Chest wall injuries after blunt trauma in children

INTRODUCTION — Chest wall injuries in children are significant primarily because they often occur as the result of forceful mechanisms that cause serious associated injuries. Because the thoracic cage of a child is more elastic and flexible than that of an adult, less of the force of impact is absorbed by the chest wall, and proportionally more force is transmitted to intrathoracic organs. Intrathoracic injury (such as pulmonary contusion) often occurs without visible damage to the chest wall.

This topic will review the epidemiology, injury types, evaluation, and management of chest wall injuries in children. Included in chest wall injuries are rib fractures, flail chest, and sternal and scapular fractures. Thoracic trauma, intrathoracic injuries, and pulmonary contusion in children, as well as thoracic trauma and rib fractures in adults, are discussed separately. (See "Thoracic trauma in children: Initial stabilization and evaluation" and "Overview of intrathoracic injuries in children" and "Pulmonary contusion in children" and "Initial evaluation and management of blunt thoracic trauma in adults" and "Initial evaluation and management of rib fractures".)

EPIDEMIOLOGY — Chest wall injuries in children typically occur as the result of blunt thoracic trauma. Rib fractures constitute the majority of these injuries [1,2]. In a prospective series describing 80 children with thoracic injuries following blunt torso trauma, 28 had rib fractures, and one had a fractured sternum [1]. (See 'Rib fractures' below.)

In reports describing children with thoracic injuries evaluated in pediatric trauma centers, most patients were injured as passengers or pedestrians in motor vehicle crashes [1-3]. Among infants and young children, however, rib fractures occur most commonly as the result of abusive injury. (See "Orthopedic aspects of child abuse", section on 'Rib fractures'.)

Mortality for children with chest wall injuries is usually the result of associated injuries, particularly head injury. In several retrospective series describing children with thoracic trauma, 4 to 14 percent of deaths occurred because of thoracic injuries alone. Mortality rates for children with chest and head injuries ranged from 28 to 37 percent [2,4,5]. The presence and number of rib fractures are positively correlated with mortality. As an example, in one observational study of over 19,000 patients under 21 years of age with rib fractures, mortality increased from 2 percent for no rib fractures to 6 percent for one fracture and 8 percent for seven fractures [6]. The presence of any rib fracture compared with no fracture remained strongly associated with increased mortality even after adjustment for injury severity.

ANATOMY — Anatomic structures that comprise the chest wall include ribs, costal cartilages, sternum, clavicles, and intercostal muscles. Neurovascular bundles (comprised of an intercostal nerve, artery, and vein) run along the inferior margin of each rib and may be damaged when a rib is fractured. The pectoralis muscles contribute to the support of the anterior chest wall, while the scapula provides additional protection to the superior posterior chest. Functionally, the chest wall is an essential part of the mechanics of respiration and provides protection for intrathoracic organs. (See "Initial evaluation and management of blunt thoracic trauma in adults", section on 'Anatomy and Injury Patterns'.)

Anatomic differences in the chest walls of children, as compared with adults, influence mechanisms of injury:

●Increased cartilage content and incomplete ossification of the ribs make the thoracic cage of a child more compliant than that of an adult [7]. Consequently, significant force is usually required to produce chest wall injuries in children. This was illustrated in one observational series describing children admitted to a pediatric trauma center with thoracic trauma in which those with multiple rib fractures were more severely injured than those without rib fractures [8].

●Because the chest wall of a child is more compliant, more kinetic energy can be transmitted to the intrathoracic structures without bony injury. For this reason, pulmonary contusion without rib fracture occurs more often in children than adults. (See "Pulmonary contusion in children", section on 'Pathogenesis'.)

INJURY TYPES

Rib fractures — Rib fracture is the most common chest wall injury among children [1,2]. In observational series from pediatric trauma centers, rib fractures were identified in over 30 percent of children evaluated for blunt thoracic trauma. A rib fracture occurring in isolation is uncommon (6 percent in one study) and should prompt a thorough evaluation for associated injuries [9].

Rib fracture may occur as the result of a direct blow to the rib or from compression of the chest in an anterior-posterior direction [10].

●With a direct blow, the rib may fracture inward and puncture the pleural cavity, causing a pneumothorax. Hemothorax can develop when the fractured rib lacerates an intercostal artery, an internal mammary artery, or the lung parenchyma.

