Traumatic Injuries of the Cervical Spine
Cervical spine injuries are rare in children and often are difficult to diagnose because of an inability to obtain a clear history and the difficulty of imaging an immature spine. Therefore a high index of suspicion is necessary to avoid missing the diagnosis and incurring associated sequelae. Neurologic injury may be present, despite negative imaging studies. The patterns of injury in children older than 10 years are similar to those in adults, with a greater incidence of subaxial injuries than in younger children, in whom injuries more frequently occur between the occiput and C2. Most injuries do not result in neurologic injury, and nonoperative treatment usually is effective.
Anatomy
Three ossification centers are present in the immature atlas, one for the anterior ring, which usually appears by 1 year of age, and one each for the posterior neural arches. The connection between the anterior and posterior arches is composed of the neurocentral synchondroses, which fuse at 7 years of age and can be mistaken for fracture before this period. The posterior arch usually closes by the age of 3 years but can remain open or partially closed ( Fig. 32-1 ).
The ossification centers of the axis include one for the body, one for each neural arch, and one for the dens ( Fig. 32-2 ). Fusion of the dens to the neural arches and the anterior body occurs between 3 and 6 years of age. During fetal development, the dens is formed from two ossification centers, which fuse during the seventh month of gestation. An ossification center at the tip of the odontoid appears between 4 and 6 years of age and fuses to the remaining odontoid by the age of 12 years. The lower cervical vertebrae follow a similar pattern of development; the ossification centers at the body and each neural arch close by the third year, and the neurocentral synchondroses fuse between the fourth and sixth years.
The blood supply to the odontoid is derived from the anterior and posterior ascending arteries, which branch from the vertebral arteries at the level of the third cervical vertebra and coalesce in the midline. Anastomoses between the carotid and ascending arteries occur near the apex of the odontoid process.
Epidemiology
Although cervical spine fractures in children account for a small percentage of all cervical spine fractures, cervical spine injuries account for most spine injuries in children, with up to 48% of all spine fractures in children occurring in the cervical spine.
In contrast to what is seen in adults, most cervical spine injuries in young children occur between the occiput and C2 because of increased ligamentous laxity and hypermobility, together with a relatively larger head size, which results in the fulcrum of injury being above C3. *
* References .
Atlas and axis injuries accounted for 16% of cervical spine injuries in a large series of adults, as compared with 70% in children. As the child gets older and takes on a more adult body habitus, the incidence of cervical spine injuries is more similar to the adult pattern.The mechanism of injury depends on the age of the child. Obstetric cervical spine injury can occur, particularly in infants with hyperextension of the head in the breech presentation. Cesarean delivery may prevent this catastrophic complication. Infants with cervical spine injury are most commonly the victims of nonaccidental trauma, usually violent shaking. Careful clinical evaluation is important in this age group because a significant number of these injuries may have normal plain radiographs, or spinal cord injury without radiographic abnormality (SCIWORA; see later, “ Spinal Cord Injury Without Radiographic Abnormality ”). †
† References .
In older children, cervical spine injuries are more often caused by motor vehicle accidents (MVAs), pedestrian–motor vehicle encounters, falls from heights, trampoline injuries, all-terrain vehicle accidents, and athletic injuries. ‡‡ References .
Diagnosis
Every child evaluated after a traumatic event should be questioned about the mechanism of injury and assessed for injury to the cervical spine. Risk factors for cervical spine injury include facial abrasions or lacerations, head trauma, clavicle fractures, high-speed MVAs, and falls from a height. Painful torticollis may be present in an alert child with a cervical spine injury.
Physical examination should include a head to toe assessment by the entire trauma team. The head and face should be carefully inspected for lacerations and abrasions. The neck should be palpated to elicit tenderness, muscle guarding, or the presence of a gap in the spinous processes, which would indicate a posterior ligamentous injury. A complete orthopaedic assessment of all four extremities and of the remainder of the spine and pelvis should be performed. A thorough neurologic examination must be performed and should include a rectal examination when a neurologic injury is suspected. The importance of a thorough and careful examination cannot be overstated inasmuch as additional orthopaedic injuries have been reported to occur in up to 40% of children with cervical spine injuries, and closed head injuries have been reported in 58% of cases.
