Written by: Jason Chodakowski, MD (NUEM PGY-3) Edited by: Logan Weygandt, MD (NUEM ‘17) Expert commentary by: Rachel Haney, MD (NUEM ‘17)
Why use Ultrasound?
Distal forearm fractures are common fractures in the pediatric population. Although plain radiographs of the forearm are still considered the gold standard for definitive diagnosis, there is growing interest in using ultrasound for diagnosis because it provides zero radiation exposure, it can be used to guide local pain control, and it can confirm reduction success at the bedside. Ultrasound is easy to teach and provides value under circumstances when plain radiography might be unavailable (pre-hospital environment, disaster areas, or in developing countries).
A recent meta-analysis of 12 studies, which included 951 children 18 and younger, found that physician performed bedside ultrasound detected distal forearm fractures with a pooled sensitivity of 98% and a specificity of 96% when compared with the gold standard plain radiographs.[1] The pain associated with ultrasound use was also significantly less.[2]
How do I use Ultrasound?
To evaluate musculoskeletal pathology use the high-frequency linear array transducer employing the six-view ultrasound technique as shown below. You may detect a fracture as an apparent discontinuity or irregularity (divots, step-offs, distortion) of the hyperechoic and continuous bony cortex. Disruptions as small as 1mm can be detected.
Six-view technique (Herren et. al. 2015)
Normal Cortex (Crosby et. al. 2014)
Distal radius fracture (emergencyultrasoundteaching.com)
Distal radius fracture (acep.org)
Pitfalls
In children the evaluation of bones is complicated by the open physes, which may be mistaken for fractures. The difference is that physes will appear as smooth, downward-sloping curves unlike fractures, which will have abrupt step-offs.
Normal open tibial physis (Crosby et. al. 2014)
What else is Ultrasound Good For?
Confirming reductions
Ultrasound is also utilized by emergency physicians to determine successful realignment of pediatric distal forearm fractures after closed reduction.[4]
Fracture reduction (Socranksy et. al. 2016)
Achieving adequate pain control
Ultrasound can also be used to guide hematoma blocks. The hematoma block is a technique wherein the physician injects an anesthetic solution into the hematoma between the fractured bone fragments (see image below). It has been shown to be effective, safe, faster, and uses fewer resources with no significant difference in pain scores when compared to procedural sedation in both adults and children with distal forearm fractures.[6,7]
Clean skin and place a sterile cover over the transducer. Using 5-10cc of 1-2% lidocaine inject into the hematoma between the fractured bone fragments using an 18-22 gauge needle.
Visualization of needle (N) entering between fracture bone fragments (U) (emdocs.net)
Take Home Points
Ultrasound is most useful in evaluating long bone fractures such as the femur, clavicle, ribs, or distal radius and ulna.
A reliable alternative to the plain radiograph is the proper six-view method it, with the advantages of being portable and radiation-free.
Ultrasound can also be reliably used to confirm fracture reduction, as well as for guiding forearm fracture hematoma blocks.
Expert Commentary
Thank you for providing a concise summary of the utility of Point-of-care Ultrasound (POCUS) for pediatric forearm fractures.
I’d like to mention a few key points regarding the use of POCUS for pediatric fracture assessment.
If you do a lot of adult scanning and not much pediatric scanning it is important to keep in mind that children may not be as cooperative (or stationary) as adults.
Smaller children may be afraid of the transducer therefore introducing the transducer to the patient as an object that will not hurt them is key. You should hand the probe to the patient, allow them to touch it and even scan themselves initially in order to get them more comfortable with the probe.
While the 6-view scan you describe will certainly improve sensitivity, adequate sensitivity can be achieved with a 2-view approach. Additionally, the 6-view technique may be prohibitively time-intensive in a busy Emergency Department.
In order to increase sensitivity with the 2-view approach, always start imaging at the point of maximal tenderness, initially in the longitudinal plane with the cortex of the bone parallel to the probe surface. Slide distal and proximal to the point of tenderness. Then rotate the probe 90 degrees to view the cortex in the transverse plane. Fractures are noted as cortical disruptions or step-offs. Fractures are most visible on POCUS when the fracture line is perpendicular to the angle of insonation.
Another key pearl is to use copious gel in order to optimize the focal point of the image. The focal zone on the screen is the part of the image with the highest resolution secondary to convergence of the US beams. The focal point can be changed depending upon your machine, but is typically no more shallow than about 1-cm below the probe surface, therefore if you place a good layer of gel about 1cm thick, you will place the cortext of the bone at the optimal focal point. Using copious gel is also important in reducing any potential discomfort caused by pressure from the probe.
If gel is a limited resource, you can use a water bath as well.
While POCUS is a wonderful tool, especially for fracture detection, I want you to keep in mind that the sensitivity of POCUS for fractures is the highest (low-mid 90s) for the diaphysis of long bones (femur, humerus, radius and ulna). Sensitivity is significantly lower for detecting fractures of other bones and fractures near joint lines secondary to the curvilinear nature of the metaphysis as well as the presence of cartilaginous epiphyseal plates in children.
While POCUS can supplant the use of radiography in austere environments, in a well-resourced emergency department, POCUS should be an adjunct to radiography. In this setting, POCUS can have utility in patients in whom you suspect occult fracture despite negative XRs or for real-time fracture reduction assessment before sedation wears off. Unless you are a pediatric POCUS expert, I would order XR’s as usual for a pediatric patient you suspect has a fracture. In the meantime- continue scanning patients with normal anatomy and documented fractures in order to develop your POCUS expertise! Happy Scanning!
Rachel Haney, MD
NUEM ‘17
Ultrasound Fellow at Massachusetts General Hospital
How To Cite This Post
[Peer-Reviewed, Web Publication] Chodakowski J, Weygandt L. (2019, April 28). Ultrasound in pediatric distal forearm fractures. [NUEM Blog. Expert Commentary by Haney R]. Retrieved from http://www.nuemblog.com/blog/us-for-fracture
Other Posts You May Enjoy
References
Douma-den Hamer, Djoke, et al. "Ultrasound for Distal Forearm Fracture: A Systematic Review and Diagnostic Meta-Analysis." PloS one 11.5 (2016): e0155659.
Chaar-Alvarez FM, Warkentine F, Cross K, et al. Bedside ultrasound diagnosis of nonangulated distal forearm fractures in the pediatric emergency department. Pediatr Emerg Care 2011; 27:1027.
Herren C, Sobottke R, Ringe MJ, et al. Ultrasound-guided diagnosis of fractures of the distal forearm in children. Orthop Traumatol Surg Res 2015; 101:501.
Dubrovsky, Alexander Sasha, et al. "Accuracy of ultrasonography for determining successful realignment of pediatric forearm fractures." Annals of emergency medicine 65.3 (2015): 260-265.
Socransky, Steve, et al. "Ultrasound-Assisted Distal Radius Fracture Reduction." Cureus 8.7 (2016).
Fathi, M. et al. Ultrasound-guided hematoma block in distal radius fracture reduction: a randomized clinical trial. Emerg Med J. 2014 Jul 12.
Bear, David M., et al. "Hematoma block versus sedation for the reduction of distal radius fractures in children." The Journal of hand surgery 40.1 (2015): 57-61.