●Compression of the chest wall can cause the lateral portions of the ribs to fracture outward. Intrathoracic injury is seen less commonly with this mechanism.

Rib fractures may be characterized as upper zone (ribs 1 to 4), midzone (ribs 5 to 8), and lower zone (ribs 9 to 12) [11]. The location of the rib fracture determines the likelihood of serious associated injuries:

●First rib fractures – Because the upper ribs (one to four) are protected by the scapula, humerus, and clavicle (along with their muscular attachments), a significant amount of force is required to fracture these ribs. Consequently, sternal and scapular fractures as well as serious injuries such as pulmonary contusion and injury to intrathoracic vessels or cervical spine are associated with fractures of the first and second ribs [11-14]. In one series, 1 in 32 children with first rib fractures had an associated vascular injury, and it was associated with an abnormal mediastinum on plain chest film [15].

●Lower rib fractures – Injury to abdominal organs can occur with lower rib fractures. This was demonstrated in a retrospective review describing adults and children hospitalized with rib fractures in which right and left lower rib fractures were associated with liver and spleen injuries, respectively [16]. (See "Pediatric blunt abdominal trauma: Initial evaluation and stabilization".)

Flail chest — A flail chest occurs when the chest wall loses stability as the result of multiple rib fractures (figure 1). The mechanism usually is direct impact or crush injury. It is an uncommon injury among children as indicated in the following reports:

●In one retrospective study from a large trauma registry describing 262 patients with flail chest, 2 percent were between 0 and 14 years of age [17].

●In two large retrospective series describing chest injuries in children, 1 percent of patients had flail chest [4,18].

A flail segment can occur in different locations:

●Anterior – Fracture of the sternum and multiple costochondral junctions

●Posterior – Midaxillary fracture with fracture or dislocation of rib heads

●Lateral – Row of rib fractures both anteriorly and posteriorly

Patients with flail chest can develop respiratory compromise because the flail segment responds to changes in intrathoracic pressure rather than to the pull of respiratory muscles (retracting with inspiration and bulging with expiration) (figure 1). Ventilatory disturbances develop because of the following:

●Paradoxical movement of the chest wall results in inefficient expansion of the thorax, causing a significant increase in energy expenditure for breathing.

●Pain from fractures causes hypoventilation, resulting in atelectasis.

●Patients with flail chest often have pulmonary contusions that cause shunting and ventilation-perfusion mismatch. (See "Pulmonary contusion in children".)

As with other types of chest wall injury, mortality from flail chest is typically related to associated injuries [17].

Sternoclavicular injury — Posterior dislocation or displaced fracture of the medial clavicle can be associated with injury to intrathoracic structures such as great vessels and the esophagus. Clinical features that have been reported in association with posterior displacement of the medial clavicle include dysphagia, dyspnea, hoarseness, and signs of vascular injury. Sternoclavicular injuries in children and adolescents is discussed in greater detail separately. (See "Traumatic causes of acute shoulder pain and injury in children and adolescents", section on 'Sternoclavicular injury'.)

Sternal fractures — Sternal fractures occur infrequently among children [19]. Although they may be associated with significant mechanisms (such as motor vehicle crashes), observational series have described children with isolated sternal fractures that occurred as the result of direct blows or flexion-compression of the spine without associated intrathoracic injuries [20-22]. Sternal fractures have been reported as the result of inflicted injuries but do not appear to be specific for abusive mechanisms [23].

Sternal fractures may be associated with substernal hematoma, pulmonary contusion, vertebral spine injury, rib fractures, and serious trauma to other body regions [19]. Blunt cardiac injury occurs uncommonly.

Scapular fractures — Scapular fractures are uncommon among children [24]. Anatomic position, chest wall compliance, and surrounding muscle protect the scapula from injury. As a result, significant force is usually required to produce a scapular fracture.

In several retrospective reviews describing adolescent and adult patients with scapular fractures as the result of blunt trauma, those with scapular fractures were more likely than those without scapular fractures to have serious associated injuries including [25-28]:

●Fractures of the ribs, clavicle, spine, skull, and upper extremity

●Intrathoracic injury including pulmonary contusion and pneumothorax

●Head injury and intracranial hemorrhage

Injury to the axillary artery or brachial plexus may also occur in association with a scapular fracture because these structures are close to the ventral surface of the scapula. In one of the reports noted above, brachial plexus injury occurred in 5 percent of patients [26].