A child who arrives in the emergency department unconscious is always considered to have a cervical spine injury. The child should wear a cervical collar to stabilize the cervical spine until the patient is awake and can cooperate with the physical examination. Although there are various protocols for clearance of the cervical spine, plain radiographs and computed tomography (CT) have a high sensitivity and specificity. Magnetic resonance imaging (MRI) may provide more soft tissue information with a higher false-positive rate. A cervical spine injury should be strongly suspected when clonus is present in the extremities without decerebrate rigidity. Surgeons should remember the importance of distracting injuries, particularly other fractures. With especially severe trauma, usually from an MVA, cervical arterial injury may occur, 11% in one series, and CT angiography or MR angiography should be considered.
Radiographic Findings
A radiographic evaluation should be performed when a cervical spine injury is suspected. The two best predictors of cervical spine injury have been described as involvement in an MVA and complaints of neck pain. However, we usually obtain radiographs in any patient with cervical tenderness, distracting injuries, altered mental status, alcohol or drug intoxication, or a neurologic deficit.
Cervical Spine Radiographs
Although plain radiographic assessment of the child may be difficult, up to 98% of injuries can be diagnosed on lateral cervical spine radiographs, so careful assessment of good-quality radiographs is the critical first step in the evaluation of children with cervical spine injury. In an unstable patient, a screening lateral radiograph of the cervical spine obtained in the emergency department should be viewed as an initial screening test, and additional views should be obtained when the condition of the patient allows ( Fig. 32-3 ). A complete radiographic examination should include anteroposterior (AP), lateral, open-mouth, and oblique views. When injury is suspected despite normal-appearing radiographs, flexion-extension lateral radiographs should be obtained to help identify pathology ( Fig. 32-4 ). When one injury is identified, it is important to obtain and carefully examine radiographs of the entire spine because multiple sites of injury may be present. The reported frequency of injury to other spinal segments in children with cervical spine (C-spine) injuries ranges from 4% to 35%.
The lateral radiograph should be examined systematically, with the examiner looking first for alignment:
- 1.
Alignment is checked by following the anterior and posterior lines of the vertebral bodies or the spinolaminar line described by Swischuk and Rowe ( Fig. 32-5 ). This line is more important diagnostically than the line connecting the anterior and posterior lines of the vertebral bodies, which may exhibit a step-off, especially at the C2-4 levels.
FIGURE 32-5
Lateral radiograph demonstrating the spinal laminar line of Swischuk. This line is drawn by connecting the anterior edge of the spinous processes of C1, C2, and C3.
- 2.
The posterior interspinous process distance should be assessed. Posterior ligamentous instability is manifested on the lateral radiograph by an increase in the interspinous distance, loss of parallelism between the articular processes, and posterior widening of the disk space ( Fig. 32-6 ).
FIGURE 32-6
Posterior ligamentous instability. A lateral radiograph of a 2-year-old child demonstrates widening of the posterior elements between C1 and C2 ( arrow ), indicating a posterior ligamentous injury.
- 3.
The prevertebral soft tissue width should be measured. Normally, it is less than 5 to 6 mm anterior to the body of C2.
- 4.
Cervical lordosis should be examined. Although loss of cervical lordosis does not denote the presence of cervical spine injury, it may indicate muscle guarding and spasm.
- 5.
Because children have a higher incidence of injuries between the occiput and C3, it is important to evaluate this area carefully and obtain a good open-mouth view.
Accepted criteria for instability of the upper cervical spine in children include more than 10 degrees of forward flexion of C1 on C2 and an atlanto-dens interval (ADI) greater than 4 mm. The upper limit of the ADI in children has been suggested to be 3 ± 0.7 mm in flexion, with less than 0.5 mm of difference in ADI between flexion and extension radiographs. In adults, the transverse ligament is considered ruptured when the ADI is between 3 and 5 mm, and the transverse and alar ligaments are ruptured when the ADI is 10 to 12 mm. In the lower cervical spine no accepted criteria have been developed for children; however, in adults, the accepted amount of angulation between the affected vertebra and adjacent segment is 11 degrees.
