Clinical History
A 35-year-old male presented with polytrauma, severe thoracic and head trauma, in a comatose state.
Imaging Findings
A 35-year-old male patient was referred to the emergency department of the hospital, after being involved in a high speed motor bike accident. He had severe head and thoracic trauma, and was in a
comatose state. The Injury Severity Score was 50 and the Glasgow score was 10. A total body CT-scan was performed, which showed brain swelling and diffuse axonal damage. Chest evaluation revealed a
subcutaneous emphysema, a right hydropneumothorax, consolidation of the right lower lobe, and the presence of an intrathoracic oval osseous structure. There was a comminuted fracture of the right
proximal humerus.
Discussion
The intrathoracic displacement of the humeral head is a very rare form of shoulder dislocation. It could be the extreme expression of the mechanism producing an inferior glenohumeral dislocation. A
review of the medical literature found less than twenty reported cases of fracture-dislocation of the humeral head with intrathoracic displacement. Usually, this condition is associated with a
fracture of the surgical neck, and a displacement into the homolateral hemithorax. A displacement into the controlateral hemithorax has also been described, and even a fracture of the proximal part
of the humerus with retroperitoneal displacement of the humeral head.The diagnosis is achieved with a CT-scan that enables the radiologist to demonstrate the associated lesions. These can be
subcutaneous emphysema, hemopneumothorax, or fractures of the ribs. The absence of vasculonervous injury being mentioned in the medical literature can be explained by the posterior mechanism of the
dislocation. In our case, the patient had severe associated lesions because of the high-energy trauma.The mechanism of this lesion is not completely clear. Most of the cases are related to a fall,
with the arm in a state of hyperabduction, with internal rotation and the elbow being in a locked position. Forces are transmitted through the long axis of the humerus towards the inferior aspect of
the joint capsule. This is the least resistant part, and results in an inferior glenohumeral dislocation as a consequence. One study suggested that this sudden abduction force was sufficient to both
fracture the humerus and drive the dislocated fragment into the thoracic cavity between the ribs. Others suggested that once the humeral head is led towards the thoracic cavity, the subcapital
fracture occurs after an adduction movement of the humeral shaft, made by the ribs, as a lever, and the rest of the body.
Differential Diagnosis List
Intrathoracic displacement of the humeral head.
Final Diagnosis
Intrathoracic displacement of the humeral head.