In addition, scapular fractures are associated with great vessel injury, although the frequency is still low (approximately 1 percent) [29]. Children with scapular fractures warrant careful multisystem evaluation and treatment based upon findings. (See "Thoracic trauma in children: Initial stabilization and evaluation", section on 'Major trauma'.)

PRIMARY EVALUATION AND MANAGEMENT

Initial stabilization — Among children, chest wall injuries typically occur as the result of forceful mechanisms such as motor vehicle crashes. Consequently, many patients may have life-threatening and/or serious associated injuries that must be quickly identified and stabilized. A primary survey should rapidly identify airway compromise, the possibility of a cervical spine injury, respiratory failure, and/or shock (table 1). (See "Trauma management: Approach to the unstable child", section on 'Primary survey'.)

For those children who do not have obvious multisystem injuries, historical features, physical examination, and plain radiograph of the chest typically identify those with significant chest wall injuries such as flail chest, pulmonary contusion, or rib fracture with abdominal organ injury such as liver or spleen laceration.

History — A detailed description of the mechanism may identify children likely to have significant injuries. A discrepancy between the history and physical or radiographic findings (such as healing rib fractures on the chest radiograph of a child being evaluated for nonspecific respiratory complaints) suggests physical child abuse. (See "Physical child abuse: Recognition".)

Physical examination — Once life-threatening injuries have been identified and stabilized, a complete physical examination should be performed (see "Thoracic trauma in children: Initial stabilization and evaluation", section on 'Evaluation'). Vital signs, including respiratory rate and pulse oximetry, may indicate respiratory compromise. Patients with altered awareness or agitation may be hypoxemic or hypoperfused. Children with asymmetric pulses may have intrathoracic vessel injuries [13].

The following specific features of the examination should be noted:

●Abnormal chest wall movement (as may occur with splinting from pain or with a flail segment)

●Ecchymosis, abrasions, or deformity of the chest wall

●Focal tenderness to palpation over ribs, sternum, or scapula

●Subcutaneous air

●Abnormal breath sounds

●Muffled heart tones or a new murmur

●Abnormal upper-extremity pulses or sensation

Muscle splinting or the use of positive-pressure ventilation may conceal the paradoxical motion of a flail segment, delaying diagnosis of a flail chest.

Ancillary studies — Initial laboratory studies and diagnostic imaging for the seriously injured children are discussed separately. (See "Trauma management: Approach to the unstable child", section on 'Adjuncts to the primary survey'.)

Patients with chest pain, tenderness, chest wall bruising, abnormal heart sounds, or abnormal upper or lower extremity pulses require an electrocardiogram (ECG), as do those with a sternal fracture. (See "Initial evaluation and management of blunt cardiac injury", section on 'Pediatric considerations'.)

In addition to these studies, all patients with findings of chest wall injury should have chest imaging for injuries suggested by history, physical examination, and the initial anterior-posterior (AP) chest radiograph. Diagnosis of specific chest wall injuries may require additional views. (See 'Diagnosis' below.)

Computed tomography angiography (CTA) of the chest is primarily indicated for children with signs of aortic injuries or chest wall injuries commonly associated with great vessel injury (eg, sternal fracture or posterior sternoclavicular fracture or dislocation). Although more sensitive for other intrathoracic injuries, it does not change management in most children. (See "Thoracic trauma in children: Initial stabilization and evaluation", section on 'Major trauma'.)

DIAGNOSIS — Chest wall fractures are suspected based upon physical examination findings (bruising, abrasions, focal tenderness, chest wall deformity, or abnormal chest wall movement) and, in most children, are confirmed on plain radiograph of the chest. Additional imaging may be indicated in selected patients:

●Rib fractures – When physical child abuse is suspected, the addition of oblique plain radiographic views may improve identification of rib fractures although rib views are not routinely recommended [30]. Rib fractures in children under two years of age are highly suggestive of child abuse. In patients with clinical findings suggestive of rib fracture, ultrasonography can also detect fractures that may not appear on plain radiographs. (See "Physical child abuse: Diagnostic evaluation and management" and "Orthopedic aspects of child abuse", section on 'Rib fractures'.)

