Chapter 25: Pelvic and Acetabular Fractures

James McCarthy, Martin J. Herman, Wudbhav N. Sankar

Chapter Outline

Introduction to Pelvic and Acetabular Fractures

Pelvic and acetabular fractures in children vary from simple apophyseal avulsion and stress fractures to high-energy unstable pelvic ring injuries that are life-threatening. Pelvic and acetabular fractures in the pediatric population are quite uncommon. Pelvic fractures account for less than 1% of all pediatric fractures, but as many as 5% of children admitted to level 1 pediatric trauma centers with blunt trauma have pelvic fractures.4,10,11,14,25,99 Although published studies focus on pelvic fractures from high-energy mechanisms, most pelvic fractures in children and adolescents occur from low-energy mechanisms and are stable ring injuries or avulsions of secondary ossification centers of the pelvis. Acetabular fractures, especially as isolated pelvic fractures, are rare in the pediatric age group. 
Pediatric pelvic and acetabular fractures differ in important ways from adult pelvic fractures. Children in general have greater plasticity of the pelvic bones, increased elasticity of the sacroiliac joints and symphysis pubis, and thicker and stronger periosteum. Therefore, a relatively greater amount of energy can be dissipated before sustaining a pelvic fracture in a child as compared to an adult, and the relative force needed to sustain a pelvic fracture in a child is higher than in an adult.13,31,83,95 The presence of the triradiate cartilage is another major difference. This critical physeal area is responsible for acetabular growth and development, acts as a stress riser in the pelvic ring, and is susceptible to permanent damage. These important differences correlate with clinical outcomes. Children have a lower mortality rate associated with these injuries compared to adults and, when mortality occurs, it is more commonly related to associated injuries of the thorax, abdomen, and central nervous systems rather than direct blood loss from the pelvic injury.4,11,14,25,30,36,51,69,83,94,99 
Most low-energy stable pelvic ring injuries and avulsions are treated through conservative measures. Unstable pelvic ring injuries may be a source of life-threatening hemorrhage in children. Coordinated management of a multidisciplinary trauma team and careful treatment of the associated head and thoracoabdominal injuries, in addition to pelvic ring fracture management, improve outcomes. Although historically most pelvic fractures, including unstable injuries, were treated nonoperatively, experience extrapolated from the care of adults with pelvic fractures has led to a growing movement to treat selected cases surgically in an attempt to decrease long-term disability.19,41,96 In addition, follow-up after acetabular fractures in children with at least 2 years of growth remaining is critical because damage to the triradiate cartilage may cause a long-term growth abnormality.41 

Assessment of Pelvic and Acetabular Fractures

Mechanisms of Injury for Pelvic and Acetabular Fractures

Most pediatric pelvic fractures result from motor-vehicle related accidents.4,11,52,69,83 These injuries are seen most commonly in children who are occupants of motor vehicles involved in collisions or who are struck by motor vehicles while riding a bicycle or other types of wheeled vehicles.80 Other mechanisms include falls from motorized vehicles, such as all-terrain vehicles or motor bikes, falls from heights, and equestrian accidents. 
Sporting activities account for 4% to 11% of pelvic fractures, the majority of which are simple avulsion fractures of the secondary ossification centers of the growing pelvis. Avulsion injuries are the result of forceful contraction of large muscles, typically those which traverse both the hip and knee joints and have their origins on pelvic apophyses. Gymnasts typically sustain acute ischial tuberosity avulsion fractures from the violent pull of hamstring muscles, whereas soccer players more commonly sustain avulsions of the anterior-superior and anterior-inferior iliac apophyses, the result of contraction of the sartorius and rectus femoris muscles, respectively.70 Iliac apophysitis is most frequently associated with long distance running and is thought to result from repetitive muscle traction injury from the pull of the external oblique muscles of the abdomen.12 
Much like pelvic ring fractures, acetabular fractures usually result from high-energy injuries, although sporadic cases of low-energy mechanisms from sports have been reported.19,51 The mechanism of injury of acetabular fractures in children is similar to that in adults: the fracture occurs from a force transmitted through the femoral head to the articular surface of the acetabulum. The position of the leg with respect to the pelvis and the direction of the impact determine the fracture pattern; the magnitude of the force determines the severity of the fracture or fracture-dislocation. For example, forces applied along the axis of the femur with the hip in a flexed position usually result in injury to the posterior aspect of the acetabulum. Fractures of the acetabulum are intimately associated with pelvic fractures. Some acetabular fractures involve only the hip socket. Others represent the exit point of a fracture of the pelvic ring. Pelvic fractures, particularly ramus fractures, may propagate into the triradiate cartilage (Fig. 25-1). Even fracture-dislocations of the sacroiliac joint have been associated with triradiate cartilage injuries.43,76 
Figure 25-1
 
A: Pelvic radiograph showing a pelvic fracture with the left superior rami injury propagating toward the triradiate cartilage. B: CT scan showing the rami fractures propagating into the triradiate cartilage.
A: Pelvic radiograph showing a pelvic fracture with the left superior rami injury propagating toward the triradiate cartilage. B: CT scan showing the rami fractures propagating into the triradiate cartilage.
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Figure 25-1
A: Pelvic radiograph showing a pelvic fracture with the left superior rami injury propagating toward the triradiate cartilage. B: CT scan showing the rami fractures propagating into the triradiate cartilage.
A: Pelvic radiograph showing a pelvic fracture with the left superior rami injury propagating toward the triradiate cartilage. B: CT scan showing the rami fractures propagating into the triradiate cartilage.
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Child abuse is a rare cause of pelvic and acetabular fractures. The diagnosis of a pelvic fracture in infants and very young children, especially those without a reported history of high-energy injury, mandates a thorough investigation by the child protection team and child welfare services. 

Associated Injuries with Pelvic and Acetabular Fractures

While death rates in children who sustain pelvic fractures have been reported to be as high as 25%, most series report a mortality rate of 2% to 12% in children.1,5,1214 Significant hemorrhage that requires blood transfusion occurs in as many as 30% of patients with pelvic fractures80 and is most common in patients who sustain anterior and posterior pelvic ring fractures and those with unstable fractures. However, hemorrhage from pelvic fracture–related vascular injury is the cause of death in less than 1% of children as compared to 3.4% of adults who sustain pelvic ring and acetabular fractures.29,36 One possible explanation for the low rate of hemorrhage relates to the lack of underlying atherosclerotic disease and the increased contractility of children's smaller arterial vessels, both of which result in greater vasoconstriction after injury.36 In addition, children are injured typically in motor vehicle versus pedestrian accidents and therefore tend to sustain lateral compression forces, as opposed to anterior–posterior forces like adults. Injuries caused by laterally directed forces do not as commonly result in expansion of the pelvic ring or disruption of the sacroiliac joints, generally resulting in less intrapelvic hemorrhage.30 
Associated injuries, rather than fractures about the pelvis, are more commonly the causes of morbidity and mortality in children and adolescents who are diagnosed with pelvic ring and acetabular fractures. Between 58% and 87% of children who sustain pelvic fractures have at least one associated injury and many have several.11,20,25,30,69,83 The most common associated injuries are other fractures, particularly of the lower extremities and spine, which are identified in nearly half of children with pelvic fractures.25,80 In one study of 79 children with pelvic fractures, patients with even one additional fracture demonstrated a significantly increased need for other nonorthopedic procedures.97 The incidence of associated traumatic brain injuries varies from as little as 9% to nearly 50%4,11,25,30,52,55,69,83 and clearly is the most important comorbidity that influences outcomes. Associated thoracoabdominal injuries occur at a rate between 14% and 33% in children with pelvic fractures.4,11,14,25,55,80,83 These injuries are second only to head injuries as the primary cause of death in children with pelvic fractures and should be carefully ruled out in children who sustain serious pelvic ring or acetabular injuries. 
Other less common injuries have been reported in children who sustain pelvic fractures. Vaginal and rectal lacerations are seen in 2% to 18% of children with pelvic fractures.3,67,89 The incidence of these injuries is much higher in open fractures of the pelvis, a rare injury in children.54 The surgeon must have a high index of suspicion for these types of injuries because early detection, appropriate irrigation and debridement, and repair of lacerations may prevent the development of infection. Genitourinary injuries, most commonly urethral tears and bladder disruptions, are diagnosed in 4% of patients who sustain fractures25 but hematuria has been noted in up to 50% of children with pelvic fractures.11,66,89 Peripheral nerve injury occurs in less than of 3% of children. Posterior displacement of the hemipelvis or the iliac wing from severe pelvic ring disruption can cause tension on the lumbosacral plexus and sciatic nerve as they exit the pelvis.20,67,92 A thorough neurologic examination of the lower extremities, including motor and sensory testing, and assessment of sphincter tone and perianal sensation should be routine in all patients with displaced fractures. Magnetic resonance imaging (MRI) is sometimes helpful to assess the integrity of the lumbosacral plexus. Neurophysiologic studies are indicated in the recovery phase if deficits persist. 

Signs and Symptoms of Pelvic and Acetabular Fractures

A full systematic examination of the child with a pelvic or acetabular injury is indicated. The patient will often be first seen in the trauma bay by a multidisciplinary trauma team. Other life-threatening issues may prevent a complete examination immediately, and the patient's mental status may be impaired. Secondary examinations after the patient is stabilized are critical to identify lesser injuries that may not have been as obvious initially. 
Evaluation of a child with a suspected pelvic injury should begin with the assessment of the airway, breathing and circulatory status, as with any polytraumatized patient.95 Careful examination of the head, neck, and spine should be performed to assess for spinal injury and closed head injury. A complete neurovascular examination including peripheral pulses should be part of the initial survey. Documentation of the function of the muscles innervated by the lumbosacral plexus and the skin supplied by its sensory branches is sometimes difficult to fully assess in the acute setting. A secondary survey after stabilization of cardiovascular status and provisional treatment of injuries should include this neurologic evaluation in cooperative patients. 
After the primary survey, the evaluation specific to pelvic injuries begins with a complete inspection of the pelvis and perineum to evaluate for lacerations and ecchymosis. The child should be gently log-rolled to facilitate a complete inspection. The Morel-Lavellee lesion (a degloving injury in which the skin and subcutaneous fat is sheared from the underlying muscle, creating a large space where a hematoma can form) may be identified95 (Fig. 25-2). A careful genitourinary evaluation must be performed because of the intimate relationship between the pelvis, bladder, and urethra. Rectal examination has historically been recommended for children with significantly displaced fractures pelvic or if there is any blood in the perineal area. A more recent study, however, revealed that routine use of this examination for all patients may not be necessary, but should be reserved for patients at higher risk for more significant injury.78 
Figure 25-2
Clinical photograph of a Morel–Lavellee lesion, the result of an underlying unstable pelvic fracture.
 
This is an internal degloving injury in which the skin and subcutaneous fat are sheared off the underlying muscle.
 
