Continuing Education Activity

Sternal fractures have a reported incidence of 3% to 6.8% in motor vehicle collisions, as they are most commonly caused by blunt chest trauma. These fractures are frequently evaluated using a lateral chest X-ray or CT scan of the chest. This activity outlines the evaluation and treatment of sternal fractures and describes the role of the interprofessional team in providing superior care to those with this injury.

Objectives:

• Identify the epidemiology of sternal fractures.

• Evaluate a patient with a sternal fracture.

• Determine the treatment options for a sternal fracture.

• Communicate the importance of cooperation among the interprofessional team members in managing this fracture and the steps to avoid complications for those with this condition.

Introduction

Sternal fractures most commonly result from 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. Clinicians frequently diagnose sternal fracturesABBA 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 most 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 result from motor vehicle collisions in 60% to 90% of cases. They typically result from 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, which appears 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 the impact is not as likely 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 sternal manubrium or 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

The most common causes of sternal fractures are 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 is a presenting symptom in up to one-fifth of cases. Deep breathing and coughing may aggravate pain. The 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.

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

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

Evaluation

Chest radiographs are usually the initial imaging in patients with a suspected sternal injury. The anteroposterior radiograph is only 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 another common diagnostic test in patients with a high index of suspicion of sternal fracture. An axial CT scan may be less sensitive than plain radiographs, as CT cuts may miss transverse sternal fractures. A spiral CT scan is likely the most sensitive, but no gold standard exists. CT of the chest is also advantageous in ruling out associated injuries secondary to sternal fractures.

Ultrasonography can detect sternal fractures with equal or greater sensitivity than plain radiography. Bedside ultrasonography may significantly reduce the time to diagnosis; however, limiting factors, including inter-operator variability, must be considered.

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

Treatment / Management

Clinicians should employ advanced trauma life support (ATLS) guidelines to manage patients with acute sternal fractures. After the patient's airway, breathing, and circulation have undergone evaluation, a primary survey assessing any life-threatening conditions should follow. The clinician should identify and treat any associated injury, such as tension pneumothorax, hemothorax, cardiac tamponade, and flail chest. Upon stabilization, a secondary survey should take place. Rib fractures, pulmonary contusions, and blunt myocardial injury are among the many chest injuries associated with sternal fractures, which are manageable at this stage.[7][8]

Electrocardiography and cardiac monitoring are necessary for patients with sternal fractures. Patients with signs of myocardial contusion require admission for further evaluation and management. Patients with associated intrathoracic injuries, hemodynamically unstable, or uncontrolled pain should also be admitted for observation. It is also recommended that elderly patients receive close observation as these patients are at higher risk for respiratory issues.

Adequate analgesia is the mainstay of treatment for isolated sternal fractures. Admission is generally unnecessary, provided there are no identified concerns during the clinical evaluation. Patients should follow up with their primary care physician within the first 24 hours. Deep breathing exercises can help patients avoid pulmonary complications during recovery.

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

Differential Diagnosis

The differential diagnosis of an 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 ten weeks. Surgical fixation is necessary 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 on 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 a 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.

Deterrence and Patient Education

The clinical staff should help the patient understand the mechanism and severity of their injury, encourage compliance with all medication and therapy regimens (both nonsurgical and postsurgical), and provide lifestyle assistance on things such as comfort during sleep, limitations on activity, and indications that they need to contact the clinician's office.

Enhancing Healthcare Team Outcomes

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