Pseudosubluxation refers to forward translation of the anterior aspect of the vertebral body relative to the inferior level, despite normal alignment of the posterior spinolaminar line (Swischuk line, see Fig. 32-5 ). This well-described radiographic variant is a result of normal physiologic development of the cervical spine. In the upper cervical spine of young patients, the facet joints are more horizontal. With growth, the facets become more vertical. Forward displacement of up to 4 mm at C2-3 is normal in children and is usually seen in those younger than 8 years ( Fig. 32-7 ).
Other Studies
Further imaging studies, including CT or MRI, are indicated when abnormalities are seen on the initial plain radiographs and when a cervical spine injury is suspected despite normal radiographs. CT is best used for children suspected of having osseous fractures, facet dislocations, or vertebral end-plate fractures. When fractures extend into the transverse foramina, and with severe subluxations, noninvasive angiography should be considered to discover vascular injuries. MRI is best used to evaluate soft tissue injuries, including posterior ligamentous injury, a herniated disk, encroachment of the neuroforamina, spinal cord lesions and edema, and a posttraumatic spinal cord cyst. MRI may have some prognostic value in distinguishing patients with spinal cord edema, who generally recover neurologically, from patients with intraspinal hemorrhage, who often do not recover. MRI may also be useful for demonstrating injuries to the spinal cord that are remote from the bony injury.
A number of studies have assessed the role of CT and MRI scans to clear the cervical spine in adults and children with altered mental status or a distracting injury. Both these modalities have been shown to be highly sensitive and specific in identifying occult injury. These screening protocols have been shown to decrease the length of hospital stay and may be more effective than dynamic radiographs. Although many protocols have been proposed, there is no universally accepted standard to date. §
§ References
Frank and co-workers reported the results of a protocol to use MRI for clearing the cervical spine in obtunded and intubated pediatric trauma patients who could not be cleared within 72 hours. They reported decreased time to clearance of the cervical spine and decreased length of stay and believed that the MRI protocol was effective and cost-efficient.Treatment
Because a child’s head is proportionally larger than the body, positioning the patient to prevent acute flexion of the neck is important during transport and evaluation. Adult proportions begin to emerge in children at 8 years of age. Because anterior angulation or translation on lateral radiographs have been identified in young children with unstable C-spine injuries when positioned on a traditional backboard ( Fig. 32-8, A ), a bed or backboard with a posterior recess to allow posterior positioning of the head is recommended to prevent flexion of the cervical spine (see Fig. 32-8, B ). Initially, the child should be examined with a cervical collar in place. Although a rigid collar provides some stability to the neck, residual motion can occur. This motion can be limited with the use of tape and sandbags. These devices should be gently removed while a second examiner applies a stabilizing force with mild in-line traction as the posterior elements are palpated. The hard collar is then replaced and appropriate imaging studies performed. When ventilatory support is required, the best method of intubation is controversial. It appears that gentle in-line traction with orotracheal or nasotracheal intubation is safe and does not lead to further neurologic injury. Pharmacologic treatment of patients with neurologic injuries is discussed later (“Pharmacologic Treatment of Spinal Cord Injury”).
Atlantooccipital Dislocation
This relatively rare injury usually occurs in MVAs and is associated with high mortality ( Fig. 32-9 ). Although atlantooccipital dislocation often is fatal, some children will survive this injury. There are numerous case reports of other children who have survived traumatic atlantooccipital dislocation but most survivors have neurologic complications. ‖
‖ References .
Radiographic assessment of atlantooccipital dislocation can be difficult because radiographs obtained in the emergency department may appear normal. These injuries may be suspected from subtle plain film findings, such as an increased interspinous process distance. Although a number of radiographic measurements have been described, we prefer to use the Powers ratio when evaluating this injury ( Fig. 32-10 ). Historically, when atlantooccipital injury was strongly suspected in the absence of good radiographic evidence, the diagnosis was made with a lateral radiograph taken with mild traction carefully applied to the head. However, MRI has increasingly been used to identify this injury and other, more subtle injuries to the tectorial membrane.