(Reproduced by permission from Samir Mehta, MD.)
This is an internal degloving injury in which the skin and subcutaneous fat are sheared off the underlying muscle.
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Figure 25-2
Clinical photograph of a Morel–Lavellee lesion, the result of an underlying unstable pelvic fracture.
This is an internal degloving injury in which the skin and subcutaneous fat are sheared off the underlying muscle.
(Reproduced by permission from Samir Mehta, MD.)
This is an internal degloving injury in which the skin and subcutaneous fat are sheared off the underlying muscle.
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Pelvic landmarks including the anterior-superior iliac spine, crest of the ilium, sacroiliac joints, and symphysis pubis should be palpated. Manual manipulation should be performed carefully when needed. The maneuvers are often painful and if performed too vigorously may further displace the fracture or stimulate further intrapelvic bleeding. Pushing posteriorly on the anterior-superior iliac crest produces pain at the fracture site as the pelvic ring is opened. Compressing the pelvic ring by squeezing the right and left iliac wings together also causes pain, and crepitation may be felt if a pelvic fracture is present. Pressure downward on the symphysis pubis and posteriorly on the sacroiliac joints causes pain and possibly motion if there is a disruption. Pain with range of motion of the extremities, especially the hip joint, may indicate articular involvement and other fractures or tendon and ligament injuries. 
Avulsion fractures of the pelvis typically result in localized swelling and tenderness at the site of the avulsion fracture. Motion is limited because of guarding, and pain may be mild or marked. In the case of repetitive stress injury, pain and limitation of motion usually are gradually progressive. In patients with ischial avulsions, pain at the ischial tuberosity can be elicited by flexing the hip and extending the knee (straight-leg raising). In this position, as the hip is moved into abduction, the pain increases. Patients may also have pain while sitting or moving on the involved tuberosity. 

Imaging and Other Diagnostic Studies for Pelvic and Acetabular Fractures

Following initial stabilization of the child, all multitrauma patients and those with suspected pelvic or acetabular trauma should undergo an anteroposterior (AP) radiograph of the pelvis as part of the initial trauma series. Multiple fractures are often an indication of associated thoracoabdominal or head injuries. Once the primary survey is completed and the patient is stable, region-specific radiographs should be obtained of any area with signs of trauma on secondary assessment. 
Additional views, including the inlet and outlet and Judet views are useful for further evaluation of pelvic ring injuries. The inlet view is obtained by directing the x-ray beam caudally at an angle of 60 degrees to the x-ray plate. The inlet view is best for the determination of posterior displacement of a hemipelvis. The outlet view is obtained by directing the x-ray beam in a cephalad direction at an angle of 45 degrees to the x-ray plate. The outlet view best demonstrates superior displacement of the hemipelvis or vertical shifting of the anterior pelvis.91 Internal and external rotation views (Judet or oblique) are primarily obtained when an acetabular fracture is identified. 
A number of studies have tried to identify clinical criteria which would effectively rule out the need for any pelvic radiographs in childhood trauma patients.32,43,45 In general, children with no lower extremity fractures, a normal examination of the abdomen and pelvis, and who are alert and neurologically intact without pelvic pain regardless of a high-risk mechanism of injury, are unlikely to have sustained a pelvic fracture. The value of these criteria for avoiding radiation to the pelvis is a noble effort but its efficacy has not yet been established and most polytraumatized children do not meet these criteria. 
Computer tomography (CT) scanning is considered to be the best modality to evaluate the bony pelvis, especially at the sacroiliac joint, sacrum, and acetabulum. Most authors agree that CT scanning is indicated if there is doubt about the diagnosis on the plain radiographs or if operative intervention is planned. This imaging modality helps better define the type of fracture, the degree of displacement, and can detect retained intra-articular fragments which can prevent concentric reduction (Fig. 25-3).7,9,27,51,82 This information is crucial for determining the best treatment option and selection of the operative approach.48 Three-dimensional CT reconstructions can give an excellent view of the overall bony fracture pattern but often underestimate the magnitude of cartilaginous fragments, especially of posterior wall fractures in children.71 Many trauma centers routinely obtain CT scans of the abdomen and pelvis looking for visceral injury. 
Figure 25-3
 
A: Postreduction anteroposterior pelvis radiograph of a 12-year old with the left hip appearing nonconcentric. B: CT scan showing a bony fragment from the posterior wall impeding reduction.
A: Postreduction anteroposterior pelvis radiograph of a 12-year old with the left hip appearing nonconcentric. B: CT scan showing a bony fragment from the posterior wall impeding reduction.
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Figure 25-3
A: Postreduction anteroposterior pelvis radiograph of a 12-year old with the left hip appearing nonconcentric. B: CT scan showing a bony fragment from the posterior wall impeding reduction.
A: Postreduction anteroposterior pelvis radiograph of a 12-year old with the left hip appearing nonconcentric. B: CT scan showing a bony fragment from the posterior wall impeding reduction.
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MRI currently has minimal role in evaluation of the acute trauma patient, although this practice may evolve with quicker sequencing and better access. MRI is better than CT in delineating soft tissue injuries, and does not emit ionizing radiation. Cartilaginous structures, such as posterior wall fractures associated with hip dislocations, or nonacute fractures, such as occult stress fractures or avulsion fractures, may be diagnosed more readily with MRI.30,71 An MRI is recommended as an adjunctive imaging study for all pediatric acetabular fractures because MRI discloses the true size of largely cartilaginous posterior wall fragments in children (Fig. 25-4). Radioisotope bone scan is rarely indicated but may be useful for the identification of occult pelvic fractures or other acute injuries in children and adults with head injuries or multiple-system injuries.34,91 
Figure 25-4
 
A: Postreduction radiograph of a left hip dislocation in a 12-year-old boy. B: CT scan demonstrates small ossified posterior wall fragments. C: Sagittal MRI demonstrates 90% posterior wall involvement with intra-articular step-off (black arrow).
 
(From Rubel IF, Kloen P, Potter HG, et al. MRI assessment of the posterior acetabular wall fracture in traumatic dislocation of the hip in children. Pediatr Radiol. 2002; 32(6):435–439, with permission.)
A: Postreduction radiograph of a left hip dislocation in a 12-year-old boy. B: CT scan demonstrates small ossified posterior wall fragments. C: Sagittal MRI demonstrates 90% posterior wall involvement with intra-articular step-off (black arrow).
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Figure 25-4
A: Postreduction radiograph of a left hip dislocation in a 12-year-old boy. B: CT scan demonstrates small ossified posterior wall fragments. C: Sagittal MRI demonstrates 90% posterior wall involvement with intra-articular step-off (black arrow).
(From Rubel IF, Kloen P, Potter HG, et al. MRI assessment of the posterior acetabular wall fracture in traumatic dislocation of the hip in children. Pediatr Radiol. 2002; 32(6):435–439, with permission.)
A: Postreduction radiograph of a left hip dislocation in a 12-year-old boy. B: CT scan demonstrates small ossified posterior wall fragments. C: Sagittal MRI demonstrates 90% posterior wall involvement with intra-articular step-off (black arrow).
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In children with avulsions of the pelvis, radiographs will usually show displacement of the affected apophysis. Avulsion injuries affect secondary centers of ossification before the center is fused with the pelvis, primarily in children of ages 11 to 17 years.18,53,88 Comparison views of the contralateral apophysis should be obtained to ensure that what appears to be an avulsion fracture is not in reality a normal adolescent variant. Radiographs of children with delayed presentations of these injuries may demonstrate callus formation and these findings can occasionally mimic a malignant process. 

Classification of Pelvic and Acetabular Fractures

Pelvic Fracture Classification

The Torode and Zieg94 classification based on plain radiographs, and its most recent modification based on radiographs and CT scans,51 is the most commonly used classification of pediatric pelvic fractures. To create this classification, the authors reviewed 141 children with pelvic fractures and classified the injuries on the basis of the severity of the fractures as well as their associated prognosis. The classification has type I (avulsion fractures), type II (iliac wing fractures), type III (simple ring fractures), and type IV (ring disruptions). The modified scheme is identical to the earlier scheme but additionally divides type III “stable” simple ring injuries into IIIA (anterior only ring fractures) and IIIB (anterior and posterior ring fractures) (Table 25-1 and Fig. 25-5).51 The morbidity, mortality, and complications are all greatest in the type IV group with “unstable” ring disruptions. This classification does not include acetabular fractures. 
Table 25-1
Modified Torode and Zieg Classification of Pelvic Fractures in Children
  1.  
    Avulsion fractures
  2.  
    Iliac wing fractures
    1.  
      Separation of the iliac apophysis
    2.  
      Fracture of the bony iliac wing
  3.  
    Simple anterior ring fractures
  4.  
    Stable anterior and posterior ring fractures
  5.  
    Unstable ring disruptions
    1.  
      “Straddle” fractures, characterized by bilateral inferior and superior pubic rami fractures.
    2.  
      Fractures involving the anterior pubic rami or pubic symphysis and the posterior elements (e.g., sacroiliac joint, sacral ala).
    3.  
      Fractures that create an unstable segment between the anterior ring of the pelvis and the acetabulum.
X
Figure 25-5
The modified Torode and Zieg classification.
 
Torode I (avulsion fractures): avulsion of the bony elements of the pelvis, invariably a separation through or adjacent to the cartilaginous growth plate. Torode II (iliac wing fractures): Resulting from a direct lateral force against the pelvis, causing a disruption of the iliac apophysis or an infolding fracture of the wing of the ilium. Torode III-A (simple anterior ring fractures): This group involved only children with stable anterior fractures involving the pubic rami or pubic symphysis. Torode III-B (stable anterior and posterior ring fractures): This new group involved children with both anterior and posterior ring fractures that were stable. Torode IV (unstable ring disruption fractures): This group of children had unstable pelvic fractures, including ring disruptions, hip dislocations, and combined pelvic and acetabular fractures.
 
(From Shore BJ, Palmer CS, Bevin C, et al. Pediatric pelvic fracture: A modification of a preexisting classification. J Pediatr Orthop. 2012; 32(2):162–168.)
Torode I (avulsion fractures): avulsion of the bony elements of the pelvis, invariably a separation through or adjacent to the cartilaginous growth plate. Torode II (iliac wing fractures): Resulting from a direct lateral force against the pelvis, causing a disruption of the iliac apophysis or an infolding fracture of the wing of the ilium. Torode III-A (simple anterior ring fractures): This group involved only children with stable anterior fractures involving the pubic rami or pubic symphysis. Torode III-B (stable anterior and posterior ring fractures): This new group involved children with both anterior and posterior ring fractures that were stable. Torode IV (unstable ring disruption fractures): This group of children had unstable pelvic fractures, including ring disruptions, hip dislocations, and combined pelvic and acetabular fractures.
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Figure 25-5
The modified Torode and Zieg classification.
Torode I (avulsion fractures): avulsion of the bony elements of the pelvis, invariably a separation through or adjacent to the cartilaginous growth plate. Torode II (iliac wing fractures): Resulting from a direct lateral force against the pelvis, causing a disruption of the iliac apophysis or an infolding fracture of the wing of the ilium. Torode III-A (simple anterior ring fractures): This group involved only children with stable anterior fractures involving the pubic rami or pubic symphysis. Torode III-B (stable anterior and posterior ring fractures): This new group involved children with both anterior and posterior ring fractures that were stable. Torode IV (unstable ring disruption fractures): This group of children had unstable pelvic fractures, including ring disruptions, hip dislocations, and combined pelvic and acetabular fractures.
(From Shore BJ, Palmer CS, Bevin C, et al. Pediatric pelvic fracture: A modification of a preexisting classification. J Pediatr Orthop. 2012; 32(2):162–168.)
Torode I (avulsion fractures): avulsion of the bony elements of the pelvis, invariably a separation through or adjacent to the cartilaginous growth plate. Torode II (iliac wing fractures): Resulting from a direct lateral force against the pelvis, causing a disruption of the iliac apophysis or an infolding fracture of the wing of the ilium. Torode III-A (simple anterior ring fractures): This group involved only children with stable anterior fractures involving the pubic rami or pubic symphysis. Torode III-B (stable anterior and posterior ring fractures): This new group involved children with both anterior and posterior ring fractures that were stable. Torode IV (unstable ring disruption fractures): This group of children had unstable pelvic fractures, including ring disruptions, hip dislocations, and combined pelvic and acetabular fractures.
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Silber and Flynn81 reviewed radiographs of 133 children and adolescents with pelvic fractures and classified them into two groups: Immature (Risser 0 and all physes open) and mature (closed triradiate cartilage). They suggested that in the immature group, management should focus on the associated injuries because the pelvic fractures rarely required surgical intervention compared to the group with mature pelvises. Fractures in the mature group were best classified and treated according to adult pelvic fracture classification and management principles.7,63,91 
Quinby65 and Rang47 classified pelvic fractures in children into three categories: (i) Uncomplicated or mild fractures, (ii) fractures with visceral injury requiring surgical exploration, and (iii) fractures with immediate, massive hemorrhage often associated with multiple and severe pelvic fractures. This classification system emphasizes the importance of the associated soft tissue injuries, but does not account for the mechanism of injury or the prognosis of the pelvic fracture itself. Watts98 classified pediatric pelvic fractures according to the severity of skeletal injury: (a) Avulsion, caused by violent muscular contraction across the unfused apophysis; (b) fractures of the pelvic ring (secondary to crushing injuries), stable and unstable; and (c) acetabular fracture associated with hip dislocation. 

