in the case report forms and the data were compared using appropriate statistical methods. Results: A comprehensive analysis has been performed evaluating the findings of OAR, US, and X-ray from 285 patients presenting with ankle traumas and complying with the study criteria. In this study, which we aimed to investigate the reliability of OAR in decision making to obtain X-rays, the positive predictive value (PPV) was remarkably low despite the high negative predictive value (NPV) (27.9% and 100% respectively). In order to determine the fractures, the ankle US of the study patients were performed by 5 different investigators, yielding a PPV of 94.0% and an NPV of 94.5%. In terms of specificity, US imaging was superior to OAR in determining the fractures (p= 0.036). 14 Ankle X-Rays were obtained from all patients and yielded a 96.0% sensitivity and 97.6% specificity in determining the ankle fractures, representing similar limitations with the literature. When these findings were compared with the US, the specificity of US was found to be higher, whereas its sensitivity was lower (84.0%, 98.1%, 96.0%, 97.6% respectively). The kappa value was 0.850 for US and X-Ray in determining the fractures and this value was evaluated to indicate a good concordance. No statistical differences were found when the age and gender of the study patients were compared in terms of making a diagnosis with the US imaging. In our study, the ligament injuries, which are not diagnosed with X-Ray images, were evaluated, too, and ATFL injuries were detected at a rate of 12.4%, consistent with the reports in the literature. The specificity of US was 97.6% and consistent with the literature in making the diagnosis of ligament injuries. Conclusion: OAR can be applied before radiological imaging in ankle traumas and allows investigation findings with high sensitivity. The screening of the ankle trauma patients with OAR and US can be a method to be employed to prevent unrequired X-ray imaging. US alone is superior to OAR in this respect. Being a noninvasive, portable and radiation-free procedure, US allows repeat investigations and therefore can be used in diagnosing the missed fracture cases. Diagnoses made with US images do not demonstrate any differences in terms of gender or age. The US examinations of the ankle can be used reliably in making the diagnosis and the treatment of fractures. 15 Making the diagnosis of soft tissue and ligament injuries is possible with US in patients with ankle traumas, however, further studies are required in determining their reliability particularly in detecting the ligament injuries.