Treatment consists of halo application and stabilization and posterior fusion from the occiput to C1 or C2. ¶
¶ References .
Postoperatively, the patient is immobilized in a halo vest or halo cast ( Fig. 32-11 ). Although internal fixation in a young child is difficult, we have placed sutures or metal wire around the posterior elements of C1 and C2 and through the base of the skull. In older children fixation with bicortical occipital screws and facet screws with contoured rods may provide stable fixation. Dural leak and venous sinus injury have been reported. Hedequist and co-workers reported a 100% fusion rate when pediatric fractures were treated with modern C-spine instrumentation systems often used for adults. Following instrumentation, halo immobilization is often required, especially in active children. The duration of immobilization should be 3 to 4 months. Patients with more stable injuries, such as tectorial membrane abnormalities noted on MRI scans, can be managed with immobilization without fusion.
Atlas Fractures
Fracture of the ring of C1, the so-called Jefferson fracture, is caused by an axial compressive force applied to the head that results in direct compression of the ring of C1 by the occipital condyles. This very rare injury accounts for less than 5% of all cervical spine fractures in children. The fracture may be at multiple sites within the ring of the atlas or it may be at the neurocentral synchondrosis. Jefferson fractures may be seen on plain radiographs, but usually can be detected by displacement of the lateral masses. CT scans will identify the atlas fracture more completely if significant displacement occurs. The transverse ligament may become stretched and incompetent and result in C1-2 instability, which should be evaluated with lateral flexion-extension radiographs.
Atlas fractures should be treated by external immobilization for 3 to 4 months. We prefer immobilization with a halo vest or halo cast, although a Minerva cast or noninvasive halo has been used. When C1-2 is unstable, treatment requires fusion and stabilization of this joint, as outlined in the following discussion of traumatic atlantoaxial instability.
Traumatic Atlantoaxial Instability
In adults, instability of the atlantoaxial junction is usually a result of injury to the transverse ligament and alar ligaments, and it results in an increased ADI. In the pediatric population, traumatic atlantoaxial instability occurs most commonly in older children ( Fig. 32-12 ). In a younger child, traumatic instability may result from injury to the synchondrosis at the base of the dens. Nontraumatic atlantoaxial instability also is seen in younger children with underlying conditions such as Down syndrome, Morquio syndrome or other skeletal dysplasias, and juvenile rheumatoid arthritis.
The rule of thirds, first described by Steel, is helpful in assessing atlantoaxial instability. The distance between the anterior and posterior arches of C1 is divided into three equal areas ( Fig. 32-13 ). The anterior third is filled with the odontoid, followed by the spinal cord, and finally an unoccupied area, which provides a cushion for the spinal cord.
The diagnosis of traumatic atlantoaxial instability is made with plain radiographs. The ADI should initially be assessed on true lateral radiographs of the cervical spine taken in neutral position. If injury is suspected, the ADI also should be assessed on flexion-extension views. There are no absolute radiographic parameters to guide treatment of traumatic atlantoaxial instability in children. However, we perform surgical stabilization when anterior translation is more than 8 to 10 mm or neurologic deficits are present.
In adults, when the odontoid is displaced posteriorly for a distance equal to its diameter, the spinal cord is endangered, and surgical stabilization of C1-2 is recommended to prevent neurologic injury. Surgical treatment includes the application of a halo ring to facilitate positioning of the head and neck, with C1 and C2 in a reduced position, followed by posterior spinal fusion between C1 and C2. Internal fixation in a young child is often difficult; however, a Gallie or Brooks fusion provides additional stability to the C1-2 segment ( Fig. 32-14 ). Halo immobilization should be maintained for approximately 2 to 4 months, depending on radiographic healing and the age of the child. In an older child (>11 years), more stable fixation using transarticular screws between C1 and C2 may require less external immobilization. Some have used only a soft cervical collar for 8 weeks after transarticular fixation. We use 3.5-mm cortical screws placed under direct observation to obtain solid purchase in the anterior cortex of the anterior ring of the atlas. This technique can be supplemented with a Gallie or Brooks fusion ( Fig. 32-15 ). If evaluation is delayed from the time of injury, it may be necessary to use halo traction to reduce the anterior translation before surgical stabilization is undertaken.