Adult Pelvic Fracture Classifications

Pennal et al.60 classified adult pelvic fractures according to the direction of force producing the injury: (a) AP compression, (b) lateral compression with or without rotation, and (c) vertical shear. This classification was modified and expanded by Tile et al. (Table 25-2).94 Burgess et al.7 further modified the Pennal system and incorporated subsets to the lateral compression and AP compression groups to quantify the amount of force applied to the pelvic ring. They also created a fourth category, combined mechanical injury, to include injuries resulting from combined forces that may not be strictly categorized according to the classification scheme of Pennal. 
 
Table 25-2
Tile and Pennal Classification of Pelvic Fractures
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Table 25-2
Tile and Pennal Classification of Pelvic Fractures
  1.  
    Stable fractures
    •  
      A1. Avulsion fractures
    •  
      A2. Undisplaced pelvic ring or iliac wing fractures
    •  
      A3. Transverse fractures of the sacrum and coccyx
  2.  
    Partially unstable fractures
    •  
      B1. Open-book fractures
    •  
      B2. Lateral compression injuries (includes triradiate injury)
    •  
      B3. Bilateral type B injuries
  3.  
    Unstable fractures of the pelvic ring
    •  
      C1. Unilateral fractures
    •  
       C1-1. Fractures of the ilium
      •  
         C1-2. Dislocation or fracture-dislocation of the sacroiliac joint
      •  
         C1-3. Fractures of the sacrum
    •  
      C2. Bilateral fractures, one type B and one type C
    •  
      C3. Bilateral type C fractures
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The Tile classification has been incorporated into the Orthopaedic Trauma Association/AO classification, which is divided into bone segments, types, and groups (Table 25-3).63 The Orthopaedic Trauma Association/AO system classifies pelvic fractures on the basis of stability versus instability, and surgical indications are based on the fracture types. Surgery is rarely indicated for type A fractures, whereas anterior and/or posterior surgical stabilization may be indicated for type B and C fractures. Numerous subtypes are included, and further details are described in the chapter on adult pelvic fractures. 
Table 25-3
AO/Association for the Study of Internal Fixation Classification of Pelvic Fractures
  1.  
    Stable fractures
  2.  
    Rotationally unstable fractures, vertically stable
  3.  
    Rotationally and vertically unstable fractures
    •  
      C1. Unilateral posterior arch disruption
      •  
        C1-1. Iliac fracture
      •  
        C1-2. Sacroiliac fracture-dislocation
      •  
        C1-3. Sacral fracture
    •  
      C2. Bilateral posterior arch disruption, one side vertically unstable
    •  
      C3. Bilateral injury, both unstable
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In general, the basic classifications, (a) mature or immature pelvis and (b) stable or unstable fracture, are very useful for making treatment decisions. Regardless of the classification system that is used, if there is a break in the anterior and posterior pelvic ring, an extremely misshapen pelvis, a displaced posterior ring injury, or a displaced triradiate fracture, the pelvis is unstable. 

Acetabular Fracture Classification

Pediatric Classifications. Bucholz et al.6 classified pediatric acetabular fractures based on the Salter–Harris classification (Fig. 25-6). Their classification system is used to help determine the prognosis of a triradiate cartilage injury that may result in a deformity of the acetabulum with growth. The anatomy of the triradiate is such that the superior weight-bearing portion of the acetabulum is separated from the inferior third by the superior arms of the triradiate cartilage. These superior arms are usually the ones involved in a fracture. In the Bucholz classification, a type I or II injury occurs from a traumatic force to the ischial ramus, pubic ramus, or proximal femur resulting in a shearing force through the superior arms of the triradiate cartilage. If there is a metaphyseal bone fragment, this is a type II fracture. A type V injury is a crush injury to the physis.6,45,98 Watts98 described four types of acetabular fractures in children: (i) Small fragments that most often occur with dislocation of the hip, (ii) linear fractures that occur in association with pelvic fractures without displacement and usually are stable, (iii) linear fractures with hip joint instability, and (iv) fractures secondary to central fracture-dislocation of the hip. 
Figure 25-6
Types of triradiate cartilage fractures.
 
A: Normal triradiate cartilage. B: Salter–Harris type I fracture.
A: Normal triradiate cartilage. B: Salter–Harris type I fracture.
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Figure 25-6
Types of triradiate cartilage fractures.
A: Normal triradiate cartilage. B: Salter–Harris type I fracture.
A: Normal triradiate cartilage. B: Salter–Harris type I fracture.
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Adult Acetabular Fractures

Acetabular fractures in children can also be described similarly to those in adults, which are usually classified by the system of Judet et al.37 and Letournel and Judet.44 A more comprehensive system is the AO fracture classification, which groups all fractures into A, B, and C types with increasing severity. Type A acetabular fractures involve a single wall or column; type B fractures involve both columns (transverse or T-types) and a portion of the dome remains attached to the intact ilium; and type C fractures involve both columns and separate the dome fragment from the axial skeleton by a fracture through the ilium. Both of these classification systems are discussed in more detail in Rockwood and Green's, Fractures in Adults, Chapter 36, Volume 2.68 

Outcome Measures for Pelvic and Acetabular Fractures

Outcome data has been assessed by several functional assessments. A national multicenter study is currently tracking outcomes using the WeeFim functional assessment.58 Other measures used to evaluate the quality of life in trauma patients include the Child Health Questionnaire (CHQ), the Functional Independence Measure, the Impact of Family Scale,76 and the Health Related Quality of Life (HRQOL) scale.75 Preliminary results demonstrate that 6-month functional scores after injury approach baseline levels,58 despite the increased patient and family stress encountered. 

Pathoanatomy and Applied Anatomy Relating to Pelvic and Acetabular Fractures

Pelvic and Acetabular Development

The pelvis of a child arises from three primary ossification centers: The ilium, ischium, and pubis. The three centers meet at the triradiate cartilage and fuse at approximately 12 to 14 years of age (Fig. 25-7).59 The pubis and ischium fuse inferiorly at the pubic ramus at 6 or 7 years of age. Occasionally, at approximately the time of fusion of the ischium to the pubis, an asymptomatic lucent area is noted on radiographs in the midportion of the inferior pubic ramus, termed the ischiopubic synchondrosis. It is often bilateral, fuses completely in most children, and may be confused with an acute or stress fracture of the pelvis. 
Figure 25-7
 
A: Triradiate-acetabular cartilage complex viewed from the lateral side, showing the sites occupied by the iliac, ischial, and pubic bones. B: Normal acetabular cartilage complex of a 1-day-old infant. The ilium, ischium, and pubis have been removed with a curette. The lateral view shows the cup-shaped acetabulum.
 
(From Ponseti IV. Growth and development of the acetabulum in the normal child. Anatomical, histological, and roentgenographic studies. J Bone Joint Surg Am. 1978; 60(5):575–585, with permission.)
A: Triradiate-acetabular cartilage complex viewed from the lateral side, showing the sites occupied by the iliac, ischial, and pubic bones. B: Normal acetabular cartilage complex of a 1-day-old infant. The ilium, ischium, and pubis have been removed with a curette. The lateral view shows the cup-shaped acetabulum.
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Figure 25-7
A: Triradiate-acetabular cartilage complex viewed from the lateral side, showing the sites occupied by the iliac, ischial, and pubic bones. B: Normal acetabular cartilage complex of a 1-day-old infant. The ilium, ischium, and pubis have been removed with a curette. The lateral view shows the cup-shaped acetabulum.
(From Ponseti IV. Growth and development of the acetabulum in the normal child. Anatomical, histological, and roentgenographic studies. J Bone Joint Surg Am. 1978; 60(5):575–585, with permission.)
A: Triradiate-acetabular cartilage complex viewed from the lateral side, showing the sites occupied by the iliac, ischial, and pubic bones. B: Normal acetabular cartilage complex of a 1-day-old infant. The ilium, ischium, and pubis have been removed with a curette. The lateral view shows the cup-shaped acetabulum.
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Secondary centers of ossification arise in the iliac crest, ischium, anterior-inferior iliac spine, pubic tubercle, angle of the pubis, ischial spine, and the lateral wing of the sacrum. Secondary ossification of the iliac crest is first seen at age 13 to 15 years and fuses to the ilium by age 15 to 17 years. The secondary ossification center of the ischium is first seen at 15 to 17 years and fuses at 19 years of age, although in some young adults it may fuse as late as 25 years of age. A center of ossification appears at the anterior-inferior iliac spine at approximately 14 years, fusing at 16 years of age.59,98 Knowledge about the location, age of appearance, and fusion of the secondary centers are important in differentiating these centers from fractures and avulsion injuries. 
The acetabulum contains the shared physes of the ilium, ischium, and pubis that merge to become the triradiate cartilage. Interstitial growth in the triradiate part of the cartilage complex causes the acetabulum to expand during growth and causes the pubis, ischium, and ilium to enlarge as well. The concavity of the acetabulum develops in response to the presence of a spherical head. The depth of the acetabulum increases during development as the result of interstitial growth in the acetabular cartilage, appositional growth of the periphery of this cartilage, and periosteal new bone formation at the acetabular margin.64 The triradiate cartilage of the acetabulum closes at approximately 12 years of age in girls and 14 years of age in boys.95 At puberty, three secondary centers of ossification appear in the hyaline cartilage surrounding the acetabular cavity. The os acetabuli, which is the epiphysis of the pubis, forms the anterior wall of the acetabulum. The epiphysis of the ilium, the acetabular epiphysis64,98 forms a large part of the superior wall of the acetabulum. The small secondary center of the ischium is rarely seen. The os acetabuli, the largest part, starts to develop at approximately 8 years of age and expands to form the major portion of the anterior wall of the acetabulum; it unites with the pubis at approximately 18 years of age. The acetabular epiphysis develops in the iliac acetabular cartilage at approximately 8 years and fuses with the ilium at 18 years of age, forming a substantial part of the superior acetabular joint surface (Fig. 25-8). The secondary center of the ischium, the smallest of the three, develops in the ninth year, unites with the acetabulum at 17 years, and contributes very little to acetabular development. These secondary centers are sometimes confused with avulsion fractures or loose bodies in the hip joint. 
Figure 25-8
Right innominate bone of an adolescent.
 
The os acetabuli (OA) is shown within the acetabular cartilage adjoining the pubic bone (PB); the acetabular epiphysis (AE), within the acetabular cartilage adjoining the iliac bone; and another small epiphysis (not labeled), within the acetabular cartilage adjoining the ischium (left).
 
