Thoracolumbar Spine and Lower Extremity Fractures

Thoracolumbar Spine and Lower Extremity Fractures

Ernest L. Sink

John M. Flynn


Clinical Features.

Spine fractures in children represent 1% to 2% of all pediatric fractures (1). Most of these injuries involve the cervical spine and are discussed in Chapter 21. Causes of spine injury include falls, athletic activities, and battering, but trauma due to motor vehicle accidents is most common (2, 3 and 4). Thoracolumbar spine injuries are more common in older children and adolescents but less common than in adults (5). The true incidence is difficult to determine and the reported incidence may be too low because some children with trauma severe enough to cause spinal fracture may die from associated injuries (6). Approximately two-thirds of thoracolumbar spine fractures in adults are in the region of T12-L2, but the distribution of pediatric and adolescent spine fractures is more uniform throughout the thoracic and lumbar spine (7).

There is a 50% incidence of associated injuries in children who sustain spine trauma from motor vehicle crashes (3). Complete examination is essential when evaluating a child with multiple injuries because spine fractures are occasionally overlooked (8, 9). Physical examination has a high sensitivity when diagnosing spine fractures (5). Examination may reveal tenderness, swelling, ecchymosis, or a palpable defect posteriorly along the spinous processes. A seat belt mark across the abdomen or injury of an abdominal organ should increase the index of suspicion. Any loss of sensory or motor function should be accurately documented.

Spinal cord injury is less frequent in children than in adults. Perhaps this is because the pediatric spine is much more flexible than the adult spine, allowing greater deformation without fracture. This increased musculoskeletal elasticity is not shared by the spinal cord and may lead to a clinical entity known as spinal cord injury without radiographic abnormality (SCIWORA) (10). The disproportionately large head size and other structural features in children place the cervical and upper thoracic regions at greatest risk for spinal cord injury. Trauma to the lower thoracic or lumbar spine in children is rarely associated with spinal cord injury. The prognosis for recovery from incomplete neurologic injury is better in children than in adults, but complete lesions rarely improve (3).

Plain radiographs should be obtained when spine trauma is suspected, but these may be difficult to interpret. Multilevel injuries are common so imaging of the entire spine is recommended (2). A computed tomography (CT) scan or an MRI or both are indicated for evaluation of most patients when thoracolumbar injuries are suspected or known to be present (9). A CT scan is especially helpful to evaluate the bony structures. Sagittal and coronal reconstruction can be used to evaluate alignment and spinal canal encroachment. MRI is more useful than CT scan to evaluate the spinal cord, intervertebral discs, and other soft-tissue structures (9). An MRI is indicated in all cases with neurologic deficit.

Anatomy and Classification.

The thoracic and lum bar vertebrae develop form three main ossification centers, one each for the left and right sides of the neural arch and one for the body. The junction of the arches with the body occurs at the neurocentral synchondrosis. This junction is visible radiographically until the age of 3 to 6 years. It lies just anterior to the base of the pedicle and can be misinterpreted as a congenital anomaly or a fracture in younger children. Secondary centers of ossification occur in flattened, disc-shaped epiphyses superior and inferior to each vertebral body. These centers provide longitudinal growth but do not cover the entire vertebral
body (11). Ossification of these growth plates at the age of 7 to 8 years creates the radiographic impression of a groove at the corner of each vertebral body. This groove is circumferential around the upper and lower end plates of each vertebra. The ligaments and discs attach to this groove, which is therefore an apophyseal ring. The ring apophysis develops its own ossification center by the age of 12 to 15 years and fuses with the remainder of the vertebra at skeletal maturity (12).

Classification systems for thoracolumbar spine fractures in children have not been proposed. The three-column theory of Denis (13) allows classification of adult fractures and also has relevance for the pediatric population. According to this theory, the thoracolumbar spine consists of anterior, middle, and posterior columns. The anterior column includes the anterior longitudinal ligament, the anterior half of the vertebral body, and the anterior portion of the annular ligament. Middle column structures are the posterior half of the vertebral body, the posterior annulus, and the posterior longitudinal ligament. The posterior column includes the neural arch, the ligamentum flavum, the facet joint capsules, and the interspinous ligament. Spinal stability is primarily dependent on the status of the middle column (14).