Odontoid Fractures
Odontoid fractures account for approximately 10% of all cervical spine fractures and dislocations in children; however, only approximately 10% of all odontoid fractures occur in children. #
# References .
In a child the injury occurs at the synchondrosis at the base of the dens. The mechanism of injury usually is relatively severe, with falls from a significant height and MVAs accounting for most injuries. However, in children younger than 4 years, the mechanism of injury may be minor, such as a fall from a bed or a fence or a fall from a crib. Consideration should be given to possible associated injuries, most commonly facial fractures, but pulmonary and visceral injuries have been described.Traditionally, neurologic injury has been considered rare; however, this probably occurs more frequently than appreciated. Odent and colleagues reported neurologic injuries in 8 of 15 children, all of whom had complete lesions at the level of the cervicothoracic junction. These injuries often are missed because of the innocuous nature of the original injury and the absence of impressive signs and symptoms. The patient may complain of neck pain, and there may be tenderness on palpation over the upper cervical spine. Persistent pain and neck irritability should alert the physician to injury. A clinical sign reported to correlate well with an odontoid fracture is resistance to the examiner’s attempts to extend the neck. The child also will resist attempts to be brought to an erect or recumbent position unless the head is supported by the examiner.
The dens usually is displaced anteriorly, often more than 50% of its width on a lateral radiograph. In approximately 10% to 15% of patients, the displacement is posterior or there is no displacement. In such cases the injury is difficult to see on plain radiographs, and further imaging studies, such as CT with sagittal images or tomography, may be necessary. In patients with neurologic injury, MRI may demonstrate spinal cord injury (SCI) distal to C2, which is thought to be caused by significant anterior displacement of the upper spine, leading to stretch of the spinal cord over the cervicothoracic junction.
Children with odontoid fractures generally can be treated successfully by nonoperative means. * a
References .
We prefer closed reduction with the patient sedated to allow constant neurologic assessment. We usually immobilize the patient in a halo vest or cast for 2 to 3 months until solid union is achieved. Before complete removal of the halo, flexion-extension radiographs should be obtained to identify any motion at the fracture site. Nonunion is extremely rare when this fracture is identified and treated early. Nonunion requires operative intervention with anterior screw fixation or posterior fusion of C1-2. The latter is preferred in a small child, whereas the former may be a reasonable option for an adolescent.Os odontoideum is a C-spine anomaly in which the dens is separated from the body of the axis. The dens becomes an ossis, with smooth cortical margins ( Fig. 32-16 ). The cause of os odontoideum has been debated. Some have hypothesized that it is essentially a nonunion from unrecognized remote trauma. Others believe that it represents a congenital anomaly. Os odontoideum may be an asymptomatic normal variant or may produce neck pain or neurologic symptoms. Symptomatic patients should be treated by posterior C1-2 fusion.
Traumatic Spondylolisthesis of C2 (Hangman’s Fracture)
Traumatic spondylolisthesis of C2 is rare in children, with few cases reported in the literature. †a
†a References .
The mechanism of injury is generally extension and axial loading, with a high incidence of injuries to the face and head. The injury usually is incurred in MVAs or a fall from a height. It also has been reported in infants as a result of nonaccidental trauma. Injury in this age group may be difficult to distinguish from a congenital abnormality. Neurologic injury is rare in these injuries, although some have reported neurologic deficits that appeared to resolve over the following year. We usually obtain a CT scan in all suspected cases of hangman’s fracture to define the extent of the fracture and amount of displacement fully ( Fig. 32-17 ).
