Archives of Academic Emergency Medicine. 2022; 10(1): e47 OR I G I N A L RE S E A RC H Point-Of-Care Ultrasonography for Diagnosis of Medial Collateral Ligament Tears in Acute Knee Trauma; a Diag- nostic Accuracy Study Omid Ahmadi1, Farhad Heydari1∗, Keihan Golshani1, Sirous Derakhshan1 1. Department of Emergency Medicine, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Received: March 2022; Accepted: May 2022; Published online: 9 June 2022 Abstract: Introduction: The use of point-of-care ultrasonography (POCUS) for identifying medial collateral ligament (MCL) tears has increased in recent years. This study aimed to evaluate the diagnostic accuracy of POCUS in the diagnosis of acute MCL tears of the knee. Methods: This prospective cross-sectional study was performed on patients with suspected MCL tear of the knee in the emergency department (ED). After history taking and primary physical examination, radiographic imaging of the knee was done. If there was no fracture in the knee X-ray, the POCUS examination was done. All of the patients were asked to refer to an orthopedic clinic, 7-10 days after discharge from ED, for Magnetic Resonance Imaging (MRI) evaluation. The second POCUS was done in the orthopedic clinic. Finally, the findings of POCUS and MRI were compared in diagnosing MCL injury. Results: Two hundred and fifty patients with a mean age of 25.05 ± 9.12 years were analyzed (86.8% male). According to the MRI findings, as the gold standard, 55(22.0%) patients had MCL injury. The sensitivity, specificity, pos- itive and negative predictive values (PPV and NPV ), and accuracy of ultrasound in detection of MCL injury, in comparison with MRI were 83.64 (95% CI, 71.20 to 92.23), 94.36% (95% CI, 90.13 to 97.15), 80.70% (95% CI, 69.95 to 88.25), 95.34% (95% CI, 91.83 to 97.38), and 92.00% (95% CI, 87.92 to 95.05), respectively. The area under the receiver operating characteristic (ROC) curve of POCUS was 0.890 (95% CI, 0.844 to 0.926). Conclusion: It seems that POCUS can be applied in screening patients with MCL tears following blunt knee trauma. Keywords: Medial Collateral Ligament, Knee; Ultrasonography; Magnetic Resonance Imaging; Emergency Service, Hospital Cite this article as: Ahmadi O, Heydari F, Golshani K, Derakhshan S. Point-Of-Care Ultrasonography for Diagnosis of Medial Col- lateral Ligament Tears in Acute Knee Trauma; a Diagnostic Accuracy Study. Arch Acad Emerg Med. 2022; 10(1): e47. https://doi.org/10.22037/aaem.v10i1.1480. 1. Introduction The medial collateral ligament (MCL) is one of the four major ligaments of the knee (1). It extends from the medial femoral epicondyle to the medial tibial condyle and medial surface of its body (2). The superficial MCL is the most commonly damaged ligament of the knee after direct knee trauma and is mostly caused by valgus stress (3). An MCL injury is a sprain or tear to the medial collateral ligament (4). It is usually diagnosed through physical ex- amination of the knee (5). But initial pain and swelling sometimes make it very difficult to judge the severity of the ∗Corresponding Author: Farhad Heydari; Department of Emer- gency Medicine, Alzahra Hospital, Sofeh Ave, Keshvari Blvd., Isfahan, Iran.Email: farhad_heidari@med.mui.ac.ir, Phone: +989131367643, OR- CID: https://orcid.org/0000-0002-6296-0045. injury; therefore, it is important to use an imaging modality to confirm the diagnosis (6, 7). Early and accurate diagnosis of MCL injury is very important for determining the suitable treatment to return to function in a short time (4, 8). MRI has been considered as the non-invasive diagnostic gold standard modality, but it is costly, not available in all centers, and needs long waiting periods (5, 9). Also, MRI has major limitations and cannot be used for those with metal implants, indwelling cardiac pacemakers, and claustropho- bia (10, 11). Recent studies showed that point-of-care ultrasound (POCUS) is an alternative, portable, non-invasive, and real-time imaging modality for evaluating the soft tissue pathology of the knee (9, 10, 12-14). POCUS is easier to ac- cess, has lower costs, and is quicker than MRI for diagnosis of MCL tear (3, 5). Therefore, the use of POCUS for identifying MCL tears has increased in recent years. This study aimed to assess the accuracy of POCUS in diagnosis of MCL tears in 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 O. Ahmadi et al. 2 comparison with MRI, as the gold standard reference. 