(From Ponseti IV. Growth and development of the acetabulum in the normal child. Anatomical, histological, and roentgenographic studies. J Bone Joint Surg Am. 1978; 60(5):575–585, with permission.)
The os acetabuli (OA) is shown within the acetabular cartilage adjoining the pubic bone (PB); the acetabular epiphysis (AE), within the acetabular cartilage adjoining the iliac bone; and another small epiphysis (not labeled), within the acetabular cartilage adjoining the ischium (left).
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Figure 25-8
Right innominate bone of an adolescent.
The os acetabuli (OA) is shown within the acetabular cartilage adjoining the pubic bone (PB); the acetabular epiphysis (AE), within the acetabular cartilage adjoining the iliac bone; and another small epiphysis (not labeled), within the acetabular cartilage adjoining the ischium (left).
(From Ponseti IV. Growth and development of the acetabulum in the normal child. Anatomical, histological, and roentgenographic studies. J Bone Joint Surg Am. 1978; 60(5):575–585, with permission.)
The os acetabuli (OA) is shown within the acetabular cartilage adjoining the pubic bone (PB); the acetabular epiphysis (AE), within the acetabular cartilage adjoining the iliac bone; and another small epiphysis (not labeled), within the acetabular cartilage adjoining the ischium (left).
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Child Versus Adult Pelvis

As mentioned previously, there are important anatomic differences between the pelvis of a child and that of an adult (Table 25-4). Because of some of these differences, the pediatric pelvis is better able to absorb energy without significant displacement. Minimally displaced fractures and single breaks of the ring are frequently seen in pediatric pelvic fractures, a finding opposed to the traditional concept of a mandatory “double break” in the ring seen in adult fractures.47,59 More importantly, a child may sustain a higher energy injury than suspected from the bony injury, making it crucial that the surgeon be aware that even minor pelvic fractures may be associated with other potentially serious injuries. 
Table 25-4
Characteristics of the Pediatric Pelvis that Distinguish it from the Adult Pelvis
  1.  
    Greater bone plasticity and ligament elasticity that permits more bone deformation and greater mobility of the SI joints and symphysis pubis with trauma.
  2.  
    Thick periosteum, structural cartilage components, including the triradiate cartilage that also permit more mobility of the ring but are susceptible to growth disturbance.
  3.  
    The presence of bone–cartilage apophyses toward the end of skeletal growth that are susceptible to avulsion fractures from violent contraction of attached muscles.
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Treatment Options for Stable Pelvic Fractures

Avulsion Fractures (Torode and Zieg Type I)

Nonoperative Treatment

Of the 268 pelvic avulsion fractures reported in the four largest series,18,21,70,88 50% were ischial avulsions, 23% were avulsions of the anterior-superior iliac spine, 22% were avulsions of the anterior-inferior iliac spine, and 2% were avulsion of the iliac apophysis. Athletes who participate in jumping sports also sustain avulsions of the lesser trochanter from traction by the iliopsoas muscle, injuries that are often reported with pelvic apophyseal avulsion fractures (although more accurately a femur fracture) (Fig. 25-9). Most pelvic avulsion fractures in children heal satisfactorily with nonoperative management including rest, partial weight bearing on crutches for 2 or more weeks, and extremity positioning to minimize muscle stretch. Typically children resume normal activities by 6 to 8 weeks. Two small series of adolescents with pelvic avulsion fractures treated conservatively concluded that nonsurgical treatment was successful in all patients, and all patients returned to preinjury activity levels.18,53 In another series, only 3 of 198 competitive adolescent athletes with pelvic avulsion fractures were treated operatively.70 
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Figure 25-9
Avulsion fracture of the lesser trochanter.
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Others, however, have suggested that nonoperative treatment is associated with a higher incidence of functional disability and inability to return to competitive athletic activity.88 In one long-term follow-up study of 12 patients with ischial avulsions, 8 reported significant reduction in athletic ability and 5 had persistent local symptoms.73 Thus, some controversy exists surrounding the acute management of displaced ischial avulsion fractures. Although many have satisfactory outcomes without surgery, indications for surgical management are not clear nor is the best operative technique established. Most agree that excision of the ischial apophysis is indicated in the setting of chronic pain and disability. Some authors, however, recommend open reduction and internal fixation of those rare acute ischial avulsion fragments displaced more than 1 to 2 cm (Fig. 25-10).46 Operative treatment of the other types of avulsion fractures is rarely indicated. 
Figure 25-10
 
A: A painful ischial apophyseal nonunion in an athlete. B: Fixation of the apophysis. C: Healed apophysis after implant removal.
 
(Courtesy of Dr. David C Scher, Hospital for Special Surgery, NY.)
A: A painful ischial apophyseal nonunion in an athlete. B: Fixation of the apophysis. C: Healed apophysis after implant removal.
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Figure 25-10
A: A painful ischial apophyseal nonunion in an athlete. B: Fixation of the apophysis. C: Healed apophysis after implant removal.
(Courtesy of Dr. David C Scher, Hospital for Special Surgery, NY.)
A: A painful ischial apophyseal nonunion in an athlete. B: Fixation of the apophysis. C: Healed apophysis after implant removal.
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Operative Treatment

Indications/Contraindications. Most avulsion fractures may be successfully treated nonsurgically. Significant displacement greater than 1 to 2 cm, persistent pain, or bony prominence that interferes with sitting are all relative indications for surgery. 

Ischial Avulsion Fracture

Preoperative planning checklist includes: 
  1.  
    C-arm
  2.  
    Fluoroscopic table such as a Jackson table
  3.  
    Screw set including 4.5- to 6.5-mm screws with washers
  4.  
    Cables, wires, and/or suture anchors available as a back up
Positioning: prone surgical approach for open reduction and internal fixation of an ischial avulsion fracture. 
After appropriate anesthesia, the patient should be placed in a prone position with the hip and knee slightly flexed. An approximately 7- to 10-cm incision is made along the gluteal crease. The inferior edge of the gluteus maximus is identified and elevated. The plane between gluteus maximus and the hamstring muscles is then developed as the gluteus maximus is traced proximally. The bony fragment with the hamstrings attached is identified. Radiographs or C-arm can be used to identify this more clearly if needed. The fragment may be reduced more easily with the hip extended and the knee slightly flexed. After reduction, the fragment is stabilized with cancellous screws, with or without washers. If necessary, additional fixation with suture anchors, cables, or wires may be needed to ensure stability. 

Postoperative Care

After surgery, the patient is permitted to sit up with the hips and knees slightly flexed to decrease stress on the hamstrings. Initially made nonweight bearing, patients may progress to full weight bearing in 3 to 6 weeks. At 12 weeks postoperatively, the patient may resume full activities. 

Isolated Iliac Wing Fractures (Torode and Zeig Type II)

Direct trauma may fracture the wing of the ilium, but isolated iliac wing fractures are relatively rare, with a reported incidence of 5% to 14% in children with fractures of the pelvis.66,69,80 However, iliac wing fractures often occur in conjunction with other fractures of the pelvis, and thus the overall incidence of iliac wing fractures is significantly higher than the incidence of isolated iliac wing fractures. 
The patient with an iliac wing fracture typically presents with pain that is located over the wing of the ilium. On examination, motion at the fracture site may be noted. A painful Trendelenburg gait may be present because of spasm of the hip abductor muscles. A fracture of the wing of the ilium may be overlooked on an underexposed radiograph of the pelvis where the ilium is poorly seen as a large area of radiolucency. Displacement of the fracture usually occurs laterally, but it may occur medially or proximally. Severe displacement is rare because the iliac wing is tethered by the abdominal muscles and the hip abductors. 
Treatment of an iliac wing fracture is mostly dictated by the associated injuries. Symptomatic treatment is all that is necessary for most iliac wing fractures and typically includes pain management and partial weight bearing on crutches until the symptoms are completely resolved. Regardless of comminution or displacement, these fractures usually unite without complications or sequelae (Fig. 25-11). Open reduction with screws or plating is rarely indicated except for large fragments with severe displacement. 
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Figure 25-11
Stable fracture of the iliac wing.
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Other Stable Fractures

Fractures of the Sacrum

Sacral fractures constitute a small fraction of pelvic fractures reported in children. Rieger and Brug69 reported two sacral fractures and seven sacroiliac fracture-dislocations in their 54 patients. Sacral fractures are probably more common than reported, but because they are obscured by the bony pelvis and the soft tissue shadows of the abdominal viscera, and because they are rarely displaced, they may be overlooked. Nine of 166 patients (5.4%) with pelvic fractures in the series by Silber et al.83 had associated sacral fractures, none with nerve root involvement. There are two general types of sacral injuries. Spinal-type injuries may present as crush injury with vertical foreshortening of the sacrum or horizontal fractures across the sacrum. These fractures may be significant because they may damage the sacral nerves, resulting in the loss of bowel and bladder function. Alar-type injuries are generally vertical fractures through the ala or foramina. These fractures are significant in that they may represent the posterior break of the double ring fracture. 
The presence of sacral fractures may be suggested clinically. Pain and swelling may be present, usually over the sacrum. Because digital rectal examination in pediatric trauma patients has a high false-negative rate, its usefulness is questionable and is not routinely performed in all centers.79 When the examination is performed in patients with sacral fractures, fracture fragments, rectal tears, and urethral disruptions may sometimes be identified. 
Sacral fractures are difficult to see on plain radiographs. The fracture can be oblique, but most are transverse with minimal displacement and occur through a sacral foramen, which is the weakest part of the body of the sacrum. Minimal offset of the foramen or offset of the lateral edge of the body of the sacrum is an indication of sacral fracture. Lateral views are helpful only if there is anterior displacement, which is rare. A 35-degree caudal view of the pelvis may reveal a fracture of the body of the sacrum. CT and MRI scans are best in the identification of sacral fractures missed on plain radiographic images.24,27,77 In one study comparing radiographs with CT scans in a consecutive series of 103 pediatric trauma patients with pelvic radiographs and pelvic CT scans, only three sacral fractures were identified with plain radiographs whereas nine sacral fractures were identified with CT (Fig. 25-12).27 Sacral fractures are generally managed expectantly and treated symptomatically. In rare cases, pinched sacral nerve roots may need to be decompressed. 
Figure 25-12
 
A: An example of an anterior–posterior pelvic radiograph where the sacral fracture is not well visualized. B: CT scan of the patient showing the sacral fracture.
A: An example of an anterior–posterior pelvic radiograph where the sacral fracture is not well visualized. B: CT scan of the patient showing the sacral fracture.
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Figure 25-12
A: An example of an anterior–posterior pelvic radiograph where the sacral fracture is not well visualized. B: CT scan of the patient showing the sacral fracture.
A: An example of an anterior–posterior pelvic radiograph where the sacral fracture is not well visualized. B: CT scan of the patient showing the sacral fracture.
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Fractures of the Coccyx

Many children fall on the tailbone and have subsequent pain. The possibility of fracture must be entertained. Because the coccyx is made up of multiple small segments, is obscured by soft tissue, and naturally has a crook in it, it is difficult to determine on radiographs whether a coccygeal fracture has occurred, especially in a child. These fractures rarely have associated injuries. Clinically, patients describe immediate, severe pain in the area of the coccyx. Pain on defecation may be present as well as pain on rectal examination. Because radiographic identification is difficult, the diagnosis should be made clinically by digital rectal examination. Exquisite pain may be elicited, and an abnormal mobility of the coccygeal fragments may be noted. Acute symptoms may abate in 1 to 2 weeks, but may be remarkably persistent. The differential diagnosis is between fracture and coccydynia. Lateral radiographs of the coccyx with the hips flexed maximally may reveal a fracture (Fig. 25-13). Apex posterior angulation of the coccyx is a normal variant, and should not be falsely interpreted as a fracture or dislocation. CT and MRI scanning may be helpful in differentiating between physeal plates and fracture lines.13 Treatment is symptomatic only and consists of activity restriction and a pressure-relieving cushion for sitting with an expectation of resolution in 4 to 6 weeks for acute fractures. In our experience, however, some patients have chronic pain that persists for several months, probably better described by the diagnosis “coccydynia.” Symptomatic treatments, injections, and coccygectomy are some management options with good results in adolescents.26 
Figure 25-13
Lateral radiograph with the hips maximally flexed reveals a displaced coccygeal fracture in a 14-year-old boy.
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Stress Fractures of the Pubis or Ischium