Denis (13) applied this three-column theory to classify minor or major thoracolumbar fractures. Minor injuries include isolated fractures of the posterior elements. Major fractures are subdivided into compression fractures, burst fractures, seatbelt-type injuries, and fracture dislocations. Compression of the anterior column is usually stable and results from axial loading in flexion. Lateral compression fractures of the vertebral body may also occur. Further compression results in a burst fracture that is unstable because the middle column becomes involved. Lap-belt injuries (Chance fractures) are unstable because they disrupt the posterior and middle columns by flexion and distraction forces. Fracture dislocations usually involve all three columns and result from various combinations of forces.

Certain types of thoracolumbar injuries are unique to children; these include most cases of SCIWORA, posterior limbus or apophyseal fractures, and fractures associated with child abuse.

Compression Fractures.

Most compression fractures in children occur in the thoracic spine. Underlying causes of bone fragility, such as leukemia, should be considered when trauma has been minimal. Multiple compression injuries are not uncommon. Remodeling with restoration of anterior vertebral height has been observed in children younger than 13 years (4, 7). When wedging of a thoracic or lumbar vertebra is <10 degrees, symptomatic treatment is recommended until the patient is comfortable, followed by gradual resumption of activities. When wedging is >10 degrees and the Risser sign is <3, immobilization in hyperextension is recommended for a period of 2 to 3 months (4). Surgical stabilization is recommended when compression is >15 degrees, or approximately 50% compression of the anterior vertebra, compared to posterior vertebral height. Surgical stabilization is also recommended when lateral compression is >15 degrees (6, 15). The authors follow these guidelines, although prolonged bracing after initial treatment is usually avoided.

Burst Fractures.

Treatment guidelines for burst fractures are similar to those for compression fractures in children and adolescents. These injuries may be managed nonoperatively when the posterior column is intact, deformity is minimal, and there is no neurologic injury (4, 16, 17 and 18). However, progressive kyphosis has been noted in some patients treated nonoperatively (18). Nonsurgical treatment usually consists of hyperextension casting for 2 to 3 months and bracing for an additional 6 to 12 months. Surgical decompression and instrumentation are recommended for patients with greater degrees of deformity or with neurologic compromise (16, 17). Posterior distraction and instrumentation may achieve decompression by ligamentotaxis with reduction of the retropulsed fragments (19). Anterior decompression has been recommended in the presence of multiple nerve root paralysis, but the role of anterior decompression and instrumentation remains controversial (20).

Lap-belt Fractures (Chance-type Fracture).

This flexion distraction injury has been associated with the use of lapbelt restraints, when the lap belt slides up the torso and rests over the abdomen instead of the proximal thighs and hips (20). The incidence of Chance fractures in children has increased since the introduction of mandatory seat-belt laws. Fortunately, this injury has a better prognosis in children than in adults (21). Neurologic deficits are infrequent, but intra-abdominal injury is common and obscures the diagnosis of spine trauma.

A flexion distraction injury is unstable in most patients. Treatment consists of cast immobilization for 8 to 10 weeks when there is minimal displacement and the fracture line goes through bone. Posterior surgical stabilization is indicated in the presence of displacement, neurologic deficits, or when there is a significant ligamentous disruption. Instrumentation and fusion one level above and one level below the fracture may be required. In some patients one-level posterior fusion is sufficient (8, 20), typically with pedicle screw fixation in older children (Fig. 34-1).

Limbus Fracture (Apophyseal Fracture).

