Sternal Fracture

Most sternal fractures are caused by blunt anterior chest trauma, although stress fractures have been noted in golfers, weight lifters, and other participants in noncontact sports. Insufficiency fractures caused by abnormally decreased bone density or weakened bone can occur spontaneously in patients with osteoporosis or osteopenia (particularly in older persons, especially women), those on long-term steroid therapy, or those with severe thoracic kyphosis. Cardiopulmonary resuscitation commonly causes rib and sternal fractures, something that must be considered during the recovery process from the illness that led to the cardiac arrest.

Fractures usually occur at the body or the manubrium. In one study of 79  patients with sternal fracture, 13 (16.5%) had a fracture of the manubrium, 10 caused by seat-belt injury. In 3 cases, stabilization was performed, and follow-up showed sufficient consolidation without complications.[11]

(Surface anatomy of the sternum is shown in the illustration below.)

Motor vehicle collisions account for 60-90% of sternal fractures.[12] Most of these are in older vehicles in which a seat belt is used but no airbag deploys.[13] Those who are unrestrained generally sustain injury from ejection from the vehicle or impact with the steering wheel or dashboard. Direct impact sports, falls, vehicle-to-pedestrian accidents, and assaults account for most of the rest. Spontaneous fractures and stress fractures are rare. Occurrence of sternal fracture has tripled with the use of vehicular shoulder restraints, likely secondary to deceleration forces concentrated directly to the sternum.[14]

Sternal fractures are slightly more common in females than in males, possibly because of shoulder restraint positioning; however, the difference is small. Sternal fractures are more common in patients older than 50 years, possibly because of a weaker or inelastic bony thorax. Because of the elasticity of their chest walls, children less commonly have sternal fractures; however, when present, the underlying injuries may be more severe.[15, 16, 17, 18]

Because of the lack of substantial change in size or shape of the sternum between ages 30 and 100 years, the increased incidence of sternal fracture in the elderly may be the result of cortical thickness or bone mineral density changes in the sternum, as opposed to changes in morphology.[13]

The prognosis is excellent for isolated sternal fractures. Most patients recover completely over a period of several weeks. In the absence of other injuries or severe pain, patients with isolated sternal fractures do not need admission to hospital.[19]  In rare cases of nonunion and chronic sternal pain, surgical fixation can be considered.

The mortality rate from isolated sternal fracture is extremely low. Mortality associated with sternal fracture is 0.7%. Death and morbidity are related almost entirely to associated injuries, such as aortic disruption, cardiac contusion, and pulmonary contusion, or to unrelated injuries to the abdomen or head sustained in the accident, with reported mortality of 25-45%.[19]

In most cases of sternal fracture, consider the diagnosis based on the mechanism of injury. Direct trauma is the most common cause of injury due to mechanisms such as motor vehicle accidents, sports, and falls. Hyperflexion injuries can lead to sternal fractures, often in association with spinal column injuries.[1, 2, 3]

The symptoms in a patient with spontaneous insufficiency or stress fracture create a greater diagnostic challenge unless the diagnosis is considered carefully, because the symptoms often resemble other serious conditions. These fractures tend to occur in the elderly population, especially in postmenopausal women.

Almost all patients complain of localized sternal pain. Pain may be more diffuse in patients with insufficiency fractures and may lead to a more extensive differential diagnosis for chest pain in older persons.

Dyspnea is present in 15-20% of these patients and may indicate associated cardiopulmonary contusion.

Palpitations may be noted only if dysrhythmia occurs, which is unusual in isolated sternal injury without associated cardiac contusion.

Carefully assess for signs of other potentially associated injuries in addition to sternal fracture. These may include rib fractures, flail chest, pneumothorax, hemothorax, pulmonary contusion, blunt cardiac injury (manifested by dysrhythmias or murmurs), pericardial tamponade, or vascular injury, as well as head, neck, abdominal, or extremity trauma.

Pain is usually localized over the fracture site and readily reproducible, though patients with insufficiency fractures may have more diffuse pain. Crepitation or displacement is not often palpable unless the sternum is disrupted completely with significant instability of the fragments.

Anterior chest wall pain is typically present with sternal fractures. Shortness of breath is a presenting symptom in up to 20% of cases. Deep breathing and coughing may aggravate pain.[14]

Only 40-55% of patients have overlying soft-tissue edema or ecchymosis. Patients with insufficiency fractures usually exhibit an exaggerated dorsal kyphosis.

Radiographs

Chest radiographs are usually the initial imaging provided for patients with suspected sternal injury.[14]  Although standard posteroanterior and lateral chest radiographs may reveal fracture, sternal views are necessary if injury is suspected from physical examination.

Be aware of normal ossification centers that normally close by the late teenage years, though sternomanubrial and sternoxiphoid centers may never fuse in 10-30% of patients.

