Emergency. 2018; 6 (1): e15 OR I G I N A L RE S E A RC H The Accuracy of Ultrasonography in Detection of Ulnar Collateral Ligament of Thumb Injuries; a Cross-Sectional Study Babak Shekarchi1, Mohammadreza Mokhdanzadeh Dashti2, Mostafa Shahrezaei3, Ebrahim Karimi2∗ 1. Radiology Department, Imam Reza Hospital, AJA University of Medical Sciences, Faculty of Medicine, Tehran, Iran. 2. Emergency Department, Be’sat Hospital, AJA University of Medical Sciences, Faculty of Medicine, Tehran, Iran. 3. Orthopedics Department, Imam Reza Hospital, AJA University of Medical Sciences, Faculty of Medicine, Tehran, Iran. Received: January 2018; Accepted: February 2018; Published online: 19 February 2018 Abstract: Introduction: Timely diagnosis and treatment of traumatic injury to ulnar collateral ligament (UCL) of thumb is of special importance for preserving the full function of the hand. Therefore, the present study has been de- signed with the aim of evaluating the accuracy of ultrasonography in detection of these injuries. Methods: The present diagnostic accuracy study was performed on trauma patients over 15 years old who had clinical evidence of injury to UCL of thumb and were admitted to the emergency department. All patients were evaluated regard- ing injury to the mentioned ligament via ultrasonography and MRI and finally, the accuracy of ultrasonography in this regard was measured considering MRI as the reference test. Results: 20 individuals with the mean age of 38.60 ± 13.45 (16 – 64) years were evaluated (60% male). Based on ultrasonography and MRI findings 7 (35%) individuals and 7 (35%), respectively had complete ligament rupture (kappa: 0.560 (95% CI: 0.179 – 0.942)). Sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratio of ul- trasonography in detecting injuries of the mentioned ligament were 71.42 (30.25 – 94.88), 84.61 (53.66 – 97.28), 71.42 (30.25 – 94.88), 84.61 (53.66 – 97.28), 2.5 (0.71 – 8.82), and 0.18 (0.04 – 0.67), respectively. Conclusion: Based on the findings of the present study, performance of ultrasonography by a radiologist in the emergency department has 80% accuracy in detecting traumatic injuries of UCL of the thumb. Keywords: Ultrasonography; collateral ligament, ulnar; injuries; magnetic resonance imaging; dimensional measurement accuracy © Copyright (2018) Shahid Beheshti University of Medical Sciences Cite this article as: Shekarchi B, Mokhdanzadeh Dashti M, Shahrezaei M, Karimi E. The Accuracy of Ultrasonography in Detection of Ulnar Collateral Ligament of Thumb Injuries; a Cross-Sectional Study. Emergency. 2018; 6(1): e15. 1. Introduction U lnar collateral ligament (UCL) of thumb is one of the major protective ligaments of metacarpophalangeal joint (1). Damage to this ligament usually happens following hyper-abduction or hyper-extension of the men- tioned joint (2, 3). This injury is among the most common injuries of thumb with a frequency of 50 cases in 100000 pop- ulation each year, following accidents and trauma and sports injuries (2, 4-7). Rupture of this ligament leads to decrease in ∗Corresponding Author: Ebrahim Karimi; Emergency Department, Be’sat Hospital, Afsariyeh Highway, Hejrat Boulevard, Tehran, Iran. Email: ebrahimkarimi86@gmail.com Tel: +989124544838 the ability of the patient to hold objects and make a fist us- ing the thumb and therefore, timely diagnosis and treatment of this injury is very important for preserving the function of the hand (8, 9). Diagnosis of injury to this ligament is mostly based on clini- cal examination and inability to bear pressure on the thumb in the valgus position (10). Plain radiography, ultrasonog- raphy, and magnetic resonance imaging (MRI) are available imaging tools for evaluating UCL injuries of thumb. Plain ra- diography shows fractures properly and ultrasonography and MRI are good for showing the details of injury to soft tissue (11-13). Sensitivity and specificity of MRI in detection of UCL of thumb have been estimated as 100% in a study by Harper et al. (14). However, the accuracy of ultrasonography in de- tection of this type of injuries has varied from 40% to 92% This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: www.jemerg.com B. Shekarchi et al. 2 between various studies (15-18). Since ultrasonography has become an available and inexpensive tool in most emergency departments, there is an increasing inclination towards using ultrasonography in detection of various problems in patients. Therefore, the present study has been designed with the aim of evaluating the accuracy of ultrasonography in detection of traumatic injuries of UCL of thumb. 