Standardized sonographic examination of pediatric elbow injuries is an effective screening method and improves diagnostic efficiency

Abstract

Introduction: Positive role of ultrasound in the diagnosis of pediatric elbow injuries were confirmed by many papers but no comprehensive, standardized method has been developed for daily clinical practice. The aim of our prospective diagnostic study was to prove the efficacy of a five point sonographic point of care method for detecting different pediatric elbow fractures or dislocations.

Methods: Between 2016 January and 2017 March 365 children (age 1-14) with suspected closed elbow injury were enrolled in our study. Sonographic point of care examination was carried out by a properly trained resident and two orthopedic surgeons immediately after physical survey. We used a standardized five point sonographic examination. Two plane x-rays were made following sonography according to protocol. Utility of sonographic pictures were analyzed by a radiologist. Cases with images which have not met with standard requirements were excluded. In those cases when primary x-rays were negative and/or any of the ultrasound planes showed positive findings, radiography was repeated after 4 weeks of injury. If we detected callus formation the fracture was considered occult. Cases with images which have not met with standard requirements were excluded. Ultrasonic pictures, evaluation sheets and x-ray results were compared.

Results: Out of the 365 cases we identified 165 with positive findings (45, 2%) by primary x-rays. Distribution of the different injuries were the following: Radial condylar fractures, (n = 29) supracondylar humeral fractures (n = 84 proximal radial fractures, (n = 19) proximal ulnar fractures, (n = 7) fractures with joint dislocations (n = 3) joint dislocations without fractures, n = 2 medial epicondyle fractures (n = 14) fracture combinations (n = 7) We did not find injuries in this series that we could not categorize into these groups. Evaluating the abnormal sonographic dorsal fat pad sign (FPS) as a sole parameter for fracture detection we found sensitivity: 0, 97, specificity: 0,97, positive predictive value: 0,97, negative predictive value: 0,97 Evaluating the effectivity of the four cortical planes we calculated sensitivity 0, 85 specificity 0.96 positive predictive value: 0. 95 negative predictive value 0.87. The overall values of the five planes were the following: specificity0.97 sensitivity 1, positive predictive value 0.97 negative predictive value: 1 Interrater agreements on the cortical plane abnormality were considered good at two examiners and very good at one examiner. (Kappa = 0.79, 0, 81, 0, 79) Agreements on differentiation of elevated, normal fat pad) or lipohaemarthrosis in sonographic pictures were very good in all cases. (Kappa = 0,83, 0,86,0,82) While identification of any displacement or dislocation was possible in 96%, of all cases(n = 59)the exact determination of the type of the injury was possible in only 70,3% (n = 116) CONCLUSIONS: Using the five point ultrasonic examination provides enough information for excluding or confirming the presence of any pediatric elbow fractures or dislocations. The method is quick, simple and can help in the immediate differentiation of the severity of injuries. Sonographic lipohaemarthrosis seems to be more sensitive than elevated fat pad sign for the detection of potential occult fractures. Positive cases should be cleared by x-rays because the exact nature of the fractures are not identifiable only by ultrasound.

Keywords: Fat pad sign; Lipohaemarthrosis; Pediatric elbow fracture; Ultrasound.