Children with lower rib fractures often warrant abdominal computed tomography (CT) with intravenous (IV) contrast to exclude laceration to the liver (right lower rib fractures) or spleen (left lower rib fractures).

●Scapular fractures – Trans-scapular or Y plain radiographs improve identification of scapula fractures.

●Posterior sternoclavicular fractures or dislocations – Posterior sternoclavicular fracture or dislocations are often not apparent on plain radiographs and require CT to confirm the diagnosis and identify associated intrathoracic injuries. (See "Traumatic causes of acute shoulder pain and injury in children and adolescents", section on 'Diagnosis'.)

●First rib or sternal fractures – Symptomatic children with first rib or sternal fractures should be evaluated for associated injuries to the great vessels similar to the approach in adults and according to their clinical condition and findings on plain radiographs (algorithm 1). (See "Thoracic trauma in children: Initial stabilization and evaluation", section on 'Thoracic imaging'.)

MANAGEMENT

Initial — Initial management of children with chest wall injuries should be directed toward stabilizing life-threatening intrathoracic and other associated injuries (table 1). (See "Thoracic trauma in children: Initial stabilization and evaluation" and "Trauma management: Approach to the unstable child".)

Specific considerations for children with chest wall injuries include:

●Patients with rib fractures who require tube thoracostomy to relieve pneumo- or hemothorax should have tubes placed at sites separate from the areas of fracture. (See "Thoracostomy tubes and catheters: Indications and tube selection in adults and children".)

●Children with flail chest should receive respiratory support. Those with respiratory distress or failure should be intubated and receive positive-pressure ventilation to provide adequate oxygenation and ventilation as well as to optimally expand and splint the injured segments.

●Children younger than three years of age with rib fractures and without a history of high-force trauma warrant evaluation for child abuse in consultation with a child abuse specialist and multidisciplinary child abuse team. Mandatory reporting of a suspicion of abuse is required for physicians and other medical providers in many regions. Clinicians must know and abide by mandatory reporting statutes in the jurisdictions where they practice. (See "Physical child abuse: Diagnostic evaluation and management" and "Child abuse: Social and medicolegal issues", section on 'Reporting suspected abuse'.)

Definitive — Definitive management of specific injuries is determined by a pediatric surgeon with thoracic trauma expertise according to the type of injury:

●Multiple rib fractures – Patients with multiple acute rib fractures typically warrant admission to a pediatric trauma center for:

•Pain control to improve respiratory function; achievement of pain control often requires involvement of a specialized pediatric pain team.

•Age-appropriate pulmonary physiotherapy to prevent atelectasis.

Splinting rib fractures with external devices can worsen ventilatory compromise and should be avoided.

●Flail chest – Because of the plasticity of the pediatric rib cage, flail chest occurs rarely in children. Treatment consists of:

•Pain management and, in most patients, mechanical ventilation; for patients with flail chest who do not require respiratory support, aggressive pulmonary physiotherapy and pain control.

•Careful fluid management for those with underlying pulmonary contusion. (See "Pulmonary contusion in children", section on 'Management'.)

•Surgical fixation may be helpful for rare patients who develop significant long-term respiratory dysfunction or persistent instability of the injured segment [31,32].

●Isolated sternal fractures – Children with isolated sternal fractures who have normal electrocardiograms (ECGs) and chest imaging and are comfortable can be managed as outpatients [22]. Those who require more aggressive pain control or have associated injuries require hospital admission.

●Scapular fractures – Most children with scapular fractures have serious associated injuries that require hospital admission. Because of the numerous muscle attachments supporting the scapula, nondisplaced or minimally displaced scapular fractures can be treated nonsurgically with a sling [29]. Displaced fractures of the scapular neck and displaced glenoid fractures may require open reduction [33].

OUTCOMES — The prognosis for patients with chest wall injuries is usually related to the severity of associated injuries [6,9,19,28]. Prognosis for isolated sternal fractures is excellent, with most healing within six weeks [19].

Outcomes of specific scapula fractures are discussed separately. (See "Traumatic causes of acute shoulder pain and injury in children and adolescents", section on 'Scapula fractures'.)