2. Methods 2.1. Study design and setting The present diagnostic accuracy study was performed on trauma patients who had clinical evidence of injury to UCL of thumb and were admitted to the emergency department of Be’sat Hospital, Tehran, Iran, over a period of 2 years. All the patients were evaluated regarding injury to the mentioned ligament via ultrasonography and then MRI and finally, the accuracy of ultrasonography in this regard was measured considering MRI as the reference test. Protocol of the present study was approved by the ethics committee of AJA Univer- sity of Medical Sciences and all researchers adhered to the principles of Helsinki Declaration. Before inclusion in the study, informed written consent for participation in the study was obtained from the patients or their companions. 2.2. Participants Participants of the present study consisted of patients over 15 years of age who had clinical evidence of traumatic injury to UCL of metacarpophalangeal joint of the thumb that were included via consecutive non-probability sampling. Those with non-traumatic injuries of UCL, visible fracture and rup- ture at the anatomic site under evaluation, and also those who did not cooperate in performing imaging were excluded from the study. No sex limitation was considered in the present study. 2.3. Imaging Ultrasonography of tendon was performed by a skilled radi- ologist using GE voluson E8 bt10 device and 12MHz linear probe of MSK system. In addition, MRI of the tendon was done using a 1.5 tesla device and from T1 view for anatom- ical interpretation and T2 view for pathological interpreta- tion. Injuries were reported as complete rupture, without rupture, and/or with minor rupture. The radiologist inter- preting MRI and the sonologist were not aware of each other’s findings and the clinical findings of the patient. 2.4. Data gathering Data gathering was done by a senior emergency medicine resident using a pre-designed checklist including demo- graphic data of the patients (age, sex, height, and weight) as well as ultrasonography and MRI findings regarding injury of UCL. In this study presence of tenderness at the time of per- forming Valgus Stress test and also Valgus Stress range more than 30 degrees (15-30 = normal) were considered as clinical evidence of probable injury of UCL (19). 2.5. Statistical Analysis Minimum sample size required for the present study, consid- ering 15% prevalence of UCL injury (20), 95% confidence in- terval, 0.17 precision and considering 15% probability of loss samples was estimated as 20 cases. Data underwent statisti- cal analysis using SPSS 21 statistical software. Data were pre- sented as frequency (%) or mean ± standard deviation. For calculating sensitivity, specificity, positive and negative pre- dictive value, positive and negative likelihood ratio, and ac- curacy of ultrasonography in detection of traumatic injuries of UCL with 95% confidence interval, Vassarstats medical calculator was used. In this study, MRI was considered as the reference test. For evaluating the agreement rate between the findings of ul- trasonography and MRI, calculation of kappa coefficient with 95% confidence interval was applied. In this study, kappa coefficient less than 0.20 was considered as little agreement, 0.21 – 0.40 as poor, 0.41 – 0.60 as average, 0.61 – 0.80 as good and 0.81 – 1.00 as very good. 3. Results 20 individuals with the mean age of 38.60 ± 13.45 (16 – 64) years were evaluated (60% male). Table 1 depicts the baseline characteristics of the studied patients. Most patients were in the 30 – 45 years age group (45%). Mean body mass index (BMI) of the patients was 22.95 ± 3.02. Based on ultrasonography findings 7 (35%) individuals had complete rupture of UCL of thumb and others had minor ruptures or no rupture at all. Based on MRI findings, these rates were 7 (35%) individuals with complete rupture, and 13 (65%) patients without or with minor injuries. Agreement rate between the findings of ultrasonography and MRI based on calculation of kappa coefficient was 0.560 (95% CI: 0.179 – 0.942). Table 2 shows the screening performance characteris- tics of ultrasonography in detecting injuries of UCL of thumb in comparison with MRI. The overall accuracy of ultrasonog- raphy in the mentioned field was estimated as 0.80 (95%CI: 65.34 – 94.27). 4. Discussion Based on the results of the present study, performance of ul- trasonography by a radiologist in the emergency department has 80% accuracy in detecting traumatic injuries of UCL of the thumb. Rate of agreement between the findings of ultra- sonography and MRI in this regard was estimated as average. It seems than considering its relatively low sensitivity, ultra- This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: www.jemerg.com 3 Emergency. 