Stress fractures are rare in small children, but they do occur in adolescents and young adults from chronic, repetitive stress to a bony area or during the last trimester of pregnancy. Stress fractures of the pubis are likewise uncommon, but a small series of stress fractures, primarily in the inferior pubic rami, has been reported. Chronic symptoms and pain increased by stress may be noted in the inferior pubic area. Radiographs may show no evidence of fracture for as long as 4 to 6 weeks, and then only faint callus formation may be visible; however, MRI or a technetium bone scan may reveal increased uptake early.34 Treatment should consist of avoiding the stressful activity and limited weight bearing for 4 to 6 weeks. 
The ischiopubic synchondrosis usually closes between 4 and 8 years of age.40 The radiographic appearance of the synchondrosis at the ischiopubic junction may be misinterpreted as a fracture. Caffey and Ross8,42 noted that bilateral fusion of the ischiopubic synchondrosis is complete in 6% of children at 4 years of age and in 83% of children at 12 years of age. The presence of the synchondrosis itself is common and usually asymptomatic. Bilateral swelling of the synchondrosis was also noted in 47% of children at age 7 years. Irregular ossification and clinical swelling at the ischiopubic synchondrosis has been called ischiopubic osteochondritis or van Neck disease. If this syndrome is noted in a child older than 10 years of age, it should be treated as a repetitive stress injury (Fig. 25-14). 
Figure 25-14
Radiograph of the pelvis of a 9-year-old child.
 
Although the differentiation could not be made between a fracture and fusion of the right ischiopubic ossification at the time of radiograph, the patient was asymptomatic and the mass was considered a variant of normal development.
Although the differentiation could not be made between a fracture and fusion of the right ischiopubic ossification at the time of radiograph, the patient was asymptomatic and the mass was considered a variant of normal development.
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Figure 25-14
Radiograph of the pelvis of a 9-year-old child.
Although the differentiation could not be made between a fracture and fusion of the right ischiopubic ossification at the time of radiograph, the patient was asymptomatic and the mass was considered a variant of normal development.
Although the differentiation could not be made between a fracture and fusion of the right ischiopubic ossification at the time of radiograph, the patient was asymptomatic and the mass was considered a variant of normal development.
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Treatment Options for Unstable Pelvic and Acetabular Fractures

Simple Ring Fractures (Torode and Zieg Type III A and B)

Based on the original classification scheme, simple ring injuries constitute up to 56% of all pelvic fractures in children,46,50,63,77 with the majority resulting from motor vehicles striking pedestrians.81 Many of these reported injuries were breaks in the anterior pelvic ring and were single ramus fractures—most commonly fractures of the superior ramus (Fig. 25-15).46 In evaluating the usefulness of the classification subsequent to the original description and with the increased use of CT scans to define these injuries, it became apparent that not all stable pelvic ring injuries are the same with regard to fracture pattern, mechanism, associated injuries, or prognosis. To reflect important differences among the types of simple ring injuries, Shore et al., working with Torode from the original classification, modified the Torode and Zeig scheme. In the modified classification, type III stable or simple ring fractures are subdivided into types IIIa and IIIb. Type IIIa fractures are defined as simple anterior ring fractures and type IIIb fractures are stable anterior and posterior ring fractures. This distinction is critical because type IIIb injuries are associated with an increased need for blood transfusions, an increased length of hospital stay, more frequent admissions to the ICU, and more associated injuries compared to type IIIa fractures. 
Figure 25-15
 
A: Stable superior pubic ramus fracture. The patient was allowed full weight bearing as tolerated. B: Radiographs show complete fracture union and remodeling.
A: Stable superior pubic ramus fracture. The patient was allowed full weight bearing as tolerated. B: Radiographs show complete fracture union and remodeling.
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Figure 25-15
A: Stable superior pubic ramus fracture. The patient was allowed full weight bearing as tolerated. B: Radiographs show complete fracture union and remodeling.
A: Stable superior pubic ramus fracture. The patient was allowed full weight bearing as tolerated. B: Radiographs show complete fracture union and remodeling.
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Nonsurgical Treatment

Patients with these injuries typically present with pain and tenderness about the pubic rami. Weight bearing is difficult or impossible secondary to pain and hip range of motion is often limited because of muscle guarding around the hip. The pelvic ring is grossly stable to rocking and compression but, for patients with type IIIb injuries, tenderness along the sacrum and sacroiliac joints may be elicited with palpation. Pelvic inlet and outlet radiographic views, or more commonly a CT scan, are used to distinguish type IIIa from type IIIb fractures. 
Most stable ring fractures require no surgical intervention for management of the pelvic ring injury because, by definition, the pelvic ring is stable. For patients with type IIIb fractures, monitoring of cardiovascular status and blood loss, and management of associated injuries are priorities compared to pelvic fracture management. Most patients with type III fractures, however, require only symptomatic treatment. Pain control and mobilization out of bed with nonweight bearing or protected weight bearing, as dictated but the status of associated injuries when present, is important for the initial 1 to 2 weeks after injury. After pelvic ring healing has progressed and the pain has diminished, progressive weight bearing is permitted. Most children with type III pelvic fractures return to full activities within 6 to 8 weeks of the initial injury, unless associated comorbidities influence recovery. 

Special Situations

Fractures of the Two Ipsilateral Rami

Fractures of the ipsilateral superior and inferior pubic rami comprised 18% of pediatric pelvic fractures in one series of 120 pediatric pelvic fractures.11 Although these fractures are generally stable, they may be associated with injuries of the abdominal viscera, especially the genitourinary system (e.g., bladder rupture).17 A careful examination of the perineum, rectal examination, and a cystourethrogram may be indicated to fully assess these injuries. Because these fractures typically unite without surgical treatment, most are treated nonsurgically except when severe displacement has occurred. 

Fractures of the Body of the Ischium

Fracture of the body of the ischium near the acetabulum is extremely rare in children. The fracture occurs from external force to the ischium, most commonly in a fall from a considerable height. The fracture usually is minimally displaced and management consists of symptomatic treatment and progressive weight bearing (Fig. 25-16). 
Figure 25-16
 
A: Nondisplaced fracture (curved arrow) through left ischium and contralateral pubic ramus fracture. B: Follow-up radiograph shows mild displacement and incongruity of the acetabulum and complete healing of the superior pubic ramus fracture. Either displacement of the fracture fragments or premature closure of the triradiate cartilage could have contributed to the incongruity of the femoral head in the acetabulum.
A: Nondisplaced fracture (curved arrow) through left ischium and contralateral pubic ramus fracture. B: Follow-up radiograph shows mild displacement and incongruity of the acetabulum and complete healing of the superior pubic ramus fracture. Either displacement of the fracture fragments or premature closure of the triradiate cartilage could have contributed to the incongruity of the femoral head in the acetabulum.
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Figure 25-16
A: Nondisplaced fracture (curved arrow) through left ischium and contralateral pubic ramus fracture. B: Follow-up radiograph shows mild displacement and incongruity of the acetabulum and complete healing of the superior pubic ramus fracture. Either displacement of the fracture fragments or premature closure of the triradiate cartilage could have contributed to the incongruity of the femoral head in the acetabulum.
A: Nondisplaced fracture (curved arrow) through left ischium and contralateral pubic ramus fracture. B: Follow-up radiograph shows mild displacement and incongruity of the acetabulum and complete healing of the superior pubic ramus fracture. Either displacement of the fracture fragments or premature closure of the triradiate cartilage could have contributed to the incongruity of the femoral head in the acetabulum.
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Widening of the Symphysis Pubis

Isolated injuries to the symphysis pubis are rare because these typically occur in association with disruption of the posterior ring at or near the sacroiliac joint most commonly. Although significant force appears to be necessary to disrupt or fracture the symphysis pubis, isolated disruption of the symphysis pubis can occur.98 Clinically, exquisite pain is present anteriorly at the symphysis. The lower extremities may lie externally rotated when the patient is supine. Motion of the hips in flexion, abduction, external rotation, and extension is restricted and painful (FABER sign). Pain associated with a pubic diastasis is often improved by side-lying compared to supine positioning.98 
Radiographs and CT imaging may reveal subluxation or widening of the symphysis or in the bone of the anterior ring just adjacent to it, and vertical or anterior–posterior offset of the two sides of the symphysis.90 Although some elasticity of the pubic symphysis is normal in children and adolescents, diastasis greater than or equal to 2.5 cm or rotational deformity greater than 15 degrees suggests significant instability and is an indication for reduction.23 Because of the normal variation of the width of the symphysis in children, the extent of traumatic separation may be difficult to evaluate. Watts98 suggested obtaining radiographs with and without lateral compression of the pelvis to detect abnormalities, with greater than 1 cm of difference in the width of the symphysis pubis between the two views indicating a symphyseal separation. Imaging must also be carefully scrutinized to detect sacroiliac joint disruptions and triradiate cartilage fractures, both of which may occur in association with symphysis pubis separation (Fig. 25-17).59 
Figure 25-17
 
A: Fracture adjacent to the symphysis pubis with symphysis pubis separation. B: CT scan showing no posterior instability.
A: Fracture adjacent to the symphysis pubis with symphysis pubis separation. B: CT scan showing no posterior instability.
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Figure 25-17
A: Fracture adjacent to the symphysis pubis with symphysis pubis separation. B: CT scan showing no posterior instability.
A: Fracture adjacent to the symphysis pubis with symphysis pubis separation. B: CT scan showing no posterior instability.
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Treatment of an isolated injury of the symphysis pubis with less than 2 cm of diastasis is generally symptomatic, similar to that described above for other stable pelvic ring injuries. Wider diastasis is best treated with closed reduction and external fixation (2) or open reduction and plating of the symphysis through an anterior Pfannenstiel incision (Fig. 25-18). 
Figure 25-18
Radiograph of the pelvis after plating of the pubic symphysis that also includes acetabular fixation.
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Isolated Fractures Near or Through the Sacroiliac Joint

Isolated posterior ring disruptions near or through the sacroiliac joint are rare in children. More commonly, posterior disruptions of the pelvic ring occur in conjunction with disruption of the anterior pelvis. Sacroiliac dislocations differ from those in adults in important ways. In children, disruptions tend to be incomplete because the anterior sacroiliac ligaments rarely tear through the entire ligament complex. In addition, the sacroiliac joint injury may separate, not through the joint, but instead through the physis of the ilium adjacent to the joint.59 This fracture, through the relatively weak physeal cartilage, technically leaves the sacroiliac joint intact.15 
Derangement of the sacroiliac joint should be suspected after high-velocity trauma with impact to the posterior pelvis. In patients with these injuries, the FABER sign is typically markedly positive on the ipsilateral side.15,18 Associated vascular and neurologic injuries may occur. Lumbosacral nerve root avulsions have been described in children with this fracture.15 Radiographs, particularly inlet and outlet pelvic views, and axial CT imaging, reveal subtle asymmetry of the iliac wings or the clear spaces that demarcate the sacroiliac joints. Offset of the distal articular surface is an indication of sacroiliac joint disruption (Fig. 25-19). 
Figure 25-19
A 4-year old with a pelvic fracture primarily with posterior involvement.
 
