INTRODUCTION: Posterior shoulder dislocation is a rare injury and represents 2-5% of all shoulder dislocation cases. Even less frequent , posterior fracture-dislocation represents 0.9 % of shoulder fracture dislocation. Mechanism of injury include a traumatic event with axial loading of the adducted , internally rotated arm or more commonly from violent muscle contraction following a seizure or electrocution injury. Delays in diagnosis it are common, estimating 50 % are missed and it can lead to chronic pain, stiffness and long-term functional disability. METHOD: A 44 years old male was brought to our emergency department following road traffic accident. He was riding a motorcycle when he was hit by car from the left side. He complained of severe pain and functional disability of his left shoulder. Radiographs revealed posterior shoulder dislocation (light bulb sign) with quiry greater tuberosity (GT) fracture. CT scan was performed to assess fracture displacement. U slab was then applied, and the patient was taken to operation theatre after a routine blood investigations. RESULT: The patient was placed in semi beach position under general anesthesia. Incision was made via transdeltoid approach. Intraoperatively, posterior dislocation of the humeral head was confirmed. GT fragment size 2.7 cm x 1.6 cmwas indentified and reduced with temporary Kirschner-wires. The reduction was confirmed under image guidance and final fixation achieved with two partially threaded 4.0 mm cannulated screws. The shoulder was then immobilized with a sling 2 weeks subsequently pendulum exercise and progressive range of motion exercise was started. DISCUSSION: Inadequate radiograph including axillary view and poor physical examination are the main factors of misdiagnosis.The physicalfindings that may present are shoulder locked in an internally rotated posititon with limited external rotation , prominent posterior shoulder and coracoid . Radiograph will showing positive rim sign , absence of the half-moon overlap , light-bulb sign, and the trough line. A delay in diagnosis and treatment of posterior shoulder dislocation or fracture-dislocation has increased risks of nonunion, subsequent humeral head collapse, avascular necrosis and post-traumatic arthritis. CONCLUSION: Posterior dislocation of shoulder associated with greater tuberosity fracture is a rare and frequently missed injury. A thorough clinical and radiographic evaluation should avoid the missed diagnosis. REFERENCES: Figueiredo A et al Posterior fracturedislocation of the shoulder: An often unrecognized traumatic injury Orthopedics, Traumatology and Sports Med Int Journal (2018) 1 :8-11
Frozen shoulder or missed posterior dislocation?