Sternal views enhance visualization of the sternum, since they change the angle and focus of the exposure. Obtain these views if highly suspicious for injury and no fracture is seen on chest radiograph.

Ultrasonography

Ultrasonography demonstrates sternal fractures with as much sensitivity as plain radiography. Ultrasound is not accurate in identifying the degree of displacement of sternal fractures, but it can accurately identify related hematomas and pleural effusions.[6]

Normal sternal development should be considered when evaluating the sternum in children. Each component of the sternum contains several ossification centers. Their pattern of appearance and configuration may vary greatly with the age of the patient. Since some ossification centers are discernible until adulthood, they may be misinterpreted as a fracture in childhood. Failure of midline fusion may also be confused with a fracture.[23]  

Bedside ultrasonography has been demonstrated in a study to be more effective than conventional radiography in making the diagnosis of sternal fracture.[24]  Diagnosis time may be significantly shortened by the use of bedside ultrasonography.[25]

CT scanning

CT is the most common imaging study to make the diagnosis.[26, 27]  Of 292 patients with sternal fracture in one study, 94% of fractures were visible only on chest CT. Cardiac contusion was identified in 7 of the patients.[28]

CT scanning may reveal sternal fracture, but it is less sensitive than plain radiography, as the fracture may be positioned between image cuts.

CT scans may demonstrate retrosternal hematoma; although its specificity is high, its sensitivity is poor.

Suspicion for other chest injuries warrants CT scans.

In general, laboratory studies are not indicated for evaluation of isolated sternal injuries, though consider appropriate laboratory studies in evaluation of potential associated injuries. Creatine kinase (CK)-MB index and other enzyme markers of cardiac injury (troponin) are helpful if cardiac contusion is suspected. However, the routine use of this test is not indicated. Remember that total CK may be elevated from other noncardiac muscle injuries.

Obtain an ECG in all patients with significant blunt injury to chest. Findings indicative of cardiac contusion include dysrhythmia, conduction disturbances, or ST-segment changes consistent with myocardial injury.

Perform cardiac monitoring as workup proceeds until making a disposition decision for the patient.

Obtain pulse oximetry on all patients during their evaluation.

Do not routinely consider echocardiography in patients with isolated sternal injury. Studies have shown that up to 25% of patients with sternal fracture have small pericardial effusions, yet, in the absence of hemodynamic compromise, this requires no further intervention.

A repeat ECG in 6 hours is recommended and requires no further workup for cardiac injury if the findings are normal.[29, 30]

Although no evidence specifically links sternal fractures to abuse in this age group,[16]  such injuries are unusual injuries in children. Just like long bone fractures and rib fractures, sternal fractures should heighten the suspicion of child abuse. Sternal fractures are also more difficult to recognize on radiographs in the pediatric population and should be suspected if deformity, crepitus, and significant pain are present.

Chronic nonunion of sternal fractures is typically treated by osteosynthesis plating with or without autologous bone grafting.[31]

Initiate basic or advanced trauma care based on the level of training of the ambulance crew and initial assessment.

Care should include the following steps:

• Supplemental oxygen
• Cardiac monitoring
• Intravenous access
• Consideration of an analgesic
• Trauma care as warranted by protocol for any suspected associated injuries

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.[14]  After immediate stabilization, evaluate the patient by obtaining a complete history and physical examination.

Taping or splinting of sternal fractures is contraindicated, as restriction of normal chest expansion during respiration can lead to atelectasis and pulmonary insufficiency.

Adequate analgesia is the treatment of choice, both during initial care and subsequently during the recovery period.[32, 33]

Encouragement of deep breathing decreases pulmonary complications during recovery.

Patients with signs of myocardial contusion require admission for further evaluation and management. Patients with associated intrathoracic injuries, hemodynamically instability, or uncontrolled pain should also be admitted for observation. It is recommended that elderly patients receive close observation, as these patients are at higher risk for respiratory issues.[14]

Consult a trauma surgeon when serious associated injury is diagnosed or suspected.

 

 

Numerous studies demonstrate that admission for isolated sternal fracture is not generally necessary unless associated injuries or social situations require such considerations.[34, 35, 36, 37]

One study suggests that patients with pain that is difficult to control with outpatient analgesics should be considered for admission and be given a continuous infusion of an anesthetic via a subperiosteal catheter.[38] Improved respiratory function was noted with this technique; however, it may not be readily available at most sites.

Consider at least an observation admission for elderly persons with chest wall fractures, because these patients are at increased risk for respiratory compromise and atelectasis. In older people, provide adequate analgesia; however, consider that a patient's baseline level of independent function may be compromised by adequate analgesics. Consider appropriate arrangements for assistance. Consideration for admission is supported by current trauma literature.