2. Methods 2.1. Study design and setting This prospective cross-sectional study was conducted be- tween 2020 and 2021 in the emergency department (ED) of Kashani Hospital, Isfahan, Iran. The study received ethics approval from the ethics committee of Isfahan University of Medical Sciences (IR.MUI.MED.REC.1397.091). All pa- tients were included after obtaining written informed con- sent. Researchers adhered to ethical principles of declaration of Helsinki and confidentiality of patients’ information. 2.2. Participants All patients with acute knee injuries and suspected acute MCL injury following blunt trauma based on clinical ex- amination findings were included in the study. Suspected acute MCL injury has been defined as medial knee pain, tenderness, and swelling following acute blunt knee trauma (trauma in the last 3 days). Using convenience sampling, patients were enrolled 24 hours a day during all days of the week. Patients younger than 18 years, those with multiple trauma, unstable hemodynamics, loss of consciousness, history of a previous MCL tear or previous injury on the injury site, diag- nosis of a fracture in the knee, and contraindications to MRI, and those who declined to participate in the study and re- fused to continue treatment and orthopedic follow-up were excluded. 2.3. Study protocol After history taking and primary physical examination, two- view radiographic imaging (AP and lateral X-ray) of the knee was performed. If there was no fracture in the knee X-ray, the point-of-care sonographic (POCUS) examination on the knee was carried out by one of the four trained emergency medicine specialists. Each sonographer received two hours of theoretical and two hours of practical instructions by a ra- diologist who was an expert in musculoskeletal US. After the POCUS examination, the US findings were recorded on data collection sheets. The injured knee was always treated with a cylindrical splint of the lower limb. All of the patients were asked to refer to an orthopedic clinic with prior coordination and arrangement 7-10 days after dis- charge from ED. Second POCUS was done in the orthopedic clinic and then the patient was examined by a specific or- thopedic specialist who was blinded to the POCUS results. Ultrasounds were performed by two different sonographers. After that, MRI was performed. The diagnosis of MCL tear was made based on MRI findings. The radiologists who were blinded to the POCUS findings evaluated the MRI. The MRI machine used in this study was GE Tesla (General Electric Company of America). The collected variables included age, sex, clinical findings, first and second POCUS, and MRI findings were recorded on data collection forms. Finally, POCUS findings were com- pared to MRI findings in diagnosing MCL injury. 2.4. Ultrasound technique Ultrasound was performed using Philips Affiniti 50G ultra- sound machine with Liner probe (5-12 MHz). The ultrasound examination was done in prone position with 20-30 degrees of knee flexion and slight external rotation of the hip joint. The transducer was placed on a longitudinal plane at the me- dial aspect of the knee at the MCL site. MCL with hypere- choic and fibrillar structure in a longitudinal plane was con- sidered intact, while thickening and heterogeneously hypoe- choic changes in the MCL were considered as injured MCL (3, 5). 