In a reliable patient an undisplaced fracture, or a fracture with less than 3 mm of anterior displacement of C2 on C3, can be treated by external immobilization in a hard collar. However, we have a low threshold for using a halo vest. When there is more than 3 mm of displacement, gentle reduction should be performed and the patient immobilized in a halo vest for 2 to 3 months.
Fractures and Dislocations of the Subaxial Spine
Fractures and dislocations of the subaxial spine are relatively rare in young children; however, the incidence in children older than 8 years is similar to that in adults. When all cervical spine injuries are included (including C1-2 rotatory subluxation and SCIWORA), subaxial injuries account for only 23% of injuries. These injuries can be subdivided into fracture-dislocations, burst fractures, compression fractures, posterior ligamentous injuries, unilateral or bilateral facet dislocations, and bilateral facet fractures. Fracture-dislocation has been reported to be the most common subaxial injury ( Fig. 32-18 ). This injury is usually the result of an MVA or a fall with a direct blow to the head. The diagnostic workup should include MRI followed by a reduction maneuver and stabilization of the spine.
A burst fracture is caused by axially applied loads to the head, generally with the head slightly flexed. The characteristic fracture pattern includes anterior displacement of the anteroinferior aspect of the body, a teardrop fracture. The danger occurs with the posterior aspect of the vertebral body, which fractures in the sagittal plane and can travel posteriorly into the canal. These injuries are usually associated with neurologic injury and frequently are the injury sustained by football players. Birney and Hanley reported six children with a burst fracture; two had a transient incomplete neurologic injury, and one had a permanent complete injury. Both CT and MRI are helpful for defining the anatomy of the canal, posterior ligamentous structures, and intervertebral disk. In a patient with a neurologic injury, gentle closed reduction with a halo should be performed, followed by immobilization in a halo cast for 2 to 3 months. If neurologic injury is present and persists despite fracture reduction with in-line traction, anterior decompression with removal of the retropulsed fragments should be performed, followed by strut grafting. The anterior approach should be used with caution in very young children because continued posterior growth with a solid anterior fusion may produce excess kyphosis. When a burst fracture is associated with significant posterior ligamentous instability, posterior fusion may decrease the likelihood of postoperative deformity.
Compression fractures are caused by a pure flexion moment without significant rotatory or axial loading. This leaves the posterior ligamentous structures intact and does not injure the posterior aspect of the vertebral body; therefore it does not result in protrusion of bone or disk into the spinal canal. These injuries are relatively rare in children and usually do not result in neurologic injury. Neurologic injury is rare with this injury because of the lack of posterior body injury and thus less risk of retropulsion into the canal.
Compression fractures often are difficult to diagnose because of the mild radiographic findings and the normal, anteriorly wedged shape of the vertebral body in children. Treatment consists of cervical spine immobilization in a cervical collar for 2 to 4 months, depending on the age of the child and extent of injury. Surgical treatment is reserved for patients with unacceptable kyphosis, which may not remodel.
Posterior ligamentous injuries result from flexion and flexion-rotation mechanisms, with tearing of the posterior ligaments and the facet joint capsule. When the flexion-rotation force is relatively mild, a posterior ligamentous injury occurs. With higher energy injury, unilateral or bilateral perched or dislocated facets may occur. In children, the cartilaginous portion of the facet may produce the appearance of a perched facet when there is actually complete dislocation. Pure ligamentous injury is rare in children and is not generally associated with neurologic injury.
