EMRad: Radiologic Approach to the Traumatic Shoulder

This is EMRad, a series aimed at providing “just in time” approaches to commonly ordered radiology studies in the emergency department [1]. When applicable, it will provide pertinent measurements specific  to management, and offer a framework for when to get an additional view, if appropriate. We have already covered the elbow, the wrist, and the foot and ankle. Next up: the shoulder.

Learning Objectives

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

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

The Shoulder

• Third most common musculoskeletal complaint, second only to low back pain and neck pain [3]
• Most commonly dislocated major joint [4]

Before we begin: Make sure to employ the rule of 2’s [5]

• 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 to another side
• 2 occasions: Always compare with old x-rays if available
• 2 visits: Bring patient back for repeat films.

An approach to the traumatic adult shoulder x-ray

The American College of Radiology recommends at least 3 views for acute traumatic shoulder pain [5]:

• AP in internal rotation for visualization of the lesser tuberosity
• AP in external rotation for visualization of the greater tuberosity
• Scapula Y or axillary view in place of true lateral.

For simplicity, we focus on the standard AP view. Because the axillary view is often difficult to obtain due to pain [2], we will focus on Scapula “Y” but will discuss the axillary view in the “one more view” section.

1. Adequacy
2. Bones
   • Humerus
   • Glenoid Fossa
   • Clavicle
   • Scapula body (Yellow)
   • Ribs
3. Cartilage/Joints
   • Glenohumeral joint
   • Acromioclavicular joint
   • Coracoclavicular joint
4. Consider an additional view

1.    Adequacy/Alignment

• • AP and Scapula “Y” or lateral view
    • The coracoid process, glenoid fossa, acromion process, spine of scapula, and humeral head should be identifiable [7].

 

Figure 1: A) Normal AP B) Normal Scapular “Y” views. Case Courtesy of Dr. Craig Hacking, Radiopaedia.org. Annotated version by Stephen Villa, MD.

2. Bones

• Trace cortex of all bones.
  • Humerus
  • Glenoid Fossa
  • Clavicle
  • Scapula

3. Cartilage/Joints

• Glenohumeral joint
  • Articular surfaces should be parallel
    • If not parallel, check a lateral or scapula “Y” view.
      • On AP, If the humeral head lies under the coracoid process, consider anterior shoulder dislocation.
    • Pearl: If glenohumeral alignment is in doubt, consider obtaining an axillary view
    • Pearl: If a significant joint effusion is seen but the humerus appears in the glenoid fossa on scapula “Y” view, consider humeral head fracture or glenoid fracture

Figure 2: A) AP and B) Scapula “Y” views demonstrating anterior shoulder dislocation.  Note that the humerus lies anterior to the glenoid cavity. Case courtesy of Radswiki, Radiopaedia.org

• • Acromioclavicular joint
    • Inferior border of clavicle and acromion should line up, if not consider an acromioclavicular joint injury
      • Acromioclavicular (AC) distance > 8 mm or > 3 mm as compared to the contralateral side, think AC joint rupture [7].
  • Coracoclavicular joint
    • Coracoclavicular (CC) distance > 13 mm or > 5 mm asymmetry compared to the contralateral side, think CC joint rupture [7].

Figure 3: A) Normal AP demonstrating normal inferior border of the acromion and clavicle.  Case Courtesy of Dr. Craig Hacking, Radiopaedia.org. B) Grade 3 acromioclavicular joint injury. Note distance between coracoid and clavicle. Case courtesy of A. Prof Frank Gaillard, Radiopaedia.org.

4. Consider an Additional View

Axillary View

• When: Strong suspicion of shoulder dislocations, proximal humerus pathology or glenohumeral surface abnormalities
  • Note: Patient must be able to abduct the arm
• Why: Clearly visualizes the humeral head and glenoid fossa without superimposition of other structures

Modified Axillary View

• When: The patient has too much pain to adequately perform an axillary view.
• Why: One study demonstrated that an AP with Modified Axillary view rather than AP with Scapula “Y” view performed better and missed fewer injuries, including one posterior shoulder dislocation missed by the scapula “Y” view [8].

Velpeau View:

• When: The patient has too much pain to obtain true axillary view or if they re-dislocate their shoulder upon taking post-reduction films
  • Very similar to “Modified Axillary View
• Why: Does not require movement of the arm and can be performed in a sling

Clavicle Views

• When: Concern for pathology to clavicle
• Why: Can be better at detecting subtle clavicle fractures
  • Pearl: If there is a concern for an acromioclavicular separation, a clavicle series can falsely miss Type 4 injury (posterior) if no lateral view of the shoulder is obtained.

“Serendipity” Views

• When: Suspicion for sternoclavicular dislocations
• Why: Obtained at an angle where the displacement of the clavicle is better appreciated

Read more about positive findings in our SplintER Series: Common ED Splint Techniques.

Afraid you might miss something commonly missed or catastrophic? Can’t miss shoulder injuries.

Dealing with a polytrauma? Check out EMRad’s approach to the wrist, elbow, foot, and ankle

References

1. Hurov J. Anatomy and mechanics of the shoulder: review of current concepts. J Hand Ther. Vol 22, No 4, 2009. Oct-Dec 2009. PMID: 19665864
2. Emond, M. Selective prereduction radiography in anterior shoulder dislocation: The Fresno-Quebec Rule. The Journal of Emergency Medicine. Vol. 55. Issue 2. Aug 2018. PMID: 29861274
3. Bonz, J et al. Emergency Department Evaluation and Treatment of the Shoulder and Humerus. Emerg Med Clin N Am. Vol 33. No 2. May 2015. PMID: 25892723
4. Rudzinski, J. et al. Chapter 268. Shoulder and Humerus Injuries. In: Tintinalli’s Emergency Medicine. A Comprehensive Guide, 7th edition. New York: McGraw-Hill Education, 2011. P1830-1841
5. Chan, Otto. Introduction: ABCs and Rules of Two. ABC of Emergency Radiology, Third Edition. Edited by Otto Chan. 2013 John wiley & Sons, Ltd. Published 2013.
6. Amini, B et al. ACR Appropriateness Criteria Shoulder Pain-Traumatic. J Am Coll Radiology. Vol 15, No 5s, May 2018. PMID 29724420
7. Nicholson, DA et al. ABC of Emergency Radiology: The Shoulder. BMJ. Vol 307. October 1993. PMID 1679125
8. Neep, MJ et al. Radiography of the acutely injured shoulder. Radiography. Vol 17, Issue 3, August 2011.
9. Bloom, M. et al. Diagnosis of Posterior Dislocation of the Shoulder with Use of Velpeau Axillary and Angle-Up Roentgenographic Views. J Bone Joint Surg Am. Volume 49. Issue 5. July 1967. PMID 6029262

 

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