2.5. Statistical analysis The sample size was calculated at the confidence interval of 95%, with sensitivity of 84.6% based on the results of a previ- ous study (9), and the error level of 0.06. Thus, the required sample size was 244. Finally, the collected data was entered into SPSS software (Ver. 25) and was presented as number (%) or mean ± standard deviation (SD). Accuracy, sensitivity, specificity, positive predictive value (PPV ), and negative pre- dictive value (NPV ) of POCUS for the identification of MCL tear were calculated. 3. Results 3.1. Baseline characteristics of studied cases A total of 315 patients with suspected MCL injury after acute blunt knee trauma were initially assessed for eligibility, 55 of whom were excluded. Thus, two hundred and sixty patients were enrolled in the study. Then ten patients did not un- dergo MRI due to the lack of orthopedic follow-up. Finally, 250 patients with a mean age of 25.05 ± 9.12 years were stud- ied (86.8% male). The study flow diagram is shown in Figure 1. The patients’ demographic and clinical findings are pre- sented in Table 1. According to the MRI findings, as the gold standard, 55(22.0%) patients had MCL injury, while POCUS showed that 57 (22.8%) patients had MCL injuries (Table 1). 3.2. Screening performance characteristics In comparison with MRI scans, the sensitivity, specificity, PPV, NPV, and accuracy of ultrasonography in the detection of MCL injury were 83.64 (95% CI, 71.20 to 92.23), 94.36% (95% CI, 90.13 to 97.15), 80.70% (95% CI, 69.95 to 88.25), 95.34% (95% CI, 91.83 to 97.38), and 92.00% (95% CI, 87.92 to 95.05), respectively. The area under the receiver operating 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. 2022; 10(1): e47 Figure 1: CONSORT Flow Diagram of patient enrollment. Table 1: Baseline characteristics of the studied patients Variable Value Gender Male 217 (86.8) Female 33 (13.2) Age (year) Mean ± SD 25.05 ± 9.12 Clinical Findings of knee Pain 250 (100) Tenderness 248 (99.2) Swelling 226 (90.4) MCL tear on Ultrasonography Yes 57 (22.8) No 193 (77.2) MCL tear on MRI Yes 55 (22.0) No 195 (78.0) Data are presented as mean ± standard deviation (SD) or frequency (%). MCL: medial collateral ligament; MRI: magnetic resonance imaging. characteristic (ROC) curve of the POCUS exam in the detec- tion of MCL injuries was 0.890 (95% CI, 0.844 to 0.926). The sensitivity, specificity, PPV, NPV, and accuracy of the second POCUS exam after one week are shown in table2. 4. Discussion In the current study, sensitivity, specificity, PPV, NPV, and ac- curacy of US in diagnosis of MCL tears following acute blunt knee trauma, as compared to MRI, were 83.64%, 94.36%, 80.70%, 95.34%, and 92.00%, respectively. Recently, the US exam has been widely used as a screening musculoskeletal imaging modality. The advantages of ultra- sound include safety, saving health care costs, ease of use, and portability of the equipment. However, there are limita- tions to the use of ultrasound, such as dependence on oper- ator’s training, skills, and experience. The US has been used for detecting knee injuries in various studies with different results (15). Therefore, in the current study, the accuracy of POCUS in diagnosis of MCL tears was evaluated. The mean age in the present study was 25 years and 217 par- ticipants were male (86.8%), which were similar to previous studies (9-11). The males are more likely to have traumatic knee injuries because they are more physically active dur- ing the day (9). According to the MRI findings, 55(22.0%) patients had MCL injuries. A study on sixty patients with clinically suspected meniscal/ligamentous injury of the knee demonstrated that 13 patients had MCL injuries based on MRI (9). Ghosh et al. evaluated 9 patients with medial knee pain scheduled for a knee MRI (3). They had three cases with MCL pathology on MRI (1 chronic and 2 acute). The preva- lence of MCL injury in these studies is similar to the present study. In the current study, sensitivity, specificity, PPV, NPV, and