Treatment is based on the degree of instability, which has not been fully defined in children. In adults, instability can be defined as the angulation between adjacent vertebrae in the sagittal plane of 11 degrees more than the adjacent normal segment or translation in the sagittal plane of 3.5 mm or more. Because most of these injuries occur in patients older than 10 years, similar criteria can be used in children. Significant posterior ligamentous injury requires posterior fusion with an autologous bone graft and internal fixation with spinous process wires. Minor ligamentous injuries may be managed conservatively, particularly in a very young (<3-year-old) child. With a unilateral facet dislocation, there is anterior translation between the vertebral bodies of 25% to 50% of the sagittal diameter, which may result in unilateral nerve root or spinal cord compression. Bilateral facet dislocations are very unstable injuries, with a high risk of causing neurologic injury. Unilateral or bilateral facet dislocation is treated by acute reduction with halo traction and conscious sedation. Reduction is achieved by skeletal traction. Serial lateral radiographs should be obtained after each incremental increase in traction to determine whether reduction has occurred. The head should be in a slightly flexed position and then extended as radiographs demonstrate that the facets are aligned and almost reduced. After closed reduction of a unilateral facet dislocation, most children can be successfully treated with 2 to 3 months of immobilization in a halo cast. Bilateral facet dislocations are usually treated with a posterior arthrodesis, although closed treatment can be successful in a child younger than 3 years. Failure to reduce a unilateral or bilateral facet dislocation requires open reduction and fusion with posterior wiring and halo immobilization for 2 to 4 months.
Traumatic Injuries of the Thoracic and Lumbar Spine
Injuries of the thoracic and lumbar spine are less common in children than are C-spine injuries. Patients in the first decade of life are more likely to sustain upper thoracic (T4 to T10) injuries and are more likely to be injured from falls or motor vehicle–pedestrian collisions. They may also be injured by abuse. ‡a
‡a References .
Patients in the second decade of life are more likely to sustain injuries at the thoracolumbar junction and are commonly injured in MVAs or during recreational events. §a§a References .
Neurologic injury occurs in approximately 50% of patients with thoracic or lumbar fractures, with a slight predominance of incomplete lesions. These high-energy injuries frequently are associated with other visceral or orthopaedic injuries, including multiple injuries of the spinal column. ‖a‖a References .
The nomenclature for thoracic and lumbar spine fractures is somewhat confusing because thoracic and lumbar injuries, as well as injuries at the thoracolumbar junction, are frequently referred to as thoracolumbar injuries. We reserve the term thoracolumbar injuries for injuries occurring between T12 and L1.Anatomy
An understanding of the anatomy of the immature spine is important in evaluating and treating children with spinal injuries. The pediatric spine is more flexible than the adult spine, which may contribute to the frequency of neurologic injury and the finding of SCIWORA. Several factors contribute to the flexibility of a child’s spine. First, the soft tissues are more forgiving, the ligaments are more elastic, the muscles are smaller, and the intervertebral disks are healthy and well hydrated. Second, there is a higher ratio of cartilage to bone. Finally, the facets are more horizontal, thereby allowing greater motion. Vertebral growth occurs equally from the superior and inferior apophyses, which develop within the cartilaginous end-plate. These apophyses are wider peripherally than centrally, which gives them a ring appearance, the origin of the term ring apophysis. They are similar to the epiphysis of a long bone. Ring apophyses appear radiographically between 8 and 12 years of age and fuse with the vertebral body between 21 and 25 years of age.
Management of children with thoracic and lumbar spinal injuries requires an understanding of the three-column spine, a concept introduced by Denis in 1983. This anatomic description provides the basis for the most efficient means of classification and a foundation for a rational approach to treatment. Denis determined that complete rupture of the posterior ligamentous structures did not produce instability. Rather, instability in flexion required not only rupture of the posterior ligaments but also disruption of what he termed the middle column —the posterior longitudinal ligament, posterior annulus fibrosus, and posterior wall of the vertebral body ( Fig. 32-19 ). The anterior column consists of the anterior longitudinal ligament, anterior annulus fibrosus, and anterior vertebral body. The posterior arch and posterior ligamentous complex (the supraspinous and interspinous ligaments, facet joint capsules, and ligamentum flavum) make up the posterior column.
Mechanism of Injury
Thoracic and lumbar spine injuries are usually the result of high-energy forces. Motor vehicle–related injuries are the most common, although falls, recreational activities, all-terrain vehicle (ATV) accidents, child abuse, obstetric injury, and gunshots have all been reported as mechanisms of injury. ¶a
¶a References
The force that produces the injury is usually flexion, which may be combined with compression, distraction, or shear forces. #a#a References .
