Posterior dislocation in a voluntary subluxator: A case report

Purpose: Posterior instability of the shoulder is an uncommon occurrence. Its etiology has been classified as traumatic or atraumatic and its type as voluntary (individual can subluxate the shoulder posteriorly) or involuntary. Typically, patients with posterior voluntary instability do not have a history of trauma, can be treated successfully with physical therapy, and undergo surgery if the instability becomes symptomatic or develops an involuntary component. We present a patient with voluntary posterior subluxation who developed a symptomatic posterior instability after a traumatic event. Patient Presentation: This patient was unable to return to his preinjury function despite nonoperative interventions, including rehabilitation, and required operative treatment of his posterior labrum lesion. This patient had a rare combination of voluntary, atraumatic instability that coexisted with traumatic posterior shoulder instability. Conclusion: This case emphasizes the importance of recognizing this constellation of instability patterns and documents that traumatic posterior instability, even in the presence of preexisting voluntary posterior subluxations, may require operative intervention in young, active individuals.