Fracture, Sternal

Article Author:
Thomas Bentley
Article Editor:
Jonathan Journey
Updated:
11/1/2018 12:28:20 PM
PubMed Link:
Fracture, Sternal

Introduction

Sternal fractures are most commonly caused by blunt, anterior chest-wall trauma and deceleration injuries, with a reported incidence of 3% to 6.8% in motor vehicle collisions. Athletic injuries, falls, and assaults are the frequent causes of the remaining cases. Sternal fractures are frequently diagnosed using a lateral chest x-ray or CT scan of the chest. Sternal fractures increase the risk of and are commonly associated with other injuries. The disposition of patients with a sternal fracture is dependent upon several variables, including potentially significant associated injuries, comorbidities, and inadequate pain control.[1][2]

Etiology

Anterior, blunt chest trauma is the most frequent cause of sternal fractures. Cardiopulmonary resuscitation, athletic injuries, falls, and assaults result in the majority of the remaining traumatic cases. Patients with severe thoracic kyphosis, osteoporosis, or osteopenia can develop insufficiency fractures of the sternum. Patients on long-term steroid therapy, postmenopausal women, and elderly patients are at increased risk. Stress fractures of the sternum have also been reported secondary to repetitive upper body use in such sports as weightlifting and golf.[3]

Epidemiology

Sternal fractures are the result of motor vehicle collisions in 60% to 90% of cases. This is typically the result of the chest striking the steering wheel with most injuries occurring in older vehicles with no airbag deployment. Fractures are slightly more prevalent in females than males. Sternal fractures are more common in older patients, and this is thought to be due to the more elastic chest wall of younger patients. Younger patients are more likely to incur intrathoracic injury because the energy of impact is not as like to be absorbed by the sternum. Sternal fracture occurrence has tripled with the use of vehicular shoulder restraints, likely secondary to the deceleration forces concentrated directly to the sternum.[4][5]

Pathophysiology

The majority of sternal fractures result from blunt trauma. The most common location of the fracture is in the manubrium or the body. In many cases, there is an underlying organ injury. Heart and lung contusion, as well as rib fractures, are not uncommon with sternal fractures. The pain can be moderate to severe and limit deep inspiration, leading to atelectasis. Myocardial injury can lead to pericardial effusions resulting in tamponade.

History and Physical

Sternal fractures are most commonly caused by blunt anterior chest wall trauma and deceleration injuries. Motor vehicle collisions, athletic injuries, falls, and assaults are the most frequent causes.

Anterior chest wall pain is typically present with sternal fractures. Shortness of breath has been reported in up to one-fifth of cases. Deep breathing and coughing may aggravate pain. Pain reported in sternal stress fractures or acute insufficiency fractures may mimic other serious medical conditions as there is no obvious mechanism of injury and the pain is typically more diffuse.

Point tenderness over the sternum is frequently present in sternal fractures. Soft tissue swelling, ecchymoses, or palpable deformity may also be present in approximately half of the reported cases. Fracture-related crepitus may be present upon palpation.

Assessment for other associated injuries is paramount, including rib fractures, flail chest, sternoclavicular dislocation, pneumothoraces, hemothoraces, cardiac tamponade, myocardial contusion, pulmonary contusion, intra-abdominal injuries, spinal compression fractures, as well as other traumatic injuries.

Evaluation

Chest radiographs are frequently obtained in patients with a suspected sternal injury. The anteroposterior radiograph has been shown only to be 50% sensitive for detecting sternal fractures. A lateral radiographic view increases the sensitivity, and is typically diagnostic, as most sternal fractures are transverse and any displacement occurs in the sagittal plane.[2][6]

CT of the chest is commonly obtained in patients where a high index of suspicion of sternal fracture exists. Axial CT scan may be less sensitive than plain radiographs, as CT cuts may miss transverse sternal fractures. Spiral CT scan is likely to be most sensitive, but no gold standard exists. CT of the chest is also advantageous to rule out associated injuries secondary to sternal fractures.

