Archives of Academic Emergency Medicine. 2019; 7 (1): e49 OR I G I N A L RE S E A RC H Diagnostic Accuracy of Ultrasonography in Diagnosis of Metatarsal Bone Fracture; a Cross Sectional Study Mohsen Ebrahimi1, Seyed Reza Habibzadeh1, Sayyed Reza Ahmadi1, Samaneh Khajeh Nasiri2, Mohammad Majid Kaveh1, Mahdi Foroughian1∗ 1. Department of Emergency Medicine, Faculty of Medicine, Mashhad University of Medical sciences, Mashhad, Iran. 2. Department of Radiology, Faculty of Medicine, Mashhad University of Medical sciences, Mashhad, Iran. Received: May 2019; Accepted: July 2019; Published online: 17 August 2019 Abstract: Introduction: Metatarsus is one of the most common sites in the sole of foot bones fractures. The aim of this study was to determine the diagnostic accuracy of ultrasound in diagnosis of metatarsal bone fractures fol- lowing foot trauma. Methods: This cross-sectional study was carried out on patients with blunt foot trauma admitted to emergency department of a hospital in Mashhad, Iran from January to September 2016. All patients were evaluated with bedside ultrasound for the presence of first to fifth metatarsal fractures and screening per- formance characteristics of ultrasonography in detection of metatarsal fractures were calculated considering foot radiography as the reference test. Results: The study was conducted on 102 patients with a mean age of 35.14±14.32 years (56.8% male). The most common signs of trauma in physical examination were pain and ten- derness (100%), swelling (96.1%), ecchymosis (14.7%) and deformity (1.9%). Sensitivity, specificity, and positive and negative likelihood ratio of ultrasonography in detection of metatarsal bone fracture were 96.7% (95% CI: 0.83-0.99), 84.5% (95% CI: 0.73-0.92), 73.1% (95% CI: 0.57-0.85), and 98.3% (95% CI: 0.91-0.99), respectively. The overall accuracy of ultrasonography was 0.906 (95% CI: 0.844 – 0.969) based on area under the receiver operating characteristic (ROC) curve. Conclusion: Considering the excellent diagnostic accuracy, ultrasonography can be used as an alternative means in diagnosis of metatarsal bone fractures. Keywords: Ultrasonography; radiography; fractures, bone; metatarsal bones Cite this article as: Ebrahimi M, Habibzadeh S R, Ahmadi S R, Khajeh Nasiri S, Kaveh M M, Foroughian M. Diagnostic Accuracy of Ultra- sonography in Diagnosis of Metatarsal Bone Fracture; a Cross Sectional Study. Arch Acad Emerg Med. 2019; 7(1): e49. 1. Introduction Foot and ankle are areas of the body that are most com- monly exposed to trauma (1, 2). Foot injuries account for about 25% of musculoskeletal injuries leading to emergency department visits (3). Although such injuries usually are not considered life threatening, but the function of involved or- gans could be at risk. Therefore, correct and rapid diagnosis of these injuries as well as early treatment can prevent long- term and short-term complications (4, 5). On the other hand, it should be noted that accurate diagnosis of injuries to the foot bones, particularly metatarsal injuries, is not possible with physical examination alone and imaging procedures al- ways have got a foothold, at least to rule out metatarsal frac- ∗Corresponding Author: Mahdi Foroughian; Department of Emergency Medicine, Faculty of Medicine, Mashhad University of Medical sciences, Mash- had, Iran. Tel: 05138525312, Email: foroughianmh@mums.ac.ir tures, as one of the most important clinical decisions (6, 7). Over time, the use of ultrasound (US) imaging has grown due to its low cost and lack of harmful radiation and good capa- bility to check the soft tissue and its importance in diagno- sis of foot and ankle injuries has increased (8). Some studies have evaluated the use of ultrasound in emergency depart- ments for assessing the existence of foreign bodies (9) as well as examining the skeletal structures in many rheumatic dis- eases (10). Since US is considered as a method of dynamic measurements, it accurately detects the smallest changes in the anatomical structure of body and is very useful in pa- tients with no specific clinical symptoms (3, 6, 11). To date, foot and ankle trauma is one of the most common indica- tions in ultrasound assessment. In addition, patients usually cooperate for ultrasound (8, 12). On the other hand, because the same physician who examined the patient performs the ultrasound, it also provides more rapid diagnosis; since the doctor can easily match up findings of history taking with imaging and reach the best diagnosis. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem M. Ebrahimi et al. 2 In studies that have been conducted recently, the accuracy of the US in diagnosis of foot and ankle injuries has been reported as very good and the results have increased will- ingness to do further investigations (3, 5, 6, 9, 13). How- ever, these small studies have indicated that the use of US could be helpful as much as plain radiography in diagnosis of metatarsal fractures. Based on above-mentioned points, the aim of this study was to determine the diagnostic value of ultrasound in diagnosis of metatarsal bone fracture in pa- tients referring to the emergency department due to foot and ankle blunt trauma. 