This fracture is typically seen in the adolescent or young adult and presents clinically like a herniated nucleus pulposus. It often results from the patient’s lifting a heavy object, but may result from falls or twisting injuries. The patient may describe a “pop” at the time of injury, followed by radiculopathy. Delayed diagnosis is common (22). Takata et al. (23) described four types of growth-plate injuries to the spine. Nonoperative management is rarely successful regardless of the type (17, 22). MRI, CT scan, or both should be used to determine the exact location and configuration of the lesion. Surgical excision is then performed by piecemeal excision of the limbus fragment. In order to completely remove bony impingement, the authors recommend laminectomy with direct exposure rather than relying on minimally invasive techniques.

FIGURE 34-1. A: Anteroposterior and lateral lumber spine radiographs of an 8-year-old with a lap-belt injury. There is slight distraction of the spinous processes and posterior swelling. There was also an abdominal injury B: MRI with posterior ligamentous increased signal. C: Close observation with extension cast immobilization as the original treatment revealed the unstable ligamentous characteristics of the Chance injury. A two-level posterior fusion was thus performed.


Clinical Features.

Fractures of the pelvis are less common in children than in adults and represent only 0.2% of all pediatric fractures (28). The immature pelvis is more malleable than that of an adult, largely because of the lower modulus of elasticity of pediatric bones, and the greater flexibility of adjacent joints. More energy is required to cause a fracture in the immature pelvis. The greater energy absorption also means that associated injuries are common and the greatest cause of morbidity. Motor vehicle-related accidents are the most common cause of pediatric pelvic fractures (29, 30 and 31). Most unstable pelvic fractures are caused when a motor vehicle strikes a pedestrian (31, 32). Pediatric pelvic fractures include avulsion fractures (usually sports injuries, covered in Chapter 31, stable and unstable pelvic ring fractures, and acetabular and triradiate cartilage injuries. Most pediatric pelvic fractures are stable and minimally displaced.

Approximately 20% of polytraumatized children have pelvic fractures (33), and approximately 58% to 87% of children with pelvic fractures have associated injuries (31, 32). These associated injuries include head injuries, intra-abdominal trauma, urologic disruptions, and fractures. There is little to no difference in mortality rates or injury severity as measured by the ISS between adults and children (34). Death occurs in 3% to 5% of children with juvenile pelvic trauma (28, 31, 32). Death is most frequently related to head injury and mortality related to exsanguination due to the pelvic fracture alone is rare (34). Yet, exsanguination from fractures or visceral injuries can occur, and the risks of hemorrhage and associated visceral injuries correlate with fracture patterns. Patients with bilateral anterior and posterior fractures are at greatest risk, whereas isolated pubic ramus fractures have the lowest risk of hemorrhage and intra-abdominal injury (35, 36).

Evaluation includes a careful physical examination for associated injuries, including neurologic deficits. Any laceration should be inspected to determine whether an open fracture has occurred. Rectal examination is indicated to look for hemorrhage signifying bone penetration into the rectum and to verify intact perineal sensation (i.e., sacral plexus function). Pelvic stability should be tested with anterior and lateral compression of the pelvis. Peripheral arterial circulation should also be noted. A single anteroposterior plain radiograph can provide key information about the pelvic ring and is useful for initial screening. If there are indications of a more unstable injury, these other views should be obtained once the patient is stable: pelvic inlet (40 degrees caudal), outlet (40 degrees cephalad), and Judet (45 degrees oblique) views. These views can help define the fracture pattern and the potential involvement of the acetabulum and triradiate cartilage injury. These views have largely been replaced with CT scan, with or without three-dimensional reconstruction. CT scan, often routinely obtained looking for visceral injury, can diagnose minor fractures in the pelvic ring and assist with classification and decision making when operative intervention is indicated.

Anatomy and Classifications of Pelvic Fractures.

The pelvis is formed from three ossification centers: the ischium, the pubis, and the ilium. These come together at the acetabulum to form the triradiate cartilage. Secondary ossification centers can be confused with fractures. These appear at the apophyses in patients between 13 and 16 years of age. The apophyses that are principally associated with avulsion injuries are located on the ischial tuberosity, the anterior inferior iliac spine, and the anterior iliac crest. Secondary centers of ossification can also develop along the pubis and the ischial spine. Several other normal variants can also be confused with fractures. An area of particular confusion is at the junction of the inferior pubic ramus and the ischium. Before ossification, this junction can have the appearance of a fracture, especially when ossification is asymmetric. A swelling may also occur in this area and can simply be observed when asymptomatic.

