What is the best course of action for a patient with shoulder pain after a Motor Vehicle Accident (MVA) with a CT scan showing a nonspecific bony structure posteriorly on a transscapular Y view?

Management of Nonspecific Bony Structure on Post-MVA Shoulder CT

Obtain additional orthogonal radiographic views immediately—specifically an axillary lateral view—as the scapular Y view alone is insufficient to exclude posterior shoulder dislocation, which is missed in over 60% of cases without proper imaging. 1, 2

Immediate Diagnostic Steps

The finding of a "nonspecific bony structure" posteriorly on a transscapular Y view after trauma is a red flag that demands further investigation before any treatment decisions are made. Here's why and what to do:

Complete the Standard Trauma Series

• The American College of Radiology mandates at least 3 views for shoulder trauma, with 2 being orthogonal—you currently have incomplete imaging that could be masking a significant injury. 3, 4

• Add an axillary lateral view immediately to complete the trauma series, as glenohumeral dislocations are frequently misclassified on limited views and posterior dislocations are notoriously missed without proper orthogonal imaging. 1, 4

• The standard trauma protocol should include: a Grashey projection (AP to the scapula with 30° posterior oblique), an axillary lateral view, and the scapular Y view you already have. 3

• Perform these radiographs upright rather than supine whenever the patient's condition permits, as shoulder malalignment can be underrepresented on supine imaging. 4, 5

Why This Matters Critically

• Posterior shoulder dislocations are missed in more than 60% of cases initially because they can appear deceptively normal on AP views alone, and your "nonspecific bony structure" could represent the posteriorly displaced humeral head. 1, 2

• The axillary view is essential because it definitively shows the relationship between the humeral head and glenoid—attempting any intervention without confirming proper glenohumeral alignment could worsen a fracture-dislocation. 1

• In one comparative study, the axillary view failed to give the correct diagnosis in 8% of cases when compared to the scapular Y view, but both views together provide complementary information that maximizes diagnostic accuracy. 6

If Initial Radiographs Remain Equivocal

Proceed to CT Without Contrast

• Order a dedicated CT of the shoulder without contrast if the additional radiographic views don't clarify the finding, as CT better characterizes fracture patterns and can definitively identify posterior dislocations or subtle bony abnormalities. 1

• CT is particularly valuable for characterizing the "nonspecific bony structure" you're seeing—it could represent an avulsion fracture, a bony Bankart lesion, an osteochondral fragment, or even a normal anatomic variant like an os acromiale. 3, 7

• Consider CT angiography (CTA) if there are any signs of vascular compromise (diminished pulses, expanding hematoma, bruit), especially given the trauma mechanism, as axillary artery injury can occur with shoulder trauma and proximal humeral fractures. 1, 4

Critical Pitfalls to Avoid

• Never attempt shoulder manipulation or reduction without radiographic confirmation of the injury pattern—this could convert a stable fracture into a displaced one or worsen neurovascular compromise. 1

• Don't dismiss the finding as "nonspecific" without complete imaging—this exact scenario (incomplete views leading to missed posterior dislocation) is one of the most common medicolegal issues in shoulder trauma. 2

• Assess for neurovascular compromise thoroughly at initial presentation and after any intervention, as delays in recognizing vascular injury significantly worsen outcomes. 1

• In older patients (>40 years), maintain high suspicion for associated rotator cuff tears even if the bony injury is minor, as these are commonly overlooked and impact long-term function. 1

If All Imaging Confirms No Dislocation or Displaced Fracture

Consider MRI for Soft Tissue Evaluation

• If radiographs and CT show only the nonspecific bony finding without dislocation but pain persists beyond 2-3 weeks, obtain MRI without contrast to evaluate for labral tears, rotator cuff injury, or occult fractures. 3

• MRI is rated as "usually appropriate" (score 9/9) by the American College of Radiology for evaluating persistent shoulder pain when radiographs are noncontributory and soft tissue injury is suspected. 3

Physical Therapy Considerations

• Manual therapy directed at the cervicothoracic spine combined with specific exercises may benefit post-MVA shoulder pain, particularly if there's associated neck involvement, as demonstrated in whiplash-associated disorders. 8