2. Methods 2.1. Study design and setting This cross-sectional study was carried out on patients admit- ted to emergency department of Edalatian Hospital, Mash- had, Iran, from January to September 2016, following foot trauma. All patients underwent ultrasonography and radiog- raphy of foot and diagnostic accuracy of ultrasonography in detection of metatarsal bone fractures was measured. This study was approved by the ethics committee of Mashhad University of Medical Sciences, Iran (Code: 931645). In addi- tion, all items expressed in the Declaration of Helsinki were taken into account. The patients filled the written consent form for enrollment in the study. Given that our study was an observational one, there was no threat to patients for thera- peutic research efforts; however, the researchers supported all patients during the study in case of any complication. 2.2. Participants All conscious cases over 16 years old with stable hemody- namics and clinical indication for foot radiographic exami- nation were enrolled to the study. Lack of patient consent, penetrating trauma, open fracture or dislocation, and the presence of osteomyelitis or chronic skeletal problems were among the exclusion criteria. 2.3. Data gathering Basic information, including age, gender and type of trauma (penetrating or blunt) was recorded for patients. Then, the emergency medicine specialist performed bedside ul- trasound for all patients and ultrasonography findings re- garding presence or absence of metatarsal bone fractures were recorded. Then, all patients underwent foot radiogra- phy (posterior-anterior and oblique views). The emergency medicine specialist, faculty member with board certificate, interpreted radiographic findings. In addition, a radiologist as a project colleague interpreted all radiographs. The radio- graphic findings were recorded as the presence or absence of fractures. The emergency medicine specialist was unaware of radiographic findings when doing the ultrasound and the radiologist was also blind to the sonographic findings. The emergency medicine resident was responsible for data gath- ering. In this study, the samples were selected by nonrandom purposive sampling method. All sonographies were performed according to Ankle Ultra- sound Technical Guidelines of European Society of Muscu- loskeletal Radiology, using ultrasound device (manufactured by Honda-Japan) and 10 MHz linear probe. In addition, the bone structures that should have been evaluated by ultra- sound were prepared in a checklist in advance for specialists to assess the items based on the checklist. The bone checklist included first to fifth metatarsals. The fracture diagnosis cri- teria in ultrasound were the presence of cortical disruption or stepping or axial deviation of the bone surface. 2.4. Statistical Analysis Given the 60% prevalence of metatarsal bone fractures and 87.3% sensitivity reported in the study by Atilla in 2014 (13), as well as taking into account the type I error of 0.05, L=0.06, the sample size was calculated as 72. Considering a 20% dropout rate, the final sample size was 90 patients. All data obtained from the patients were entered into the computer and statistically analyzed using SPSS 17.0 for Windows (SSPS Inc., Chicago, IL, USA). Given the normal distribution of data, quantitative data were expressed as mean and standard de- viation. The sensitivity, specificity, positive predictive value (PPV ), negative predictive value (NPV ), positive likelihood ratio (PLR), and negative likelihood ratio (NLR) of sonogra- phy in detection of metatarsal bone fractures were calculated with 95% confidence interval (CI) using the Medcalc version 16.1 software. P<0.05 was considered statistically significant. 3. Results 3.1. Baseline characteristics of participants The study was conducted on 102 patients with a mean age of 35.14±14.32 years (56.8% male). The trauma had happened during everyday life in 63 (61.8%) patients, due to accident in 27 (26.5%) patients, and during exercise in 12 (11.8%) pa- tients. The most common signs of trauma in physical exam- ination were pain and tenderness (100%), swelling (96.1%), ecchymosis (14.7%) and deformity (1.9%). The mentioned signs were frequently detected in fore-foot (> 70%). 3.2. Diagnostic measures The prevalence of metatarsal fracture was 30.3% (n=31) based on radiographic findings and 40.1% (n=41) accord- ing to sonographic results. Overall, the ultrasound did not detect the fracture for one patient (medial side of the fifth metatarsal). In Addition; 11 (27%) suspected fractures on ul- trasonography were not confirmed by radiography. The sen- sitivity, specificity, PPV, NPV, PLR, and NLR of ultrasonogra- This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem 3 Archives of Academic Emergency Medicine. 2019; 7 (1): e49 Figure 1: Area under the receiver operating characteristic (ROC) curve of ultrasonography in detection of metatarsal bone fracture. phy in detection of metatarsal bone fracture were 96.7% (95% CI: 0.83-0.99), 84.5% (95% CI: 0.73-0.92), 73.1% (95% CI: 0.57- 0.85), 98.3% (95% CI: 0.91-0.99), 6.25 (95%CI: 3.61-10.79), and 0.04 (95%CI: 0.01-0.26), respectively. The overall accuracy of ultrasonography based on area under the receiver operating characteristic (ROC) curve was 0.906 (95% CI: 0.844 – 0.969, figure 1). 