EMRad: Radiologic Approach to the Traumatic Elbow

Radiology teaching during medical school is variable, ranging from informal teaching to required clerkships.^​1​ Many of us likely received an approach to a chest x-ray, but approaches to other studies may or may not have not been taught. We can do better! Enter EMRad, a series aimed at providing approaches and improving interpretation of commonly ordered radiology studies in the emergency department. When applicable, it will provide pertinent measurements specific to management, and offer a framework for when to get an additional view, if appropriate. To begin: the elbow. 

Learning Objectives

1. Interpret elbow x-rays using a standard approach
2. Identify clinical scenarios in which an additional view might improve pathology diagnosis

Why the elbow matters and the radiology rule of 2’s

The Elbow

• Approximately 2-3% of all ED visits involve the elbow.^​2​
• Missed elbow injuries can be highly morbid.

Before we begin: Make sure to employ the rule of 2’s^​3​

• 2 views: One view is never enough.
• 2 abnormalities: If you see one abnormality, look for another.
• 2 joints: Image above and below the injury (especially for forearm and leg).
• 2 sides: If unsure regarding a potential pathologic finding, compare it to another side.
• 2 occasions: Always compare with old x-rays if available.
• 2 visits: Bring the patient back for repeat films.

An approach to the traumatic adult elbow x-ray

1. Adequacy/Alignment
2. Effusions or fat pads
3. Bones
4. Consider an additional view

1. Adequacy/Alignment

• Lateral View
  • Check for a “Figure of 8” to ensure that this is a true lateral view.

• Anterior humeral line
  • A line drawn along the anterior aspect of the humerus should intersect the middle ⅓ of the capitellum. 
  • If it does not, consider distal humerus fracture.

• Radiocapitellar line
  • A line drawn along the middle of the radius should intersect the capitellum.  
  • If not, consider radial head dislocation or subluxation.

2. Check for effusions or fat pads

Lateral View

• An anterior fat pad can be normal but if excessive or “sail sign” think radial head fracture in adults
• An posterior fat pad is always pathologic. In adults, this indicates intra-articular trauma.

How do you know when too much is too much? The normal anterior fat pad is typically parallel to the humerus, usually angulated ≤15 degrees from the humeral shaft. When there is a significant effusion, it appears more angulated or like a sail, hence a “Sail Sign.”^​4​

3.   Bones

• Trace the bone cortex carefully on both AP and lateral views.
• Pay close attention to all aspects of the humerus, radius, olecranon.

4. Consider an additional view

External Oblique View

• When: Sometimes included as the 3rd view in a series
• Why: This is better at seeing the radial head. Consider obtaining this view if there is a high suspicion for radial head fracture.

Coyles View

• When: High index of suspicion for radial head fracture

Learn More

• Find an abnormality and not sure which splint to apply? Read more about this in our SplintER Series: Common ED Splint Techniques.
• Afraid you might miss something commonly missed or catastrophic? Read more at “Can’t Miss” Elbow Injuries.
• Want a more in-depth approach to elbow radiography? Take a radiology master class or check out Radiopaedia’s approach.

Author information

Stephen Villa, MD

Medical Education Fellow
Department of Emergency Medicine
University of California, Los Angeles

|

The post EMRad: Radiologic Approach to the Traumatic Elbow appeared first on ALiEM.