Ultrasonography has been shown to detect sternal fractures with equal or greater sensitivity than plain radiography. Time to diagnosis may be significantly reduced with bedside ultrasonography, however limiting factors including inter-operator variability must be taken into account.

Cardiac monitoring and pulse oximetry should be obtained in all patients with sternal fractures while in the emergency department. Electrocardiograms should be performed, evaluating for signs of myocardial contusion. Arrhythmias, conduction disturbances, sinus tachycardia, or ST-segment changes may be present. Enzyme markers of cardiac injury may be useful if cardiac contusion is suspected, with troponin elevation being found to be highly specific for myocardial injury. Echocardiography also aids in the detection of myocardial contusions, with a direct view of wall motion abnormalities.

Treatment / Management

Patients with acute sternal fractures should be managed using ATLS guidelines. After the patient's airway, breathing, and circulation have been evaluated, a primary survey assessing any life-threatening conditions should be performed. An associated injury such as tension pneumothorax, hemothorax, cardiac tamponade, and flail chest should be immediately identified and treated. Upon stabilization, a secondary survey should be performed. Rib fractures, pulmonary contusions, and blunt myocardial injury are among the many chest injuries associated with sternal fractures which can be managed at this stage.[7][8]

Electrocardiography and cardiac monitoring should be obtained in patients with sternal fractures. Patients with signs of myocardial contusion should be admitted for further evaluation and management. Patients with associated intrathoracic injuries, hemodynamically instability, uncontrolled pain, should also be admitted for observation. It is also recommended that elderly patients be observed closely as these patients are at higher risk for respiratory issues.

Adequate analgesia is the mainstay of treatment for isolated sternal fractures. Admission for isolated sternal fractures is generally not necessary provided no concerns are identified during the clinical evaluation. Patients should follow up with her primary care physician within the first 24 hours. Deep breathing exercises are recommended to avoid pulmonary complications during recovery.

For significantly displaced or unstable fractures, operative fixation may be necessary. Most isolated sternal fractures, however, will heal spontaneously over the average course of 10 weeks.

Differential Diagnosis

The differential diagnosis of acute sternal injury is broad. Rib fractures, flail chest, sternoclavicular dislocation, pneumothoraces, hemothoraces, cardiac tamponade, myocardial contusion, pulmonary contusion, intra-abdominal injuries, spinal compression fractures, as well as other traumatic injuries must be ruled out.

Prognosis

Isolated sternal fractures have an excellent prognosis, with an overall mortality rate of 0.7%. Most patients with these solitary injuries recover completely over the average reported 10 weeks. Surgical fixation can be performed in rare cases of chronic sternal pain or nonunion. Up to two-thirds of sternal fractures have associated injuries, with mortality ranging from 25% to 45% in these cases.

Complications

Complications from sternal fractures are frequently due to associated injuries. Displaced or unstable sternal fractures result in an increased risk of pulmonary injuries, pericardial effusions, rib fractures, and spinal compression fractures.

Chest pain after the injury can persist for 8 to 12 weeks. Pain with inspiration can result in atelectasis, pneumonia, and other pulmonary complications.

Sternal fracture nonunion, false joint, and overlap deformities are rare. These complications may require delayed surgical repair. Advanced age, osteoporosis, prolonged steroid use, and diabetes increase the risk for delayed union.

Osteomyelitis, sternal abscess, and mediastinitis are rare. Large hematoma formation, intravenous drug abuse, and a staphylococcal infection elsewhere increase the risk of these infectious complications.

Enhancing Healthcare Team Outcomes

Sternum fracture is not an uncommon injury. The majority of these patients present to the emergency department and often require close monitoring in an ICU setting. Hence, nurses should be familiar with the management of this fracture and its potential complications. In most patients with a sternal fracture, the outcome is excellent. Recovery may take 4-6 weeks. The rare patient may develop chronic pain or nonunion. An isolated stable sternal fracture can be managed with conservative care, whereas those who have an unstable sternum usually require surgical fixation. In the elderly, the recovery may be prolonged because of pain and osteoporotic bone. These patients should be encouraged to join a physical therapy program to regain their strength and muscle mass. [9][10]