ac- curacy for the US, as compared to MRI, in diagnosis of MCL tears were 83.64%, 94.36%, 80.70%, 95.34%, and 92.00%, re- spectively. Consistent with the results of the present study, Singh et al. demonstrated that sensitivity, specificity, and ac- curacy of ultrasound in diagnosis of MCL injuries, compared with MRI were 84.6%, 100%, and 96.6% (9). In another study, the US had 83.33% sensitivity 97.73% specificity, and 96% ac- curacy for MCL tears (10). These results are compatible with the current study. Ghosh et al. showed that US had a sensitivity of 67%, and specificity of 83%, PPV of 67%, and NPV of 83% for iden- tifying MCL tears (3). They evaluated acute and chronic knee injuries and only subjects with chronic MCL changes were missed on ultrasound. They suggested that the US may have a limited role in evaluating chronic ligamentous injuries. In a study performed by Najafi et al., the sensi- tivity, specificity, PPV, NPV, and accuracy of US in diagno- sis of complete MCL tears were 66%, 98%, 50%, 99%, and 97%, respectively (5). In this study, which was performed in a referral sports medicine center for arthroscopic candi- date patients with acute and chronic knee trauma, a small proportion of patients had complete MCL tears; therefore, the results could not be generalized. In the present study, the specificity slightly decreased after one week (94.36% and 93.33%). Despite the low sensitivity of US in diagnosis of chronic MCL ligament injuries, it is a useful tool for the im- mediate diagnosis of acute MCL injuries in selected subjects, for whom MRI is contraindicated, or when MRI is not avail- able, so that treatment can be started earlier. 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 O. Ahmadi et al. 4 Table 2: Diagnostic value of ultrasound in diagnosis of medial collateral ligament injury in emergency department on admission (first) and one week after the injury (second) MRI First Ultrasound Second Ultrasound Positive (n=57) Negative (n=193) Positive (n=59) Negative (n=182) Positive (n= 55) 46 9 46 9 Negative (n= 195) 11 184 13 182 Screening performance characteristics Characteristic First Ultrasound Second Ultrasound AUC 0.890 (0.844 - 0.926) 0.885 (0.839 – 0.922) Sensitivity 83.64 (71.20 - 92.23) 83.64 (71.20 - 92.23) Specificity 94.36 (90.13 - 97.15) 93.33 (88.87 - 96.40) Positive Predictive Value 80.70 (69.95 - 88.25) 77.97 (67.39 - 85.84) Negative Predictive Value 95.34 (91.83 to 97.38) 95.29 (91.74 - 97.35) Negative Likelihood Ratio 0.17 (0.09 to 0.32) 0.18 (0.09 - 0.32) Positive Likelihood Ratio 14.83 (8.25 - 26.64) 12.55 (7.33 - 21.49) Accuracy 92.00 (87.92 – 95.05) 91.20 (86.98 - 94.40) Data was expressed with 95% Confidence Interval. AUC: Area under the receiver operating characteristic (ROC) curve; MRI: magnetic resonance imaging. Finally, POCUS is a highly sensitive, specific, and accurate modality for acute MCL tears. This study examined the role of POCUS as an initial first-line modality in the evaluation of MCL tears. For patients with clinical suspicion to MCL injury, POCUS was suggested as an initial imaging tool of choice. MRI can be recommended as the next line modality for fur- ther evaluation. 5. Limitations There are limitations in the present study. This was a single- centered study with limited generalizability. It was better to perform it with a larger sample size as well as in several cen- ters. Also, only MCL was examined. To determine the simul- taneous medial meniscus tear, it was better to evaluate the internal compartment of the knee with ultrasound. 6. Conclusion The present study found that POCUS is a useful adjuvant di- agnostic modality for evaluating MCL tears. POCUS helps in taking a decision regarding management of an MCL tear, while the patient can avoid undergoing the costly and time- consuming confirmatory MRI if the result is negative, unless they do not improve during the follow-up period. Therefore, POCUS is recommended as a useful initial modality in pa- tients with suspected MCL injuries. 