4. Discussion The results showed that ultrasound has remarkable sensitiv- ity and specificity compared to radiography and can be used in a shorter time than radiography in emergency situations for diagnosis of metatarsal bone fractures. The use of ultrasound for diagnosis of fractures by emergency physicians is more important when the priority is deciding within the shortest possible time, especially when the radio- graphy ward is overcrowded and there is the need to speed up the triage of patients to properly manage the emergency department. In addition, sometimes a doctor has high clini- cal suspicion to the existence of concurrent soft tissue dam- ages in patients admitted to the emergency department. In these cases, due to higher power of ultrasound in diagnosis of soft tissue injuries compared to radiography, using ultra- sound can be a priority in diagnosis. In order to use ultrasound in diagnosis of fractures in the emergency department, knowing the diagnostic power of ul- trasound for observing the fractures is important. This is- sue is something that very few studies have examined as many articles related to the use of ultrasound in diagnosis of metatarsal fractures are case reports (4-8, 11, 12). Preliminary results of this study confirmed that ultrasound was a powerful tool in triage of patients referring to the emer- gency department with suspected metatarsal bone fracture; this result is consistent with two other studies in this regard. In a study by Ekinci et al. (14) sensitivity, specificity, posi- tive predictive value and negative predictive value of ultra- sound in diagnosis of metatarsal fractures were reported as 100%, 99.1%, 95.2% and 100%, respectively. In a study by Canagasabey et al. (2) sensitivity, specificity, positive predic- tive value and negative predictive value of ultrasound in diag- nosis of fractures were found to be 90.9%, 90.9%, 52.5% and 98.9%, respectively. The sensitivity was over 90% and speci- ficity was over 85% in both studies, similar to our research. High sensitivity and specificity are two important features in determining the power of a diagnostic tool; hence, ultra- sound seems to be a powerful tool in diagnosis of fractures. PPV was reported as 73% and NPV was 100% with upward approximation. High negative predictive value of ultrasound may be the most important parameter confirming the diag- nostic value of ultrasound; because if ultrasound is negative, the presence of fracture can be ruled out, leading to better triage of the patients. However, since PPV and NPV are related to incidence rate of the disease in the study population and fracture prevalence rates are different among various studies, likelihood ratio, which is not under influence of disease prevalence, is used for comparison. In the present study, PLR and NLR were re- ported as 6.25 and 0.04, respectively, indicating the high di- agnostic value of ultrasonography. It seems that the high diagnostic value of ultrasound in diag- nosis of metatarsal fractures can be attributed to the dynam- ics of ultrasonography and the ability of the operator to cre- ate images in different sections. It should be noted that the reason for slight differences between the results of the cur- rent and other studies regarding sensitivity, specificity and other parameters of diagnostic power could be due to differ- ences in sample size, different quality of ultrasound devices used, experience and academic ability of ultrasound opera- tors. Importantly, about 4% of patients in our study were preg- nant, which highlights the importance of using x-ray- independent methods to diagnose fractures. Moreover, since the physician responsible for the ultrasound can press the probe when performing ultrasound examination, fractures with bone dynamic movements are more easily detected during ultrasound, and the pressure mentioned in previous studies will not be accompanied with unbearable pain for pa- tients (3). The gold standard for assessment of fracture in this study was radiographic findings interpreted by the radiologist. This cri- This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem M. Ebrahimi et al. 4 terion was chosen because plain radiography is performed in almost all patients with suspected fractured foot trauma. Se- lection of CT scan as the standard criterion would impose ex- cessive and sometimes unnecessary radiation on the patients and MRI was associated with high and unnecessary time and cost. 5. Conclusion According to the results of the present study, ultrasound has high sensitivity, high specificity, negative predictive value of about 100%, and favorable likelihood ratios in diagnosis of metatarsal fractures. Therefore, it seems that use of ultra- sound can serve as a very good alternative to radiography in diagnosis of metatarsal fractures. 6. Appendix 6.1. Acknowledgements None. 6.2. Author contribution Ebrahimi, Habibzadeh, Nasiri, Foroughian Study conception and design: Ebrahimi, Habibzadeh Acquisition of data: Kaveh Analysis and interpretation of data: Ahmadi, Foroughian Drafting of manuscript: Nasiri Critical revision: Foroughian Authors ORCIDs Mohsen Ebrahimi: 0000-0003-2168-8476 Seyed Reza Habibzadeh: 0000-0003-4569-1776 Sayyed Reza Ahmadi: 0000-0003-4921-976X Samaneh Khajeh Nasiri: 0000-0002-8228-6633 Mahdi Foroughian: 0000-0002-3944-9361 6.3. Funding/Support The study was financially supported by Mashhad University of medical sciences. 6.4. Conflict of interest The authors do not have any conflict of interest to declare. References 1. English E. Fractures and soft tissue injuries of the feet and ankle. Canadian family physician Medecin de famille canadien. 1985 Mar;31:585-90. PubMed PMID: 21274230. Pubmed Central PMCID: PMC2327960. Epub 1985/03/01. eng. 2. Canagasabey MD, Callaghan MJ, Carley S. 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