During pregnancy, shield the abdomen and pelvis with a lead apron prior to obtaining required chest radiographs. NSAIDs for analgesia are contraindicated outside the first trimester, though several category B opiate combinations exist for pain management.

Surgical care

Surgical fixation for sternal fractures is generally unnecessary, although a study has suggested that a more rapid recovery can be made if painful unstable fractures are fixated early rather than allowing them to heal over time.[35, 39, 40, 41]  Need for surgical intervention includes severe displacement, severe or persistent pain, nonunion, respiratory failure, or dependency on mechanical ventilation and restricted movement of the trunk.[19]

 

 

 

Complications may arise from associated injuries. During evaluation of these patients, carefully assess for cardiac, pulmonary, mediastinal, and thoracic spine injuries, as well as associated injuries unrelated to chest trauma.[8]

Chest pain after injury can persist for 8 to 12 weeks. Pain on inspiration can result in atelectasis, pneumonia, and other pulmonary complications.[14]

The elderly may experience prolonged recovery because of pain and osteoporotic bone. These patients should join a physical therapy program to regain their strength and muscle mass.[14]

Cardiac contusion is much less common than once thought; its incidence ranges from 6 to 18%, based on severity of trauma.

Traumatic aortic injury occurs in fewer than 2% of sternal fractures, a rate similar to that in patients with blunt chest trauma without sternal fracture.

Nonunion of sternal fractures is very rare. Painful pseudoarthroses occur when a false joint develops secondary to failed union of a fracture and may require delayed surgical repair. Similarly, overlap deformities may require delayed surgical repair.

A posttraumatic mediastinal abscess is very uncommon. Risk factors include the presence of a large hematoma, intravenous drug abuse, and another source of a staphylococcal infection. Treatment is open debridement.

Primary treatment is adequate analgesia with nonsteroidal anti-inflammatory drugs and opiates. Select these on the basis of relative indications and contraindications for each patient and administer in standard doses and routes. Since sternal fractures can take weeks to heal, do not hesitate to offer adequate analgesia for this recovery period. No other pharmacologic therapies are indicated specifically for treatment of sternal fractures.

Class Summary

These agents are most commonly used for relief of mild to moderately severe pain. Effects of NSAIDs in the treatment of pain tend to be patient specific, yet ibuprofen is usually the drug of choice for initial therapy. Other options include fenoprofen, flurbiprofen, ketoprofen, and naproxen.

Ibuprofen (Ibuprin, Advil, Motrin)

Usually DOC for treatment of mild to moderately severe pain if no contraindications. Inhibits inflammatory reactions and pain, probably by decreasing activity of enzyme cyclooxygenase, which inhibits prostaglandin synthesis.

Ketoprofen (Oruvail, Orudis, Actron)

Used for relief of mild to moderately severe pain and inflammation. Administer small dosages initially to patients with small bodies, older persons, and those with renal or liver disease. Doses higher than 75 mg do not increase therapeutic effects. Administer high doses with caution and closely observe for response.

Naproxen (Anaprox, Naprelan, Naprosyn)

Used for relief of mild to moderately severe pain. Inhibits inflammatory reactions and pain by decreasing activity of enzyme cyclooxygenase, which inhibits prostaglandin synthesis.

Class Summary

Pain control is essential to quality patient care. It ensures patient comfort, promotes pulmonary toilet, and aids physical therapy regimens. Many analgesics have sedating properties that benefit patients who have sustained fractures.

Acetaminophen (Tylenol, Panadol, aspirin-free Anacin)

DOC for treatment of pain in patients with documented hypersensitivity to aspirin or NSAIDs or those with upper GI disease or taking oral anticoagulants.

Acetaminophen and codeine (Tylenol #3)

Drug combination indicated for treatment of mild to moderately severe pain.

Hydrocodone bitartrate and acetaminophen (Vicodin ES)

Drug combination indicated for relief of moderately severe to severe pain.

Oxycodone and acetaminophen (Percocet)

Drug combination indicated for relief of moderately severe to severe pain. DOC for aspirin-hypersensitive patients.

Morphine sulfate (Duramorph, Astramorph, MS Contin)

DOC for narcotic analgesia because of its reliable and predictable effects, safety, and ease of reversibility with naloxone. Administered IV, may be dosed in a number of ways and commonly is titrated until desired effect obtained.

Class Summary

These agents are effective in reducing pain and inflammation.

Aspirin (Anacin, Ascriptin, Bayer aspirin)

Used for treatment of mild to moderately severe pain and headache. Blocks prostaglandin synthetase action, which inhibits prostaglandin synthesis and prevents formation of platelet-aggregating thromboxane A2. Also acts on hypothalamus heat-regulating center to reduce fever.