Sternal Fracture

Both PSF and ISF commonly result from blunt chest trauma sustained in motor vehicle accidents or falls [1]. Less frequently, patients present with SF after other forms of accidents or assault. About 75% of those cases correspond to PSF, only 25% to ISF. Besides blunt trauma, distinct pathologies may lead to SF. In detail, osteoporosis and severe thoracic kyphosis predispose for this lesion [3]. Postmenopausal women, elder patients as well as those receiving long-term corticosteroid therapy are at particularly high risks [4]. In this context, ISF is much more common than PSF.

Midline chest pain is the single most important symptom of any SF. It may be the only symptom, especially in ISF patients [4]. SF may be accompanied by retrosternal or mediastinal hematoma, and affected individuals may experience symptoms of blood loss and hemodynamic instability. Hematomas may also compress vital structures in the thoracic cavity, thereby interfering with heart and lung function [5].

Few SF are palpable.

PSF patients may additionally suffer from symptoms associated with:

• Rib fractures
• Flail chest
• Pulmonary contusion
• Pneumothorax
• Blunt cardiac injury
• Aortic rupture and other vascular injuries
• Hemothorax
• Ruptured diaphragm

Anamnestic data usually imply a patient to have sustained thoracic trauma. In such cases, extensive injuries may indicate the need to assure proper ventilation and cardiovascular function before taking diagnostic measures to assess the integrity of the sternum. Distinct imaging techniques may be applied to this end:

• Sonography has been shown to yield reliable results, is readily available and cost-effective [6].
• While anterior-posterior chest radiographs are of low sensitivity regarding the detection of SF, lateral sternal views often allow for the respective diagnosis [7]. Lucent fracture lines indicate the site of the lesion; displacement of bone fragments may be observed.
• Computed tomography may be required to depict SF that cannot be visualized by means of plain radiography and according to recent studies, this applies to the majority of minor SF [8]. However, computed tomography scans are associated with considerable exposure to ionizing radiation. Distinct algorithms have been developed to aid in the decision of whether blunt trauma evaluation should or should not comprise computed tomography scans [9] [10].

Additional studies are indicated to identify the underlying disease in patients presenting with pathological SF [3] [4] [11] [12].

The sternum is commonly referred to as the breastbone and forms part of the thoracic wall. It is located in the center of the chest with its most cranial portion, the manubrium forming the sternoclavicular joints with the clavicles. Along the sternum's body, a total of fourteen sternocostal articulations connects the breastbone with seven true ribs on either side. Finally, the inferior portion of the sternum, the xiphoid process, constitutes the site of insertion of the costoxiphoid ligaments, tendons of the diaphragm, and determined abdominal muscles. Either part of the sternum may succumb to the impact of mechanical forces that exceed the maximal resistance of the breastbone, and the respective patient sustains a sternal fracture (SF).

As a whole, the rib cage provides mechanical protection to major blood vessels, mediastinal organs and vital thoracic organs like lungs and heart. Its physical integrity may be disrupted if a patient sustains thoracic trauma and due to the afore-described proximity of the sternum to other bones and organs, an individual suffering from SF commonly presents with additional fractures or lesions of internal organs. This condition may be referred to as polytrauma sternal fracture (PSF) and differs largely from the isolated sternal fracture (ISF) regarding clinical presentation, workup, and treatment [1].

In PSF patients, the outcome largely depends on the severity of accompanying injuries. ISF patients have an excellent prognosis and usually, recover within weeks [2].

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