A: Pelvic outlet radiograph showing a posterior injury at the sacroiliac joint. B: CT scan showing the minimal posterior SI widening. C: CT scan showing no anterior ring injury.
A: Pelvic outlet radiograph showing a posterior injury at the sacroiliac joint. B: CT scan showing the minimal posterior SI widening. C: CT scan showing no anterior ring injury.
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A: Pelvic outlet radiograph showing a posterior injury at the sacroiliac joint. B: CT scan showing the minimal posterior SI widening. C: CT scan showing no anterior ring injury.
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Figure 25-19
A 4-year old with a pelvic fracture primarily with posterior involvement.
A: Pelvic outlet radiograph showing a posterior injury at the sacroiliac joint. B: CT scan showing the minimal posterior SI widening. C: CT scan showing no anterior ring injury.
A: Pelvic outlet radiograph showing a posterior injury at the sacroiliac joint. B: CT scan showing the minimal posterior SI widening. C: CT scan showing no anterior ring injury.
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A: Pelvic outlet radiograph showing a posterior injury at the sacroiliac joint. B: CT scan showing the minimal posterior SI widening. C: CT scan showing no anterior ring injury.
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Symptomatic treatment and limited weight bearing on crutches are sufficient treatments for most isolated subluxations or fractures involving the sacroiliac joint. In one report,31 isolated sacroiliac joint dislocations were treated in 18 children, 10 of whom had extensive degloving injuries of the posterior pelvis. While 10 patients were treated with nonsurgical treatment, 8 required surgery. The majority of these patients underwent open reduction and plate fixation. Based on this report, outcomes for this injury are not uniformly good, with nearly all patients experiencing complications such as chronic pain and incomplete recovery of nerve root injuries. 

Ring Disruption: Unstable Fracture Patterns (Torode and Zieg Type IV)

Unstable pelvic fractures in children and adolescents constitute a small percentage of all pelvic fractures in pediatric patients. In one series of pelvic ring fractures, type IV injuries represented 10% of all pelvic fractures seen.80 Most of these injuries result from high-velocity trauma, such as motor vehicle collisions and pedestrians being struck by motor vehicles. Children older than 12 years of age and those with closed triradiate cartilages80,81 are more likely to sustain these types of fractures compared to younger patients and those with open triradiate cartilages about the pelvis. Blood transfusions, intensive care unit lengths of stay, and surgical interventions, among other parameters, are generally increased in patients with type IV fractures compared to other types of pelvic fractures, as is the incidence of death. 
Type IV fractures are typically divided into three subcategories: 
  1.  
    Double anterior ring disruptions. This injury subtype includes bilateral pubic rami fractures (the straddle or floating injury) and disruptions of the pubis with an associated second break in the anterior ring.
  2.  
    Anterior and posterior pelvic ring (double ring) disruptions with instability and displacement, including vertical displacement (Malgaigne type). The anterior disruptions may be rami fractures or symphysis pubis disruption. Posterior ring injuries include fractures of the sacrum or ilium and disruptions through or adjacent to the sacroiliac joints.
  3.  
    Multiple crushing injuries that produce at least two severely comminuted fractures located at any site in the pelvic ring.

Bilateral Fractures of the Inferior and Superior Pubic Rami

Bilateral fractures of the inferior and superior pubic rami may occur in a fall while straddling a hard object, by lateral compression of the pelvis, or by sudden impact while riding a motorized cycle. The floating fragment usually is displaced superiorly, pulled in this direction by the rectus abdominis muscles.98 As with ipsilateral superior and inferior pubic rami fractures, which may occur by similar mechanisms, bladder, or urethral disruptions59 are commonly associated injuries that must be ruled out in patients with this type of pelvic fracture. 
Radiographically, an inlet view or CT scan most accurately determines the amount of true displacement. Bilateral fractures of the inferior and superior pubic rami (straddle fractures) or disruption of the symphysis pubis with unilateral fractures of the rami are two fracture patterns that result in a floating anterior segment of the pelvic ring. Although this floating anterior arch is inherently unstable (Fig. 25-20) the posterior ring is usually not disrupted except, in some cases, by stable fractures of the sacrum or ilium. 
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Figure 25-20
Example of a straddle fracture.
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Treatment

Because in most cases the posterior ring is intact and the anterior fractures are not displaced, treatment is similar to that described for type IIIb injuries. After associated injuries have been diagnosed and managed appropriately, treatment initially includes bed rest and pain control. Skeletal traction is unnecessary, and a pelvic sling is contraindicated because of the possibility that compression will cause medial displacement of the ilium.59,98 Protected weight bearing with progression to full weight bearing and unrestricted activities is then permitted as pain improves. In children, pelvic ring healing occurs reliably in 6 to 8 weeks for most injuries. Bone remodeling can be expected over the ensuing months. Surgical treatment of the superior ramus with screw fixation or plating techniques are rarely necessary to treat children but may be indicated in adolescents, especially for those with significant displacement. 

Anterior and Posterior Ring Disruptions

Double breaks in the pelvic ring, in which fractures occur both anterior and posterior to the acetabulum, (Fig. 25-21) result in instability of the pelvis. These injuries result from a variety of mechanisms. In one report,83 AP compression forces were suspected to be the mechanism of injury, although the exact forces were not readily defined in all patients. Other possible causes of injury are severe direct lateral compressive forces, indirect forces transmitted proximally along the femoral shaft with the hip fixed in extension and abduction, and combined mechanisms of injury in which the pelvis is subject to multiple forces from different directions. 
The left hemipelvis is displaced and rotated.
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Figure 25-21
An unstable pelvis fracture with fractures in both the anterior and posterior ring of the pelvis.
The left hemipelvis is displaced and rotated.
The left hemipelvis is displaced and rotated.
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These unstable fractures are often accompanied by retroperitoneal and intraperitoneal bleeding and are most likely to be associated with severe, life-threatening hemorrhage. Concomitant abdominal injury occurs with an incidence of 35% to 60% in patients with these unstable pelvic fractures compared to 11% to 18% of patients with stable pelvic fractures.4,96 
Aside from the physical signs usually associated with pelvic fractures, leg-length discrepancy and asymmetry of the pelvis may be present. Apparent leg-length discrepancy is seen in patients with vertical or cephalad displacement of the fractured hemipelvis. Internal or external rotation of the unstable hemipelvis may appear as asymmetry of the iliac crests. Inlet and outlet radiographs and CT scan reveal the amount of pelvic displacement. 

Treatment

Initial treatment is focused on cardiovascular resuscitation with fluids and blood products, and stabilization of the child's overall condition before treatment of the pelvic fractures.92 Pelvic binders or sheets, placed circumferentially across the greater trochanters to limit pelvic ring expansion with severe hemorrhage, may be used safely in larger children and adolescents with similar indications and precautions as in adults. Some injuries caused predominantly by lateral compression forces, however, may not be amenable to this because compression may increase the pelvic deformity. Embolization of arterial vessels is also an option for uncontrolled bleeding. Evidence-based literature regarding the use of pelvic binders and embolization in younger children is lacking, however, predominantly because unstable ring injuries that contribute to hemodynamic instability are exceedingly rare. The search for other sites of hemorrhage must be undertaken before attributing hemodynamic instability to the pelvic trauma in these younger children. 

Minimally Displaced Fractures

Treatment of the pelvic ring injury varies based on the fracture pattern, degree of displacement and the age and condition of the child. For fractures with minimal displacement regardless of fracture pattern or age, symptomatic treatment that includes pain control, weight-bearing restrictions, and close radiographic follow-up for displacement is satisfactory to achieve healing (Fig. 25-22). Spica casting can be used in the younger child to improve the comfort of the patient and to prevent weight bearing, after cardiovascular parameters and associated injures have been stabilized. In some cases, older children and adolescents with minimally displaced fractures benefit from fixation to lessen pain associated with the fracture and facilitate mobilization. The majority of minimally displaced fractures, however, are treated nonsurgically. 
Figure 25-22
A potentially unstable pelvic fracture with anterior and posterior injury.
 
A: The radiograph shows a left superior and inferior rami fractures. B: The CT scan shows a minimally displaced fracture adjacent to the sacroiliac joint. This is also an example where both CT and plan radiographs can be used to evaluate the injury and help decide on displacement and treatment. This patient was treated nonoperatively with follow-up making sure there was no displacement.
A: The radiograph shows a left superior and inferior rami fractures. B: The CT scan shows a minimally displaced fracture adjacent to the sacroiliac joint. This is also an example where both CT and plan radiographs can be used to evaluate the injury and help decide on displacement and treatment. This patient was treated nonoperatively with follow-up making sure there was no displacement.
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Figure 25-22
A potentially unstable pelvic fracture with anterior and posterior injury.
A: The radiograph shows a left superior and inferior rami fractures. B: The CT scan shows a minimally displaced fracture adjacent to the sacroiliac joint. This is also an example where both CT and plan radiographs can be used to evaluate the injury and help decide on displacement and treatment. This patient was treated nonoperatively with follow-up making sure there was no displacement.
A: The radiograph shows a left superior and inferior rami fractures. B: The CT scan shows a minimally displaced fracture adjacent to the sacroiliac joint. This is also an example where both CT and plan radiographs can be used to evaluate the injury and help decide on displacement and treatment. This patient was treated nonoperatively with follow-up making sure there was no displacement.
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Displaced Fractures

