AP view shoulder

Have you ever been working a shift at 3 am and wondered, “Am I missing something? I’ll just splint and instruct the patient to follow up with their primary doctor in 1 week.” This is a reasonable approach, especially if you’re concerned there could be a fracture. But we can do better. Enter the “Can’t Miss” series: a series organized by body part that will help identify injuries that ideally should not be missed. This list is not meant to be a comprehensive review of each body part, but rather aims to highlight and improve your sensitivity for these potentially catastrophic injuries. Now: the shoulder

The Shoulder

  • Third most common musculoskeletal complaint, only to low back pain and neck pain [1].
  • Most commonly dislocated major joint [2].
  • Epidemiology: Posterior dislocations are much less common than anterior, but associated with more life-threatening injuries such as pneumothorax and laceration of great vessels, trachea, or esophagus [2]. May see pneumothorax with anterior dislocation.
  • Mechanism: Usually high speed motor vehicle collision or contact sports injuries
  • Symptoms: Severe pain exacerbated by arm motion and lying supine [2]
  • Physical Exam: Medial clavicle end is less visible and often not palpable. The patient may have signs of impingement of important mediastinal structures, for example stridor or shortness of breath.
  • Diagnostic Imaging: Routine clavicle radiographs or “serendipity” views  may not be diagnostic. If there is a high index of suspicion, the patient needs a CT chest with contrast to view the underlying vessels.
  • Treatment:
    • Anterior dislocations may be discharged without reduction attempt if uncomplicated [2].
    • Posterior dislocations require orthopedics consultation for closed reduction of posterior dislocations [2]. Because of the close-lying great vessels, these reductions should be performed at a facility that has vascular surgery on call.

Figure 1: Right posterior sternoclavicular dislocation. Case courtesy of Dr Brendon Friesen, Radiopaedia.org.

  • Epidemiology: Acromioclavicular joint injuries account for half of all shoulder injuries among those involved in contact sports [3].
  • Mechanism: Direct trauma to acromioclavicular joint, typically a fall on a adducted arm
  • Symptoms: Distal clavicle or shoulder pain
  • Physical Exam: Tenderness over acromioclavicular joint
  • Diagnostic X-Ray: Grade 1 AC injuries are characterized by pain at the AC joint with a negative film. On the other hand, Grade 4 injuries often require lateral view for diagnosis, as the clavicle is dislocated posteriorly. Check out our SplintER series post on acromioclavicular separations for more information.
  • Treatment: Rest, ice, immobilization with sling followed by early range of motion exercises at 7-14 days

Figure 2:  Various Acromioclavicular joint injuries. Case courtesy of Andrew Murphy, Radiopaedia.org.

  • Epidemiology: Commonly missed; it represents < 5% of all dislocations [2]
  • Mechanism: Indirect force that produces forceful internal rotation and adduction Classically seizure or electric shock. Can also occur from direct blow to anterior shoulder [2]
  • Symptoms: The patient will not allow external rotation or abduction.
  • Physical Exam: Arm is typically adducted and internally rotated
  • Diagnostic Imaging: Check scapula “Y” or axillary view. On AP view, the patient may appear to have a “Light Bulb” sign as the greater tuberosity is rotated anteriorly.
  • Treatment: Reduction and immobilization in an arm sling, with orthopedics follow up

Figure 3: Posterior dislocation. Case courtesy of Andrew Murphy, Radiopaedia.org

  • Epidemiology:
    • Scapular body: Rare but associated with many significant injuries
    • Acromion fractures: Rare but often associated with other injuries
    • Scapular neck fractures: 25% of all scapular fractures [1]
    • Glenoid fractures: 50% of all scapular fractures [1]
  • Mechanism: Scapular body and acromion fractures generally require significant force and usually occur from blunt trauma. Scapular neck and glenoid fractures usually occur from lower mechanisms, such as  falling on an outstretched arm, falling onto the elbow, or a lateral blow to the shoulder [1].
  • Symptoms: Posterior shoulder or scapular pain, may have pain elsewhere if concomitant injury
  • Physical Exam: Tender to palpation over scapula or posterior thoracic cage
  • Diagnostic X-Ray: If a scapular fracture is seen on x-ray, should strongly consider CT to assess for concomitant injuries
  • Treatment: Non-displaced fractures of the body, neck and glenoid require sling and outpatient follow up [1]. Patients with acromion fractures should be treated with shoulder immobilizer [1].

Figure 4: Scapular fracture. Case courtesy of Dr Ian Bickle, Radiopaedia.org

  • Epidemiology: Accounts for 20% of all proximal humerus fractures [4]
  • Mechanism: May occur from a variety of mechanisms but is most commonly associated with anterior dislocation or direct blow [4]
  • Symptoms: Persistent rotator cuff symptoms or shoulder pain
  • Physical Exam: Pain with abduction and external rotation after shoulder trauma. Tenderness to palpation at greater tuberosity [4].
  • Diagnostic X-Ray: May initially be negative. Obtaining an AP view with external rotation of humerus increases sensitivity [4].
  • Treatment: Sling with slight internal rotation but ok to remove for bathing, exercises [4]

Figure 5: Greater tuberosity fracture. Case courtesy of Dr Bruno Di Muzio, Radiopaedia.org

  • Epidemiology: Often mistaken for shoulder dislocation leading to providers attempting to reduce. Do not try to “reduce” as it will only cause patient pain. Usually signifies occult fracture.
  • Mechanism: Direct blow or fall on outstretched hand.
  • Symptoms: Shoulder pain
  • Physical Exam: Pain with ROM at shoulder.
  • Diagnostic X-Ray: Inferior displacement of humeral head on AP, as a hemarthrosis often displaces humerus inferiorly. However, axillary Y does not show evidence of dislocation.
  • Treatment: Sling and early range of motion [5]

Figure 6:Shoulder pseudosubluxation. Note, on “Y” view that humerus is in the appropriate location, just inferiorly displaced.  Case courtesy of Radswiki, Radiopaedia.org

Many of the common pathology outlined above can cause concomitant injuries. Be sure to check for pneumothoraces and rib fractures when visible on the obtained films, and the dreaded incidental finding of the Pancoast Tumor, Osteonecrosis of humeral head (Hass Disease). If the patient reports no trauma, or minimal trauma that does not explain their level of pain or disability, consider septic joints.

Want a basic approach to traumatic shoulder imaging? Check out EMRad’s Approach to the traumatic shoulder. 


  1. 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 25892724
  2. 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
  3. Warth, R. Acromioclavicular Joint Separations. Curr Rev Musculoskelet Med.2013 Mar; 6(1): 71–78. PMC 3702768
  4. Longo, U. et al. Missed Fractures of the greater tuberosity. BMC Musculoskeletal Disorders. Volume 19. Issue 1. Aug 2018. PMID 30170571
  5. Pritchett, J. Inferior sublaxation of the humeral head after trauma or surgery. J shoulder elbow surg. Volume 4. July-August 1997. PMID 9285875 
Stephen Villa, MD

Stephen Villa, MD

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