Retrosternal dislocation of the clavicle:
A case report
C. PAPAGEORGIOU, E. VASILIADES, C.VRADELIS
Department of Orthopaedics, General Hospital of Drama, Greece

ABSTRACT
The retrosternal dislocation is an extremely rare injury. We describe a case, in terms of diagnosis, management and potential risk for the patient. The dislocation was successfully reduced, five days postinjury, by a closed method, under general anesthesia. The diagnosis was established by specific sternal x-rays and computer tomography. This entity can be early recognized and treated in proper time, with excellent results.

Key words: Dislocation, clavicle, sternoclavicular

INTRODUCTION
Retrosternal dislocation is extremely rare. Fewer than 110 cases were found in the literature, since Sir Astley Cooper first described a case in 1824[12].
Diagnosis is often difficult but can have serious consequences if missed, while the term "stealth" dislocation is apt[2]. His interest focused on potential serious complication, arriving from laceration of vital structures of the mediastinum, such as the subclavian artery, carotid and internal mammary vessels, the dome of the pleura, the trachea and the esophagus. The brachial plexus may be injured as well[1,13].
We present a case of a successful closed reduction of a retrosternal dislocation of the clavicle, five days postinjury. We recommend early diagnosis and treatment in order to avoid serious and dangerous complications.

CASE REPORT
A 26 years old man had an injury of his left sternoclavicular joint, in a car accident. The diagnosis was not made during the patient’s transfer to the emergency department, but 2 days later, during his hospitalization.
Clinically, the anterosuperior fullness of the chest, which is produced by the clavicle, was less prominent in the left side than in the right. The head was tilt toward the left side and discomfort was increased when the patient was placed in the supine position and during the abduction of the affected shoulder.
Diagnosis was made by special radiographic projection (Serendipity view) and was confirmed by computer tomography[12], (figure 1,2).
The reduction of the dislocation was successfully done, in the operation room, under general anesthesia, five days post injury. It was performed by the Abduction-Traction Technique[1,12] and was confirmed by the same imaging modalities (figure 3,4). At the 18-month follow up, the patient had no complaint of discomfort. He presented a completely normal shoulder position and shoulder girdle motion.

1. 2.
Figure 1. Posterior dislocation of the left sternoclavicular joint, as seen on a 40-degree cephalic tilt radiograph (Serendipity view). The left clavicle is dislocated inferior to the horizontal line drawn across the superior border of the normal right clavicle.
Figure 2. Computed tomogram revealing a left posterior sternoclavicular joint dislocation as a result of impact of the posterolateral point of the unilateral shoulder, during a car accident. Note the degree of displacement of the posterior medial end of the clavicle to the esophagus.

3. 4.
Figure 3. Same radiograph projection, "Serendipity view", after the reduction.
Note the normal position of the left sternal end of the clavicle, in relation to the normal side.
Figure 4. Computed tomogram after the reduction. Note the normal position of the sternal end of the left clavicle and the normal relations to the structures of the mediastinum.

DISCUSSION
The diagnosis of the retrosternal dislocation of the clavicle is difficult. In addition to that, because of its location and its vicinity to the vital structures of the mediastinum, this injury can be serious and dangerous.
The local swelling eliminates the contour of the sternal end of the clavicle. The plain anteroposterior radiograms may appear normal, while the patient presents respiratory distress, dysphagia and symptoms from the brachial plexus compression[3,12].
Patients should be examined in both shoulders and special radiographic projections (Serendipity views) may be required[6,7,12]. The method of choice is computerized axial tomography9.
This injury complex mainly occurs as a result of an indirect force applied to the posterolateral aspect of the shoulder. We found that the most common cause of this injury is vehicular accidents with a frequency of 40%, while sport accidents account for approximately 21%[4,13].
Close reduction can be successfully done within the first 48 hours, resulting in a stable sternoclavicular joint. Open reduction is indicated when closed method is impossible or the joint is unstable[2,10,13]. In open reduction and transfixion of the sternoclavicular joint, it is of paramount importance that metallic pins, as well as Kirschner wires or Steinmman pins, should be avoided, because they all have been reported to migrate, either intact or broken and cause serious complications, including death[9,11,14]. In addition to that, it is recommended that medial clavicular epiphysis fuses with the shaft of the clavicle around the 23rd to 25th year of age. It is believed that many so-called sternoclavicular joint dislocations are not dislocations at all, but injuries of the medial physis of the clavicle. The majority of these injuries will heal with time, without surgical intervention[5,15].

CONCLUSION
The retrosternal dislocation is a problem of emergent medical practice. We came to the conclusion that the high index of suspicion and the knowledge of anatomy of the area, in addition to the early diagnosis and proper management, prevent the serious complications of this rare injury.

REFERENCES
1. Buckrfield C., Castle M. Acute Traumatic Retrosternal, Dislocation of the Clavicle. JBJS. 1984; 66A, 3, 379-85.
2. Cale W.D., Dunn S., McPherson, Oni H. Retrosternal Dislocation of the Clavicle: the Stealth Dislocation. Injury. 1992; 93, 8, 563-4.
3. Elting J.I. Retrosternal Dislocation of the clavicle. Arch Surg. 1972; 70A, 1251-8.
4. Gazak S., Davidson S.J. Posterior Sternoclavicular Dislocation. Two Case Reports. J Trauma. 1984; 24, 80.
5. Grand J. CB Method of Anatomy. 7th ed Baltimore Williams and Wilkins. 1965.
6. Heining C.F. Retrosternal Dislocation of the clavicle, Early Recognition, X-Ray Diagnosis and Management. JBJS. 1968; 50A, 830.
7. Hobbs D.W. Sternoclavicular Joint. A New Axial Radiographic View. Radiology. 1968; 90, 801.
8. Leonard J.W., Gifford R.W. Migration of a Kirschner Wire from the Clavicle into Pulmonary Artery. Am J Cardiol. 1965; 16, 598.
9. Levinsohn E.M., Bunnell W.P., Vuan H.A. Computer Tomogram in the Diagnosis of Dislocation of the Sternoclavicular. Joint Clin Orth. 1979; 140, 12.
10. Lukas G.L. Retrosternal dislocation of the clavicle. JAMA. 1965; 193, 850.
11. Lyons F., Rockwood C. Migration of pins used in operations on the shoulder. JBJS. 1979; 72A, 8, 1262-7.
12. Rokwoood C., Green M. Fractures in adults. 4th ed. Lippincott Raven. 1996; 980.
13. Wirth M., Rockwood C. Acute and chronic traumatic injuries of the sternoclavicular joint. JAAOS. 1996; 4, 5, 268-78.
14. Worman L.W., Leagus C. Intrathoracic injury following retrosternal dislocation of the clavicle. J Trauma. 1967; 7, 416.
15. Zaslar K.R., Ray S., Neer C.S. Conservative management of a displaced medial clavicle physeal injury in an adolescent athlete. J Sports Med. 1989; 17, 6, 83.

Mailing address:
Dr Kosmas Papageorgiou
Department of Orthopaedics, General Hospital of Drama
Hippocratous Rd, PO Box 66100 Drama Greece
5 Averof str, PO Box 66100 Drama, Greece
Tel: +30 0521 031563, Fax: +30 0521 031563
E-mail: kosmasp@otenet.gr