Imaging in Sternal Fractures

Updated: Jan 11, 2016
  • Author: David A Fisher, MD; Chief Editor: Felix S Chew, MD, MBA, MEd  more...
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Overview

Overview

Sternal fractures are often seen in association with deceleration injuries and/or direct blows to the chest, and they occur in approximately 3% of patients suffering blunt chest trauma, such as in motor vehicle accidents, which account for the majority of sternal fractures (see the following images). [1] The introduction of seat-belt legislation has resulted in an increased frequency of these types of injuries. [2, 3, 4]

Lateral radiograph demonstrates complete dislocati Lateral radiograph demonstrates complete dislocation at the sternal angle. (Also see next image.)
Upright frontal radiograph in the same patient as Upright frontal radiograph in the same patient as in the previous image shows mild widening of the superior mediastinum after blunt trauma to the chest.

Most sternal fractures occur in the midbody, and they are typically transverse (see the first image above). Manubrial fractures are the next most common. Stress fractures are occasionally seen in athletes such as wrestlers, but they can also occur in women with osteoporosis and kyphotic thoracic spines.

These injuries can have an associated mortality rate of less than 1% [5, 6] as a result of associated chest injuries, such as cardiac contusion, aortic rupture, pulmonary contusion, and thoracic spine compression fractures.

Anatomy

The sternum has 3 parts: the manubrium, the body (corpus), and the xiphoid process (tip) (see the images below).

(Click Image to enlarge.) Posterior surface of the (Click Image to enlarge.) Posterior surface of the sternum.
(Click Image to enlarge.) Lateral border of the st (Click Image to enlarge.) Lateral border of the sternum.

The manubrium lies at the level of the third (T3) and fourth thoracic (T4) vertebrae. Along the superior margin of the manubrium is the suprasternal or jugular notch. Both the clavicle and the first rib articulate with the manubrium, and the sternal head of the sternocleidomastoid muscle inserts onto this portion of the sternum.

The joint between the manubrium and the body, the manubriosternal joint, forms the sternal angle, which is at the level of the second rib. In older people, this joint tends to be fused.

The xiphoid process is cartilaginous in younger people and ossified in older people

Preferred examination

The routine radiologic study of the sternum consists of a lateral projection and frontal views, which are obtained with the patient prone and rotated slightly off the midline in each direction. Normal anatomic variants, such as nonunited ossification centers, may sometimes cause a diagnostic dilemma. Initially, computed tomography (CT) scan studies were less sensitive than plain radiographs. However, the newer generation of multidetector-row CT (MDCT) scanning units now allow for multiplanar and 3-dimensional (3-D) reconstruction, which greatly improve accuracy. CT scanning provides superior sensitivity and specificity but at greater cost and with increased radiation exposure. Ultrasonography has been proven to be as accurate as radiography in diagnosing sternal fractures. However, lateral radiographs remain the standard means of demonstrating the grade of sternal displacement. [3, 7, 8, 9, 10, 11]

Trauma to the aorta and cardiac and/or pulmonary contusions are part of the differential diagnosis.

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Radiography

The lateral radiograph is usually the most valuable view for detecting sternal fractures and for determining the degree of displacement (see the following images). [12]

Lateral radiograph of the normal sternum. Lateral radiograph of the normal sternum.
Frontal radiograph of the normal sternum. Frontal radiograph of the normal sternum.
Lateral radiograph demonstrates complete dislocati Lateral radiograph demonstrates complete dislocation at the sternal angle. (Also see next image.)
Upright frontal radiograph in the same patient as Upright frontal radiograph in the same patient as in the previous image shows mild widening of the superior mediastinum after blunt trauma to the chest.
Supine frontal radiograph after significant blunt Supine frontal radiograph after significant blunt trauma to the anterior chest wall shows marked mediastinal widening. (Also see next image.)
Lateral radiograph shows a complete displaced frac Lateral radiograph shows a complete displaced fracture of the sternum (arrow) (same patient as in the previous image above).

Almost all patients with sternal fractures complain of localized sternal pain. Therefore, correlation with the clinical presentation is important.

Nonunited ossification centers and failure of bony fusion of the sternomanubrial and sternoxiphoid articulations can simulate fractures; the angulation is variable at both of these sites.

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Computed Tomography

CT scan studies were initially less sensitive than plain radiography. [13] The newer generation of MDCT scanning units now allow for multiplanar and 3-D reconstruction, which greatly improve accuracy. CT scanning provides superior sensitivity and specificity but at a greater cost and with more radiation exposure.

CT scanning is particularly useful to assess patients with sternal fractures for associated injuries such as pulmonary contusion, pneumothorax, or retrosternal hematoma.

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Ultrasonography

Ultrasonography is a useful way to demonstrate fractures of the sternum. [14, 15, 16]  The sensitivity of ultrasonography is comparable to that of plain radiography, but conventional radiography remains the standard means of documenting a sternal fracture.

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Nuclear Imaging

Nuclear bone scanning may be needed if the initial radiographic findings are not definitive (see the following image).

Nuclear bone scan of fractures of the sternum (arr Nuclear bone scan of fractures of the sternum (arrow) and of the ribs on the right side (arrowheads).

Total-body bone scans are sensitive for acute sternal trauma. However, the anatomic detail is limited, and correlation with the results of radiography or CT scanning is often necessary.

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