To review, this is a 19 year-old female presenting with right shoulder pain after axial blow to the right shoulder.
Questions and Answers:
1) What are the findings on the initial radiographs?
The patient's axillary and AP films of the right shoulder are normal and show no evidence of fracture or dislocation. Her clavicle film also shows no evidence of fracture, but with close investigation of the medial aspect of her right clavicle, she does appear to have some asymmetry at the sternoclavicular junction when compared to the left clavicle. However, this asymmetry could easily be caused by film rotation or patient positioning and this film is by no means diagnostic.
2) What are the next steps in evaluation?
In any patient with significant mechanism, medial clavicle tenderness, and radiographs demonstrating sternoclavicular asymmetry, a posterior sternoclavicular dislocation should be considered. However, these dislocations can be difficult to diagnose using physical examination and radiographs, as many patients have overlying soft tissue swelling that inhibits palpation of bony deformities and the overlapping thorax, scapula, and lung apices can make appropriate visualization of the sternoclavicular joint challenging.
The serendipity view was developed specifically for assessment of sternoclavicular dislocations and is taken 40 degrees below perpendicular at the level of the clavicle. This radiographic view is very similar to the lordotic view, which was developed for evaluation of the lung apices.
Below is the above patient's lordotic/serendipity radiograph:
As you can see, there is a significant discrepancy between the medial clavicles, consistent with a likely posterior sternoclavicular dislocation. However, both lordotic and serendipity views are seldom obtained and easily misinterpreted, as sternoclavicular dislocations are rare and account for only 3% of shoulder girdle injuries.
Posterior clavicle dislocations are often associated with mediastinal structure injury or complication. The mean distance from the posterior aspect of the clavicle in its normal anatomic position and the brachiocephalic distance is only 6mm. In approximately 1/5 patients, a major artery, such as the carotid artery, aorta, or left infernal mammary artery) was even closer than the brachiocephalic. Because of the proximity of these vessels to the clavicle, a CT-angiogram should be obtained to assess for associated vessel dissection or thrombosis.
Prior to obtaining a CT-angiogram, imaging to confirm the true diagnosis of posterior sternoclavicular dislocation can be made using bedside ultrasound. Ultrasound is readily available and determination of anterior-posterior discrepancies between sternoclavicular joints is simple. See below image (from Bengtzen et al) in which the right clavicle (red arrow in image A) is clearly posterior to the sternum relative to the left clavicle (red arrow in image B).
3) What is the appropriate definitive management?
Approximately 30% of posterior sternoclavicular dislocations are associated with tracheal, esophageal, or neurovascular compression, and there is a 3-4% mortality rate. Given the proximity of major mediastinal vessels, a cardiothoracic surgeon should be present or available when orthopedic surgeons manipulate the sternoclavicular joint. The reduction should occur as soon as possible to prevent neurovascular injury, and is generally recommended to occur in the operating room in case of severe resultant vascular injury.
Sewell MD, Al-Hadithy N, Le Leu A, Lambert SM. Instability of the sternoclavicular joint: current concepts in classification, treatment and outcomes. Bone Joint J. 2013 Jun;95-B(6):721-31.
Bengtzen R, Petering R. Point-of-care Ultrasound diagnosis of posterior sternoclavicular joint dislocation. J Emerg Med 2017;52(4):513-15.
Groh GI, Wirth MA. Management of traumatic sternoclavicular joint injuries. J Am Acad Orthop Surg. 2001 Jan;19(1):1-7.
Ponce BA, et al. Sternoclavicular joint surgery: how far does danger lurk below? J Shoulder Elbow Surg 2013(7):993-999