Nonsurgical Treatment.
Historically, operative treatment of pelvic fractures in children has not been routinely utilized because of the following: (a) Severe hemorrhage from the pelvic fracture is unusual in children, making operative pelvic stabilization to control bleeding rarely necessary2,55; (b) the thick periosteum and ligaments about the pelvis in children limit displacement and stabilize the fracture to some degree, limiting fracture fragment mobility and facilitating healing so that nonsurgical treatment is well tolerated by patients,66 and prolonged immobilization is not necessary for fracture healing56; (c) remodeling may occur in skeletally immature patients, reducing the need to achieve anatomic alignment of some fractures; and (d) with few exceptions, long-term morbidity after pelvic fractures is rare in children.25,38,55 
Techniques.
Nonoperative treatment for unstable pelvic fractures includes bedrest and spica cast immobilization, neither of which significantly improves fracture alignment. For children younger than 8 years of age, closed reduction and spica casting may be used for symphyseal disruptions and sacroiliac joint injuries with small degrees of displacement. Skeletal traction is the only nonsurgical treatment that can be used to improve alignment of widely displaced fractures. Unstable fractures with vertical displacement of the hemipelvis may be reduced with this modality. Longitudinal traction is applied through a pin placed in the distal femur with weights similar to those utilized for femoral shaft reduction, typically 5 to 7 lb or one-eighth of body weight depending on the size of the child. Postreduction imaging is used to assess reduction and progression of healing. Traction is applied for a minimum of 2 to 4 weeks to achieve some stability of the injury, after which the child may be placed in a spica or kept on bedrest until further healing allows safe mobilization. Skeletal traction cannot improve alignment of symphyseal “open book” injuries, severe sacroiliac disruptions with widening, or fractures with rotational deformities of the hemipelvis. 
Outcomes.
Despite the fact that the classic assumptions and observations regarding pelvic fractures are generally correct, the published outcomes of nonsurgical treatments have not been uniformly satisfactory. Nierenberg et al.56 reported excellent or good results after conservative treatment of 20 unstable pelvic fractures in children, despite radiographic evidence of deformity. These authors concluded that treatment guidelines for unstable pelvic fractures are not the same for children as for adults, and recommended that external or internal fixation should be used only when conservative methods fail.56 In another study,50 however, the authors found that a third of 15 skeletally immature patients with unstable fractures treated nonoperatively had chronic pain at follow-up. Similar findings were shown in another large series of unstable pediatric pelvic fractures treated nonsurgically with a mean of 7.4 years follow-up. In this study, about one-fourth of patients had musculoskeletal complaints at follow-up, including leg-length discrepancy, back pain, and sacroiliac ankylosis.85 In addition, these authors identified important nonorthopedic complications, including 23 patients with genitourinary abnormalities, such as incontinence and erectile dysfunction, and 31 patients with psychiatric diagnoses such as posttraumatic stress disorder and major depression. These authors stressed the importance of minimizing prolonged hospital stays, addressing urologic needs fully, and anticipating the need for mental health support. 
Surgical Treatment.
Because past results of nonsurgical treatment of unstable fractures have been mixed, surgical treatment of significantly displaced and unstable pediatric pelvic fractures has become the practice standard at many pediatric trauma centers. The development of reliable and safe surgical techniques that may be applied to children and the availability of experienced adult orthopedic trauma personnel may be responsible for the growing trend toward the surgical management of unstable pediatric pelvic fractures. 
In addition to the advantages of improved mobilization, anatomic or near-anatomic realignment of pelvic fractures likely improves outcomes. Residual pelvic ring asymmetry, specifically vertical displacement of the hemipelvis and sacroiliac joint malalignment, and acetabular deformity do not reliably remodel after fracture healing and have been associated with poor long-term outcomes such as leg-length discrepancy, back pain, scoliosis, and sacroiliac arthrosis in children.74,84,87 Pelvic obliquity and asymmetry has also been associated with pelvic floor dysfunction and pain. In one74 long-term follow-up study of 17 children with unstable pelvic fractures treated nonoperatively, 8 patients had pelvic asymmetry at follow-up. Of these eight patients, five had functional deformities, including scoliosis and leg-length discrepancies that resulted in chronic back pain. In another study, Smith et al.87 followed 20 patients with open triradiate cartilages who were treated for unstable pelvic fractures for a mean of 6.5 years. Pelvic asymmetry was quantified41 on an AP pelvis radiograph by measuring the difference in length (in centimeters) between two diagonal lines drawn from the border of the sacroiliac joint to the contralateral triradiate cartilage. Eighteen patients were treated operatively with external fixation, internal fixation, or a combination of both; pelvic asymmetry was less than 1 cm in 10 of 18 patients. At follow-up, the authors noted that pelvic asymmetry did not remodel to any significant degree, even in younger patients. Based on the Short Musculoskeletal Function Assessment (SMFA) questionnaire, patients with 1 cm or less of pelvic asymmetry had significantly less back and sacroiliac pain, and better SMFA outcome scores than those patients with pelvic asymmetry greater than 1 cm. In addition, all patients with greater than 1.1 cm of pelvic asymmetry had three or more of the following: nonstructural scoliosis, lumbar pain, a Trendelenburg sign, or sacroiliac joint tenderness and pain. The authors concluded that fractures associated with at least 1.1 cm of pelvic asymmetry following closed reduction should be treated with open reduction and internal or external fixation to improve alignment and the long-term functional outcome.87 
Because of concerns for poor outcomes based on prior experience with nonsurgical treatment of unstable pediatric pelvic fractures, Karunaker et al.39 surgically managed 18 unstable pelvic and acetabular fractures in children younger than 16 years of age using the principles of anatomic realignment and stable fixation routinely applied to adults. All patients healed by 10 weeks after surgery and had recovered full function with minimal residual pain at follow-up. No significant complications occurred, notably no cases of premature triradiate cartilage closure or sacroiliac joint abnormalities. They recommended operative intervention in skeletally immature patients with significant deformity of the pelvis at the time of injury to prevent late morbidities.39 Others have drawn similar conclusions based on their experience with surgical management of unstable pediatric pelvic disruptions.57,69,93 
Indications.
The exact indications for surgical treatment are not clearly delineated in the literature and are somewhat controversial. Holden et al.35 determined, after a review of the literature prior to 2006, that fractures with more than 2 cm of displacement must be reduced and stabilized in children. Others have suggested that pelvic asymmetry greater than or equal to 1.1 cm is an indication for reduction. Silber and Flynn,81 in one review of 166 children with pelvic fractures, recommended that all patients with closed triradiate cartilages, regardless of age, be treated as adults with anatomic realignment and stable fixation. Anatomic realignment and fixation is recommended by others for all displaced pelvic ring fractures regardless of age.39,57,69,93 
Preoperative Planning.
Surgery for pelvic ring reduction and fixation in children is rare. Ideally complex surgery is performed by an experienced orthopedic traumatologist, in conjunction with a pediatric orthopedic surgeon, utilizing techniques more commonly needed in adults but modified for children. These modifications include implants sized appropriately for children and techniques that preserve, as much as possible, the potential for growth. Perioperative care is best accomplished with a multidisciplinary team that is familiar with pediatric anesthesia and critical care and includes pediatric trauma nursing, child support services, and pediatric rehabilitation. 
The timing of surgery is based on the needs of the individual patient. Although uncommon, emergency placement of external or internal fixation may be necessary to achieve cardiovascular stability, such as with an open book pelvis fracture not stabilized by a pelvic binder. Complex surgery, however, represents a “second hit” to the traumatized patient that further incites inflammatory processes and challenges the body's ability to respond to the stress of surgery. Although not directly studied in children, the concept of “Damage Control Orthopedics”22 favors delaying surgery until concomitant injuries have been managed and after a period of cardiovascular stability. Because of this, pelvic surgery is typically performed in a delayed fashion, typically 7 to 10 days after the initial injury. 
Many different surgical strategies and techniques may be utilized to achieve reduction and stability. The surgical team must carefully plan which technique or combination of techniques is best for the individual patient. Stabilization of the anterior ring may be accomplished with external fixation, symphyseal, and/or rami plate fixation, or screw fixation of the rami and anterior column (Fig. 25-23). Options for posterior stabilization include sacroiliac screw fixation and plate fixation (Fig. 25-24AE). Because these techniques are discussed in detail in the companion to this text, Rockwood and Green's Fractures in Adults, this section will discuss only the two most commonly utilized techniques for children, external fixation and sacroiliac screw fixation. 
Figure 25-23
This radiographic series highlights treatment of an unstable pelvic fracture with hemodynamic instability.
 
A: Anteroposterior pelvic radiograph of a 12-year-old boy who was a pedestrian hit by a car. There is a wide symphysis and a displaced fracture adjacent to the left sacroiliac joint. The towel clips seen on radiograph are to hold a sheet (sling) around the pelvis to help temporarily control hemorrhage. B: CT scan showing the displaced posterior injury. C: Pelvic radiograph after an anterior external fixation was placed urgently to stabilize the pelvis. This along with resuscitation stabilized the hemodynamic status. D: Once the patient had stabilized, the external fixation was converted to anterior internal fixation with a plate on the symphysis pubis and the posterior instability was treated with a sacroiliac screw.
A: Anteroposterior pelvic radiograph of a 12-year-old boy who was a pedestrian hit by a car. There is a wide symphysis and a displaced fracture adjacent to the left sacroiliac joint. The towel clips seen on radiograph are to hold a sheet (sling) around the pelvis to help temporarily control hemorrhage. B: CT scan showing the displaced posterior injury. C: Pelvic radiograph after an anterior external fixation was placed urgently to stabilize the pelvis. This along with resuscitation stabilized the hemodynamic status. D: Once the patient had stabilized, the external fixation was converted to anterior internal fixation with a plate on the symphysis pubis and the posterior instability was treated with a sacroiliac screw.
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A: Anteroposterior pelvic radiograph of a 12-year-old boy who was a pedestrian hit by a car. There is a wide symphysis and a displaced fracture adjacent to the left sacroiliac joint. The towel clips seen on radiograph are to hold a sheet (sling) around the pelvis to help temporarily control hemorrhage. B: CT scan showing the displaced posterior injury. C: Pelvic radiograph after an anterior external fixation was placed urgently to stabilize the pelvis. This along with resuscitation stabilized the hemodynamic status. D: Once the patient had stabilized, the external fixation was converted to anterior internal fixation with a plate on the symphysis pubis and the posterior instability was treated with a sacroiliac screw.
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Figure 25-23
This radiographic series highlights treatment of an unstable pelvic fracture with hemodynamic instability.
A: Anteroposterior pelvic radiograph of a 12-year-old boy who was a pedestrian hit by a car. There is a wide symphysis and a displaced fracture adjacent to the left sacroiliac joint. The towel clips seen on radiograph are to hold a sheet (sling) around the pelvis to help temporarily control hemorrhage. B: CT scan showing the displaced posterior injury. C: Pelvic radiograph after an anterior external fixation was placed urgently to stabilize the pelvis. This along with resuscitation stabilized the hemodynamic status. D: Once the patient had stabilized, the external fixation was converted to anterior internal fixation with a plate on the symphysis pubis and the posterior instability was treated with a sacroiliac screw.
A: Anteroposterior pelvic radiograph of a 12-year-old boy who was a pedestrian hit by a car. There is a wide symphysis and a displaced fracture adjacent to the left sacroiliac joint. The towel clips seen on radiograph are to hold a sheet (sling) around the pelvis to help temporarily control hemorrhage. B: CT scan showing the displaced posterior injury. C: Pelvic radiograph after an anterior external fixation was placed urgently to stabilize the pelvis. This along with resuscitation stabilized the hemodynamic status. D: Once the patient had stabilized, the external fixation was converted to anterior internal fixation with a plate on the symphysis pubis and the posterior instability was treated with a sacroiliac screw.
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A: Anteroposterior pelvic radiograph of a 12-year-old boy who was a pedestrian hit by a car. There is a wide symphysis and a displaced fracture adjacent to the left sacroiliac joint. The towel clips seen on radiograph are to hold a sheet (sling) around the pelvis to help temporarily control hemorrhage. B: CT scan showing the displaced posterior injury. C: Pelvic radiograph after an anterior external fixation was placed urgently to stabilize the pelvis. This along with resuscitation stabilized the hemodynamic status. D: Once the patient had stabilized, the external fixation was converted to anterior internal fixation with a plate on the symphysis pubis and the posterior instability was treated with a sacroiliac screw.
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Figure 25-24
A 6-year-old boy who was struck by a school bus.
 
He had a pneumothorax and a pelvic fracture. AP pelvis (A) and initial CT scan (B) show an unstable type IV fracture with vertical displacement of the hemipelvis. He was placed in traction during resuscitation (C) with realignment of the fracture. After stabilization 6 days after injury, he underwent closed reduction, SI screw fixation, and application of an external fixator. Post-op radiograph (D) of the pelvis and CT scan (E) show near-anatomic reduction.
He had a pneumothorax and a pelvic fracture. AP pelvis (A) and initial CT scan (B) show an unstable type IV fracture with vertical displacement of the hemipelvis. He was placed in traction during resuscitation (C) with realignment of the fracture. After stabilization 6 days after injury, he underwent closed reduction, SI screw fixation, and application of an external fixator. Post-op radiograph (D) of the pelvis and CT scan (E) show near-anatomic reduction.
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Figure 25-24
A 6-year-old boy who was struck by a school bus.
He had a pneumothorax and a pelvic fracture. AP pelvis (A) and initial CT scan (B) show an unstable type IV fracture with vertical displacement of the hemipelvis. He was placed in traction during resuscitation (C) with realignment of the fracture. After stabilization 6 days after injury, he underwent closed reduction, SI screw fixation, and application of an external fixator. Post-op radiograph (D) of the pelvis and CT scan (E) show near-anatomic reduction.
He had a pneumothorax and a pelvic fracture. AP pelvis (A) and initial CT scan (B) show an unstable type IV fracture with vertical displacement of the hemipelvis. He was placed in traction during resuscitation (C) with realignment of the fracture. After stabilization 6 days after injury, he underwent closed reduction, SI screw fixation, and application of an external fixator. Post-op radiograph (D) of the pelvis and CT scan (E) show near-anatomic reduction.
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External Fixation. External fixation is used to stabilize an unstable fracture with anterior ring separation or anterior fractures. This technique maintains reduction, decreases pain, facilitates mobilization out of bed, and may be better tolerated by older children than spica casting.23,41 External fixation, however, may not effectively control the posterior ring49 for all fracture patterns. Anterior external fixation may be achieved by placing one or two pins in the supra-acetabular bone on each side of the pelvis (Fig. 25-25)72 or by placing one to two pins into each iliac crest and spanning these pin clusters with an external frame, ideally one that allows access to the abdomen. 
Figure 25-25
Fixation of an unstable pelvic fracture with external fixation.
 