With ATV injuries, younger children had more lumbar fractures whereas those older than 16 years had thoracic spine fractures more often. Extension injuries have been described but are extremely uncommon.The events leading to spinal fracture can be outlined as follows. As a vertical load is applied, the end-plate bulges toward the vertebral body; there is little change in the annulus or nucleus of the disk. As the load increases, deformation of the end-plate forces blood out of the cancellous bone of the vertebral body, thereby decreasing its energy-absorbing ability. Eventually, the elastic limit of the vertebral body is exceeded and fracture occurs. The elasticity of the pediatric spine allows these forces to be distributed over multiple levels, which explains why multiple compression fractures are seen more commonly in children. If a distraction or shear force exists concurrently, it may also produce deformity, usually through the end-plate rather than the disk.
Neurologic injury is classified as primary or secondary. Primary injuries are the result of direct injury to the neural elements and may be caused by contusion, stretch, compression, or laceration. Contusion injuries are most common and have a poor prognosis for recovery. Compression produces injury primarily through direct neuronal damage and secondarily by altering vascular perfusion. Secondary injuries are the result of ischemia and are most common in the watershed area of the thoracic spine (T7 to T10). Ischemic injury is a mechanical and biochemical cycle. The initial injury produces a mechanical ischemia, which results in cell death and the release of vasoactive substances. These substances produce vasoconstriction and edema. The edema leads to further mechanical compression, and the cycle continues. Because of their cyclic nature, ischemic injuries may evolve over time, and a delayed manifestation of neurologic injury is not uncommon. Ischemic SCIs may be exacerbated by systemic hypotension associated with shock from other traumatic injuries. Paraplegia has been reported in children and adults with hypotensive episodes and no injury to the spinal cord.
Classification
We use Denis’ five-part classification of spinal column injuries ( Box 32-1 ). Spinal injuries are classified as minor or major and then subdivided into four classes. Minor injuries include fractures of the spinous and transverse processes, facets, and pars interarticularis. Major injuries include compression fractures, burst fractures, seat belt injuries, and fracture-dislocations. Compression fractures represent failure of only the anterior column. There is no loss of posterior vertebral body height. The intact middle column is pathognomonic for compression fractures. Burst fractures result from failure of the anterior and middle columns in flexion; the posterior column remains intact. A lateral radiograph will reveal fracture of the posterior wall, loss of posterior vertebral body height, and tilting of one or both end-plates. Retropulsion of fragments into the canal may be difficult to appreciate on the lateral radiograph and is best seen on CT scans. The AP radiograph will show loss of vertebral body height and a widened interpedicular distance. Seat belt injuries are the result of a flexion-distraction force. Both the posterior and middle columns fail in tension; the anterior column may remain intact or may fail in compression. Seat belt injuries are further subdivided according to the location (through bone or ligament) of the posterior and middle column injury and whether both columns are injured at the same level or at adjacent levels ( Fig. 32-20 ). Although distraction injuries are more common with lap belt restraint, they may occur in children properly wearing three-point restraints. Fracture-dislocations are the last and most unstable class of thoracic and lumbar injuries. These injuries represent failure of all three columns in compression, tension, rotation, or shear.
Diagnosis
Thoracic and lumbar spine injuries may be difficult to diagnose. These patients frequently have multiple injuries and an altered state of consciousness. Occasionally the elasticity of the pediatric spine allows it to recoil into a more normal position. If this occurs, the displacement at the time of injury, and subsequently the amount of instability, may not be appreciated on initial radiographs ( Fig. 32-21 ). Thus all patients with significant traumatic injuries should be assumed to have spinal column instability until such an injury is excluded. All trauma patients should be log-rolled during the initial assessment, and the entire spine should be inspected and palpated for ecchymosis, soft tissue swelling, step-offs, and tenderness. Obviously, the patient’s inability to move the extremities heightens the suspicion of spinal column injury, as should significant abdominal injuries and the seat belt sign—a large ecchymosis over the abdomen.
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