title: Posterior dislocation in a voluntary subluxator: a case report.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors: Division of Sports Medicine and Shoulder Surgery, Department of Orthopedic Surgery, The Johns Hopkins University, Baltimore, MD 21224-2780, USA.
authors: Lara L
authors: LL
authors: Devgan
authors: Harpreet S
authors: HS
authors: Gill
authors: Christopher
authors: C
authors: Faustin
authors: Hyung Bin
authors: HB
authors: Park
authors: Edward G
authors: EG
authors: McFarland