Posterior Shoulder Dislocation During Morning PT: A Case Report

Abstract

Posterior shoulder dislocation should be considered in the differential diagnosis of acute shoulder pain and immobility following trauma. Although far less common then the anterior dislocation, it is associated with high rates of comorbidity. Seventy-nine percent of posterior shoulder dislocations are missed on initial presentation, which is partially responsible for the high rate of comorbidity associated with these injuries. The mechanism of injury is varied from generalized seizure to minor trauma, which adds to the complexity of the diagnosis. There is a well-documented "vulnerable position" described as injury to the arm while it is in a flexed, adducted, and internally rotated position that is highly associated with posterior shoulder dislocation. The plain film scapular Y is the most clinically significant imaging and can be used alone to diagnose the injury, although ancillary imaging such as magnetic resonance imaging is often warranted. Once this rare condition has been diagnosed, there are a number of appropriate reduction techniques available to the health care provider. Presented here is a case of posterior shoulder dislocation that occurred while doing pushups for routine morning physical training. Also discussed are keys to recognition and treatment as well as a brief discussion of associated complications of the injury.

Posterior Shoulder Dislocation: A Rare Case Report and Review of the Literature

“…In a normal shoulder, this view shows the humeral head lying at the center of a "Y" shape, formed by the intersection between the coracoid process and acromion superiorly and the scaphoid body inferiorly. The posterior displacement of the humeral head to the anatomical "Y" position is seen among individuals with PSD [2]. Axillary view offers a great visualization of the glenoid to evaluate possible fracture from the impaction of the humeral head into its surface [12].…”

“…Most clinicians (60-79%) failed to establish an accurate diagnosis of PSD on initial examination [1]. The high incidence of complications from this injury makes early detection important in preventing long-term comorbidities [2]. Posterior shoulder dislocation is classified into the simple type and complex type.…”