Several classifications have been proposed for pelvic fractures (37); however, the key features for decision making include (i) whether the pelvis is mature or immature (38) and (ii) if the fracture is stable or unstable. Mature patients with a closed triradiate are managed according to adult treatment classification and guidelines. Plain radiographs can allow reliable determination of fracture types, although CT scanning may be
helpful in questionable cases or when surgical intervention is anticipated (39). The authors prefer the classification proposed by Watts (40):

  • Avulsions

  • Fractures of the pelvic ring (stable and unstable)

  • Fractures of the acetabulum

Pelvic fracture stability can be subclassified using the AO/ASIF classification of adult pelvic fractures (30). This classification is based on both the mode of injury and the resulting characteristics of the fracture.

Type A: Stable Injury.

Stable injuries include fractures of the pubic ramus (Fig. 34-2) or iliac wing. The ramus fractures may be isolated or may involve both the superior and the inferior rami. It should be noted that, because of the elasticity of the child’s pelvis, diastasis of the pubic symphysis can occur in children without instability of the sacroiliac joint posteriorly. In young children, this fracture usually represents separation at the bone-cartilage junction rather than joint disruption. This “single ring” fracture that is stable without anterior symphysis or ramus injury may also occur near the sacroiliac joint.

Type B: Rotationally Unstable Fractures.

This is a pelvic ring disruption that is stable in the vertical plane but unstable in the transverse plane. Mechanisms include lateral compression causing, for instance, pubic and ischial ramus fractures with contralateral sacral fracture. Alternatively, anterior compression may cause an “open-book” type of injury with pubic diastasis.

Type C: Rotationally and Vertically Unstable Fractures.

This group includes bilateral pubic rami fractures (straddle injuries), which rarely displace in children; vertical shear fractures through the ipsilateral anterior and posterior pelvic rings; and anterior ring fractures with acetabular disruption.


Hip Dislocation.

Traumatic dislocation of the hip in children is uncommon, representing only 5% of all pediatric dislocations. Most hip dislocations are posterior, but anterior and obturator dislocations can occur (46, 47). The mechanism of
injury depends somewhat on the age of the child. Hip dislocations in children younger than 8 years are frequently the result of mild trauma because joint laxity is common and the acetabulum is largely cartilaginous (Fig. 34-5) (47). Dislocations in children older than 8 years are more often the result of moderate or severe trauma. Dislocation from moderate trauma may result in spontaneous, incongruous reduction and capsular interposition (48). This is rare but easily misdiagnosed in children and adolescents. Any suggestion of joint-space widening should be investigated with a CT scan. An MRI may be valuable to visualize any cartilage and labrum that may be an impediment to reduction in the immature nonossified acetabular rim (Fig. 34-6).

FIGURE 34-5. Traumatic hip dislocation in a 3-year-old boy. A: This anteroposterior pelvis radiograph was taken upon presentation of a 3-year-old boy who twisted his leg while running down the stairs. B: This anteroposterior pelvis radiograph was taken immediately after closed reduction in the emergency room. On long-term follow-up, there was no avascular necrosis or any other sequelae.

Hip Fractures.

Hip fractures in children represent <1% of all pediatric fractures (1). In contrast to adult hip fractures, pediatric and adolescent hip fractures are usually the result of high-energy trauma because considerable force is required
to produce a fracture in this age group. The exceptions to this are infants who have been subjected to child abuse, and fracture through a pathologic lesion of the femoral neck (e.g., bone cyst). Complications are frequent and have been reported in 15% to 60% of patients (52, 53). Prompt and appropriate management may reduce the risk of subsequent complications.