2018; 6 (1): e15 Table 1: Baseline characteristics of the studied patients Variable Values Sex Male 12 (60) Female 8 (40) Age (year) < 30 5 (25) 30 – 45 9 (45) ≥ 45 6 (30) Body mass index 18.5 – 25 12 (60) ≥ 25 8 (40) Height (m) 1.76 ± 0.07 Weight (kg) 77.5 ± 11.9 Data are presented as mean ± standard deviation or fre- quency and percentage. Table 2: Screening performance characteristics of ultrasonography in detection of traumatic injuries of ulnar collateral ligament of the thumb in comparison with MRI Characteristics Values (95% CI) True positive 5 False positive 2 True negative 11 False negative 2 Sensitivity 71.42 (30.25 – 94.88) Specificity 84.61 (53.66 – 97.28) Positive predictive value 71.42 (30.25 – 94.88) Negative predictive value 84.61 (53.66 – 97.28) Positive likelihood ratio 2.5 (0.71 – 8.82) Negative likelihood ratio 0.18 (0.04 – 0.67) sonography cannot yet be used as a proper screening tool in detecting injuries of UCL of thumb. Sensitivity and specificity of MRI in detecting injuries of UCL of thumb in various studies have been estimated as 96% to 100%, and 100%, respectively and it is currently considered as the standard test in detection of these injuries (14, 15, 21). Of course, detection of tendon injuries using MRI has its own complications and requires skill of the interpreter. Despite ultrasonography being available, portable, and costing less, it also depends on the operator and therefore, its accuracy varies widely and has been reported as 40% to 92% in differ- ent studies (17, 18, 22). In a study by Melville et al. in 2013 sensitivity and specificity of ultrasonography method were estimated to be about 100% (23). In contrast, Papandrea et al. in 2008 estimated sensi- tivity and specificity of ultrasonography to be 76% and 81%, respectively. In addition, the positive and negative predictive values of ultrasonography were estimated to be 74% and 87%, respectively, in the mentioned study (16). The results of the present study are in agreement with the studies performed in this regard to a great extent. In this study, attempts were made to eliminate limitations such as training and insufficient skill of the operator by ask- ing a radiologist to perform the ultrasonography. But despite the performance of ultrasonography by a radiologist, the number of false positive and false negative cases or in other words incorrect report was relatively significant (4 cases out of 20 reports or 20%). The first studies carried out in the field of assessing the di- agnostic accuracy of ultrasonography in detecting ULC of thumb injuries belong to 1980 to 2000. Maybe the reason for ultrasonography not being known as a proper method for widespread use in this regard is that first, the mentioned problem is not a life-threatening emergency and suspected cases in clinical examination will not undergo further inter- ventions and following fixation, will be visited by an orthope- dic specialist or a surgeon with delay. Second, since a radiol- ogist is not available at all times of the day, even if the accu- racy of this method is high it will not be available 24 hours a day. In addition, if emergency medicine specialists gain the required skill in this regard by undergoing special train- ings, surgeons and orthopedic specialists will not rely on it for planning surgery and will apply more accurate methods such as MRI. Therefore, despite the numerous advantages of bedside ultrasonography in the emergency department, we should be cautious about its type of application and exagger- ation of its abilities. The wide confidence interval of likeli- hood ratio of ultrasonography in detection of the mentioned tendon’s injuries challenges it as a proper screening test. It seems that in the presence of a low-risk and accurate method such as MRI, performing ultrasonography cannot be of much help in management of these patients and accurate planning regarding their need for repair. 5. Limitation Small sample size might be the most important limitation in generalizing the findings. In this study by blinding the so- nologist and MRI interpreter to the clinical data, we tried to prevent any bias in this regard. 6. Conclusion Based on the findings of the present study, performance of ultrasonography by a radiologist in the emergency depart- ment has 80% accuracy in detecting traumatic injuries of UCL of the thumb. Rate of agreement between the findings of ultrasonography and MRI in this regard was estimated as average. It seems than considering its relatively low sensitiv- ity, ultrasonography cannot yet be used as a proper screening tool in detecting injuries of UCL of thumb. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: www.jemerg.com B. Shekarchi et al. 4 7. Appendix 7.1. Acknowledgements All the staff members of the emergency department of Be’sat Hospital are thanked for their cooperation throughout the study period. 7.2. 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