7. Declarations 7.1. Acknowledgments The authors appreciate the insightful cooperation of the staff of the emergency department of Kashani Hospital, Isfahan, Iran. 7.2. Authors’ contributions O.A., F.H., K.G., S.D.; Contributed to conception and design. O.A., F.H., S.D.; Contributed to the all-experimental works, data gathering and statistical analyses, as well as interpreta- tion of data. O.A., F.H.; Were responsible for overall supervi- sion. F.H.; Drafted the manuscript, revised by O.A., K.G. and S.D. All authors performed editing and approving the final version of this paper for submission. They also participated in the finalization of the manuscript and approved the final draft. 7.3. Funding and supports This study was funded by Isfahan University of Medical Sci- ences. 7.4. Competing interests The authors declare no conflict of interest. 7.5. Ethics approval and consent to participate Ethical approval was obtained from the ethics com- mittee of Isfahan University of Medical Sciences (IR.MUI.MED.REC.1397.091). References 1. Tsai W-H, Chiang Y-P, Lew RJ. Sonographic Exami- nation of Knee Ligaments. Am J Phys Med Rehabil. 2015;94(8):e77-e9. 2. Lee MJ, Chow K. Ultrasound of the knee. Semin Muscu- loskelet Radiol. 2007;11(2):137-48. 3. Ghosh N, Kruse D, Subeh M, Lahham S, Fox J. Compar- ing point-of-care-ultrasound (POCUS) to MRI for the di- 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 5 Archives of Academic Emergency Medicine. 2022; 10(1): e47 agnosis of medial compartment knee injuries. J Med Ul- trasound. 2017;25(3):167-72. 4. Andrews K, Lu A, McKean L, Ebraheim N. Review: Medial collateral ligament injuries. J Orthop. 2017;14(4):550-4. 5. Najafi J, Bagheri S, Lahiji FA. The Value of Sonogra- phy With Micro Convex Probes in Diagnosing Meniscal Tears Compared With Arthroscopy. J Ultrasound Med. 2006;25(5):593-7. 6. Marchant MH, Tibor LM, Sekiya JK, Hardaker WT, Gar- rett WE, Taylor DC. Management of Medial-Sided Knee Injuries, Part 1:Medial Collateral Ligament. Am J Sports Med. 2011;39(5):1102-13. 7. Cook JL, Cook CR, Stannard JP, Vaughn G, Wilson N, Roller BL, et al. MRI versus ultrasonography to assess meniscal abnormalities in acute knees. J Knee Surg. 2014;27(4):319-24. 8. Encinas-Ullán CA, Rodríguez-Merchán EC. Isolated me- dial collateral ligament tears: an update on manage- ment. EFORT Open Rev. 2018;3(7):398-407. 9. Singh A, Mangat I, Thukral C, Gupta K. Diagnostic ac- curacy of ultrasonography in evaluation of knee injuries with magnetic resonance imaging correlation. Int J Anat Radiol Surg. 2018;7(1):50-5. 10. Singh B, Pawar KN, Kachewar S, Ghule SS, Lakhkar DL. Evaluation of knee joint by ultrasound and MRI. IOSR J Dent Med Sci. 2016;15(10):122-31. 11. El-Monem SA, Enaba MM. Comparative study between High Resolution Ultrasound (HRUS) and MRI in diagno- sis of meniscal and cruciate ligaments injury of the knee. Med J Cairo Univ 2012;80(2):233-42. 12. Zamani M, Mazaheri M, Heydari F, Masoumi B. Compar- ison of diagnostic accuracy of bedside ultrasonography and radiography for calcaneal fractures in the emergency department. J Emerg Pract Trauma. 2021;7(1):17-21. 13. Artul S, Khazin F, Hakim J, Habib G. Ultrasonographic findings in a large series of patients with knee pain. J Clin Imaging Sci. 2014;4:45-. 14. Ahmadi O, Motififard M, Heydari F, Golshani K, Azimi Meibody A, Hatami S. Role of point-of-care ultrasonogra- phy (POCUS) in the diagnosing of acute medial meniscus injury of knee joint. Ultrasound J. 2022;14(1):1-8. 15. Makhmalbaf H, Shahpari O. Medial Collateral Ligament Injury; A New Classification Based on MRI and Clinical Findings. A Guide for Patient Selection and Early Surgical Intervention. Arch Bone Jt Surg. 2018;6(1):3-7. 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 Introduction Methods Results Discussion Limitations Conclusion Declarations References