FIGURE 34-6. A: Pelvis x-ray of a 7-year-old. There is slight widening of the left hip joint (arrow) with no fracture visualized B: MRI of the hip showing soft tissue (labral/cartilage, arrow) not visible on plain radiographs entrapped in the posterior hip impeding reduction.

Anatomy and Classification.

In the infant, the proximal femur is composed of a single large cartilaginous growth plate (54). The medial portion becomes the epiphyseal center of the femoral head, ossifies at around 4 months of age, and forms the proximal femoral physis. The lateral portion of the proximal femur forms the greater trochanter physis, with ossification of the epiphysis by 4 years of age. Injury to the proximal femur can affect one or both of these centers of growth. The proximal femoral physis is responsible for the metaphyseal growth of the femoral neck and provides approximately 15% of the total length of the femur. The greater trochanter helps shape the proximal femur, and damage to this apophysis in children younger than 8 to 10 years may produce an elongated, valgus femoral neck (55, 56).

The vascular supply of the growing child’s proximal femur is jeopardized by these fractures, and the extent of damage greatly affects the final outcome. The dominant arterial source for the femoral head is the lateral epiphyseal vessels, which are the terminal extension of the medial femoral circumflex artery. These vessels penetrate the capsule at the base of the neck near the piriformis fossa and run along the lateral periosteum giving off several branches to the femoral neck before entering the femoral head just proximal to the epiphyseal cartilage (Fig. 34-7) (57, 58). The lateral circumflex system can supply blood to a portion of the anterior femoral head until 2 to 3 years of age, after which it primarily supplies the metaphysis. In children older than 14 to 18 months, the proximal femoral physeal plate becomes an absolute barrier to the metaphyseal blood supply and prevents direct vascular penetration of the femoral head (57, 58). Thus, the epiphyseal and metaphyseal circulation remain separate until complete physeal closure occurs. The vessels of the ligamentum teres do not contribute a significant portion of the blood supply to the femoral head, especially in children younger than 8 years.

It is postulated that some displaced fractures may leave the vascular leash intact but kinked and occluded until realignment is established (59). This has been demonstrated by arteriography before and after reduction of an unstable slipped capital femoral epiphysis (60). Vascular disruption as a cause of avascular necrosis is supported by the fact that the magnitude of displacement is a prognostic factor for the development of necrosis (61). It has also been suggested that prompt decompression of the intracapsular hematoma contributes to the restoration of normal vascular flow and reduces the incidence of femoral head necrosis (62, 63, 64 and 65).

A study of nondisplaced hip fractures in adults confirmed high intracapsular pressures with decreased blood flow on bone scan. Following aspiration and fixation, repeat bone scans demonstrated restoration of blood flow (66). Other studies have also reported high intracapsular pressures that are reduced by joint decompression (66, 67 and 68). Soto-Hall et al. (69), in 1964, noted that intra-articular pressures increased when intracapsular hip fractures were manipulated by placing the leg in internal rotation and extension. The increased joint pressure during reduction of fractures in this position has been confirmed by other authors (66, 68). Reduction of intracapsular fractures may improve vascularity by restoring normal arterial position. However, fracture reduction may also lead to increased intracapsular pressure unless the hip is decompressed. Prompt anatomic reduction, internal fixation, and decompression are recommended in order to restore circulation in a timely manner. This approach to the management of hip fractures and unstable slipped capital femoral epiphyses in children has been associated with a decreased risk of avascular necrosis (62, 63, 65, 70).

FIGURE 34-7. Arterial supply of the developing proximal femur. A: The anterior view demonstrates the lateral circumflex artery (LCA), which supplies the metaphysis and the greater trochanter. The medial circumflex femoral artery (MCA) is the dominant vessel to the femoral head. B: The superior view shows the lateral ascending artery, which sends numerous epiphyseal and metaphyseal branches (arrows) that supply the greatest volume to the femoral head and neck. These ascending cervical branches traverse the articular capsule as the retinacular arteries. The interval between the greater trochanter and the hip capsule is extremely narrow, and is the area where the lateral ascending cervical artery passes. This may be a site of vascular compression or injury.