SUMMARY AND RECOMMENDATIONS

●Epidemiology – Chest wall injuries include rib fractures, flail chest, and fractures of the sternum or scapula. Rib fractures are the most common pediatric chest wall injury. Chest wall fractures in children often occur after high-force blunt thoracic trauma such as a motor vehicle crash or physical child abuse. Mortality is usually the result of associated injuries, particularly head injury. (See 'Epidemiology' above and 'Injury types' above.)

●Anatomy – The thoracic cage of a child is more compliant than that of an adult. Consequently, pediatric chest wall injuries require considerable force and are more likely to be associated with intrathoracic injury. (See 'Anatomy' above.)

●Initial stabilization – A primary survey should rapidly identify airway compromise, the possibility of a cervical spine injury, respiratory failure, and/or shock. The initial management of chest wall injuries must focus on identifying and stabilizing life-threatening associated injuries (eg, pneumo- or hemothorax and blunt aortic injury) (table 1). (See "Trauma management: Approach to the unstable child", section on 'Primary survey'.)

●Evaluation – Chest wall injuries become fully characterized during the secondary survey:

•History and physical examination – Key findings on physical examination include:

-Abnormal chest wall movement (as may occur with splinting from pain or with a flail segment (figure 1))

-Ecchymosis, abrasions, or deformity of the chest wall

-Focal tenderness to palpation over ribs, sternum, or scapula

-Subcutaneous air

-Abnormal breath sounds

-Muffled heart tones or a new murmur (suggesting hemopericardium or blunt cardiac trauma)

-Abnormal upper-extremity pulses or sensation (suggesting blunt aortic trauma)

•Ancillary studies – Initial laboratory studies and diagnostic imaging for the seriously injured child are discussed separately (see "Trauma management: Approach to the unstable child", section on 'Adjuncts to the primary survey'). Additional studies in children with chest wall injuries are designed to identify fractures and injury to underlying structures and consist of (see 'Ancillary studies' above):

-Electrocardiogram (ECG) and cardiac monitoring in patients with signs of blunt cardiac injury or sternal fracture.

-Emergency echocardiography for children with ECG or clinical findings suggestive of blunt cardiac injury.

-Specific radiographic views based upon suspected fracture (eg, oblique views for rib fractures (image 1) or trans-scapular or Y view for scapular fractures).

-Computed tomography angiography (CTA) in patients with suspected posterior sternoclavicular fractures or dislocations.

-For children with suspicion for aortic injuries, the diagnostic approach is provided in the algorithm and discussed separately (algorithm 1). (See "Overview of intrathoracic injuries in children", section on 'Traumatic aortic injury'.)

●Diagnosis – Chest wall fractures are suspected based upon physical examination findings (bruising, abrasions, focal tenderness, chest wall deformity, or abnormal chest wall movement) and, in most children, are confirmed on plain radiograph of the chest. Additional imaging may be indicated (see 'Diagnosis' above):

•Children with posterior sternoclavicular dislocations on plain radiograph require CTA of the chest.

•Children with first rib fractures and sternal fractures may require CTA of the chest, especially if chest radiograph suggests widening of the mediastinum or hemothorax.

•Children with lower rib fractures often warrant abdominal computed tomography (CT) with intravenous (IV) contrast to exclude laceration to the liver (right lower rib fractures) or spleen (left lower rib fractures).

●Initial management – During stabilization of children with rib fractures and a pneumo- or hemothorax, avoid chest tube thoracostomy near the fracture ribs. Children with flail chests who are in respiratory distress require assisted ventilation, typically endotracheal intubation and mechanical ventilation. (See 'Initial' above.)

Children younger than three years of age with rib fractures and without a history of high-force trauma require evaluation for possible child abuse in consultation with a multidisciplinary child abuse team. Mandatory reporting of a suspicion of abuse is required for physicians and other medical providers in many regions. Clinicians must know and abide by mandatory reporting statutes in the jurisdictions where they practice. (See "Physical child abuse: Diagnostic evaluation and management" and "Child abuse: Social and medicolegal issues", section on 'Reporting suspected abuse'.)

●Definitive management – Definitive management of specific injuries is determined by a pediatric surgeon with thoracic trauma expertise according to the type of injury. Hospital admission is often required because of critical associated injuries to the head, neck, and intrathoracic structures. (See 'Definitive' above.)