FIGURE 34-8. Delbet’s classification for proximal femur fractures. A: Type I is a transepiphyseal fracture. B: Type II is a transcervical fracture. C: Type III is a cervicotrochanteric fracture (basicervical). D: Type IV is an intertrochanteric fracture.

Delbet’s classification (Fig. 34-8) offers a useful system for the treatment and prognosis of proximal femur fractures (71). Type I fractures are transphyseal separations. Physeal separation in infants is occasionally seen as a birth fracture or as a result of intentionally inflicted injury. Obstetric fracture separations have excellent clinical results, without avascular necrosis, although diagnosis and treatment may be delayed (72). Children younger than 2 years with type I fracture also have a good prognosis without surgical management (73). Transepiphyseal separations in older children result from more severe trauma, but separation has been reported during reduction of hip dislocation in the adolescent age group (74). When the epiphyseal fragment is dislocated from the acetabulum, the risk of avascular necrosis approaches 100%. However, the incidence of avascular necrosis is variable when the femoral head remains within the joint (71).

Type II fractures occur in the neck of the femur between the epiphyseal plate and the base of the neck. These injuries constitute approximately 50% of all fractures of the proximal femur (71). Complications are frequent with type II fractures. The incidence of avascular necrosis approaches 50% to 60%, and the nonunion rate is 15%. Premature physeal closure may also occur, but because growth of the proximal femur is approximately 15% of the total limb (75), clinically important leg-length discrepancy is unlikely to occur in older children.

Type III fractures occur in the cervicotrochanteric, or basal neck, region of the femoral neck. This is the second most common type of hip fracture in children. Avascular necrosis occurs in 30% of displaced fractures. Malunion has been reported in 20%, and nonunion occurs in 10%, of these patients. These problems may be lessened by precise fracture reduction, combined with compression across the fracture site by means of cancellous bone screws (i.e., lag technique) (71, 76).

Type IV fractures occur in the intertrochanteric region and are associated with the least risk of damage to the femoral head vascular supply. The incidence of avascular necrosis is between 0% and 10%. Varus deformity is the most likely complication, but this may correct with growth in younger children (71, 76, 77).


Femoral shaft fractures account for 1% to 2% of all fractures in childhood (1, 88). There is a bimodal age distribution, with a peak incidence at 2 to 3 years of age and another peak in adolescence. The cortical thickness of the femur increases rapidly after 5 years of age, and this may explain the decreasing incidence of femur fracture in late childhood. Intentional injury should always be considered in children who are not yet walking, but there are no distinguishing age, clinical parameter, or fracture patterns to help determine which injuries are inflicted and which are accidental (89). In infants younger than 1 year, child abuse has been identified as a cause in 65% of patients when obvious causes such as motor vehicle accidents are eliminated (89). Abuse should be indicated in any child with a femur fracture from 0 to 3 years with the greatest incidence in those younger than 1 year or walking age. Children in the toddler age group may sustain fractures with relatively minor trauma from causes such as falling from a low height or tripping while running. In the 4- to 7-year age group, approximately half of the femoral shaft fractures are caused by bicycle accidents. In the adolescent age group, motor vehicle accidents account for most of the femur fractures.

As stated by Rang (90), “It does not require a physician to diagnose a fractured femur.” However, the physician must carefully examine the patient completely. Children and adolescents with femur fracture have a 35% to 40% incidence of associated injuries. Some of these injuries are occult, such as femoral neck fracture, hip dislocation, ligamentous instability of the knee, and visceral injuries (91, 92). Hemodynamic instability or steadily declining hematocrit does not occur because of an isolated, closed femur fracture. Other sources of blood loss must be sought in these patients (92).

Jul 21, 2016 | Posted by in ORTHOPEDIC | Comments Off on Thoracolumbar Spine and Lower Extremity Fractures
Premium Wordpress Themes by UFO Themes