One or two pins are placed in the iliac wing. The starting point is 1 to 2 cm posterior to the anterior-superior iliac spine. An anterior-to-posterior supra-acetabular pin may also be used.
One or two pins are placed in the iliac wing. The starting point is 1 to 2 cm posterior to the anterior-superior iliac spine. An anterior-to-posterior supra-acetabular pin may also be used.
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Figure 25-25
Fixation of an unstable pelvic fracture with external fixation.
One or two pins are placed in the iliac wing. The starting point is 1 to 2 cm posterior to the anterior-superior iliac spine. An anterior-to-posterior supra-acetabular pin may also be used.
One or two pins are placed in the iliac wing. The starting point is 1 to 2 cm posterior to the anterior-superior iliac spine. An anterior-to-posterior supra-acetabular pin may also be used.
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Positioning.
The child is typically placed supine on a radiolucent operating room table to allow access for the fluoroscopy unit. Before sterile prepping and draping that extends from just above the umbilicus and includes the anterior pelvis and both lower limbs, the ability to obtain AP, inlet, outlet, and oblique views of the pelvis is confirmed. 
Approach and Technique.
After preparing and draping the patient, manual reduction is attempted, sometimes aided by longitudinal traction applied through an ipsilateral supracondylar femoral traction pin. Once adequate reduction is confirmed by fluoroscopy, external fixation pins are placed through a limited incision at the site of placement. For pins placed into the iliac crest, small transverse stab incisions perpendicular to the crest are made on the ilium approximately 2 cm posterior to the anterior-superior iliac spines. The iliac apophysis is then split at the site of pin placement along the top of the iliac crest. For pins placed above the acetabulum, incisions are made 2 cm superior to the joint and just medial to an imaginary line that extends between the anterior-superior and anterior-inferior iliac spines. Careful muscle splitting is then performed until the periosteum of the anterior supra-acetabular pelvis is visualized. 
For iliac screws, the iliac table may be located by carefully placing a spinal needle or Lenke pedicle probe between the inner and outer tables of the iliac crest. Fluoroscopy is utilized to confirm the location within the iliac crest. The appropriately sized drill is then used to make a tract for the screw. Use of minimal force allows the drill to more easily find its path through the cancellous bone between the dense cortical tables. Once the outer cortex is drilled, the half pin is placed into the ilium. For children, pins measuring 4 to 4.5 mm in diameter are selected and placed by hand with a T-handle driver; 5 mm diameter half-pins are used for adolescents and adults. After placement is confirmed by fluoroscopy, the process is repeated. One to three half-pins are placed in each crest based on the size of the child. Supra-acetabular pins can be placed in an open fashion through anterior incisions utilizing similar techniques. 
The frame is then built by attaching a small rod to each pin cluster. These small rods are then attached to two longer rods that extend medially and obliquely across the midline of the abdomen. These rods are then clamped together anterior to the pelvis with enough space between the frame and the abdomen to allow for swelling and access for examination or potential surgery. The reduction of the pelvic ring is then assessed and the stability of the construct is confirmed by manual stressing under fluoroscopy. 
Postoperative Care.
After frame placement, patients may be out of bed to a chair if pelvic ring stability is acceptable and the associated injuries permit mobilization. Half-pin care is typically initiated within 4 to 7 days of surgery and continues until the frame is removed. Care regimens vary but daily cleaning is typically recommended. By 4 to 6 weeks after placement, limited weight bearing is started. Weight bearing in the frame may be possible for some patients but typically for children is not fully instituted until removal of the frame, which is typically done in the operating room 6 to 10 weeks after application. 
Symphyseal Plating.
Symphyseal plating is a good alternative to anterior ring fixation in some children and adolescents23 This fixation choice is less bulky then external fixation and can often be performed at the time of other procedures for associated urogenital or abdominal injuries The approach and technique are identical to that utilized for adult symphyseal plating, except that the plate size must be selected appropriately based on the size of the child. The best choice is a rigid plate–screw construct, such a 3.5-mm reconstruction plate, but small and less bulky choices may be indicated for smaller patients. 
Sacroiliac Screw Fixation.
Posterior ring injuries in children are typically sacroiliac joint disruptions, either from a true joint disruption or from fractures of the ilium that extend into the SI joint, or sacral fractures. Indications for surgical treatment of these injuries are unstable ring injuries with combined anterior and posterior instability and posterior ring fractures with displacement greater than about 1 cm, although, as noted above, the amount of acceptable displacement is controversial. Closed reduction and percutaneous stabilization is an important strategy for pelvic fracture management in children and is the first option when addressing displaced fractures. Open reduction and plate fixation of posterior ring injuries is indicated when closed reduction and screw fixation techniques cannot achieve adequate realignment or stable fixation. 

Sacroiliac Reduction and Screw Fixation

Preoperative Planning.
Before considering this technique, the CT scan of the pelvis must be carefully scrutinized to determine if the fracture pattern is amenable to closed reduction. Specifically, it is important to determine if comminution or severe displacement may prevent reduction or risk soft tissue or neurovascular entrapment or injury. The CT scan is also necessary to assess the sacral anatomy of the individual patient, which may vary widely, to determine the ideal entry position and safe trajectory. In the pediatric patient, the narrow corridor for safe screw placement makes the procedure difficult.87 When a concomitant anterior pelvic injury is present, it may be necessary to stabilize it prior to fixation of the posterior injury. 
Positioning.
Sacroiliac screw fixation may be performed with the patient supine or prone, determined by the coexisting injuries of the patient. More commonly, the patient is positioned supine on the operating table in such a manner as to permit multiple fluoroscopic views of the pelvis and sacrum including AP, inlet, outlet, and lateral views of the pelvis and sacrum. The patient is prepped and sterilely draped about the entire pelvis extending from the umbilicus to the knee or foot of the limb where displacement is most pronounced. A distal femoral traction pin placed in this limb may be useful to obtain longitudinal traction and influence reduction. 
Technique.
After prepping and draping, the SI joint separation or sacral fracture is manually reduced by applying the appropriate forces—typically compression and longitudinal traction. The reduction is confirmed with AP, inlet, and outlet views. The size of the cannulated screw size should be predetermined based on the CT scan and is typically 7.3 mm for adolescents. In younger children, smaller sizes, such as 6.5 mm and 4.5 mm diameters, can be used. The next step is identifying the starting point for screw entry. Utilizing inlet and outlet pelvic views, the location of the S1 neural foramen is determined and marked to provisionally establish the guide pin entry point. The lateral view is then utilized to identify the optimal location of the starting point in the dorsal/ventral plane. To ensure that a true lateral is obtained, the greater sciatic notches should overlap completely on the image. Based on clinical landmarks, the entry point laterally is typically at the intersection of the long axis of the femur and a vertical line drawn posteriorly from the ASIS. 
Returning to the AP outlet view, the guide pin is then inserted just lateral to the S1 neural foramen and directed toward the safe zone, the area between the alar cortex superoanteriorly and the sacral neural foramen posteriorly. Multiple fluoroscopic views, including the inlet, outlet, and lateral views, are used to confirm guide pin placement. Once the ideal pin placement is achieved, it is advanced just to the midline of the sacrum and the position is reconfirmed with the image intensifier. The guide pin is measured for length and the appropriate cannulated screw is selected. A small incision is then made around the guidewire to allow passage of the cannulated drill, a bone washer if preferred, and the screw without damage to the skin. The screw tract is predrilled and the screw is placed. After fixation, the quality and stability of reduction are assessed (Fig. 25-26). If continued rotational instability is determined, a second may be added. 
Figure 25-26
Placement of a sacroiliac screw.
 
A: Fluoroscopic lateral image of S1 to percutaneously localize the starting point for the guidewire. B: Fluoroscopic 40-degree inlet view showing the direction of the guidewire for anterior and posterior placement in the sacroiliac body. C: Fluoroscopic 40-degree outlet view showing location of the guidewire in relation to the S1 foramen. D: Inlet view after screw placement. E: Outlet view showing screw placement in the body of S1.
A: Fluoroscopic lateral image of S1 to percutaneously localize the starting point for the guidewire. B: Fluoroscopic 40-degree inlet view showing the direction of the guidewire for anterior and posterior placement in the sacroiliac body. C: Fluoroscopic 40-degree outlet view showing location of the guidewire in relation to the S1 foramen. D: Inlet view after screw placement. E: Outlet view showing screw placement in the body of S1.
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A: Fluoroscopic lateral image of S1 to percutaneously localize the starting point for the guidewire. B: Fluoroscopic 40-degree inlet view showing the direction of the guidewire for anterior and posterior placement in the sacroiliac body. C: Fluoroscopic 40-degree outlet view showing location of the guidewire in relation to the S1 foramen. D: Inlet view after screw placement. E: Outlet view showing screw placement in the body of S1.
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Figure 25-26
Placement of a sacroiliac screw.
A: Fluoroscopic lateral image of S1 to percutaneously localize the starting point for the guidewire. B: Fluoroscopic 40-degree inlet view showing the direction of the guidewire for anterior and posterior placement in the sacroiliac body. C: Fluoroscopic 40-degree outlet view showing location of the guidewire in relation to the S1 foramen. D: Inlet view after screw placement. E: Outlet view showing screw placement in the body of S1.
A: Fluoroscopic lateral image of S1 to percutaneously localize the starting point for the guidewire. B: Fluoroscopic 40-degree inlet view showing the direction of the guidewire for anterior and posterior placement in the sacroiliac body. C: Fluoroscopic 40-degree outlet view showing location of the guidewire in relation to the S1 foramen. D: Inlet view after screw placement. E: Outlet view showing screw placement in the body of S1.
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A: Fluoroscopic lateral image of S1 to percutaneously localize the starting point for the guidewire. B: Fluoroscopic 40-degree inlet view showing the direction of the guidewire for anterior and posterior placement in the sacroiliac body. C: Fluoroscopic 40-degree outlet view showing location of the guidewire in relation to the S1 foramen. D: Inlet view after screw placement. E: Outlet view showing screw placement in the body of S1.
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Postoperative Care.
If the pelvic ring is stable after fixation, cast immobilization is not necessary. A spica cast may be necessary for younger children or those with inadequate fixation and ring stability. The patient may be out of bed to a chair after surgery. Weight bearing is restricted for a minimum of 6 weeks before gradual progression. Sacroiliac screws are not typically removed in adults. Although the consequences of SI joint fixation in younger children are not fully understood, it is our preference to remove screws after healing in this younger age group. 

Open Reduction and Plate Fixation

Like adults, open reduction and plating of SI joint disruptions and fractures of the posterior ring are also sometimes indicated, most commonly when adequate reduction cannot be achieved with closed manipulative techniques, such as with large vertical displacement of the hemipelvis. This technique can be done either through an anterior retroperitoneal approach or via a posterior approach. The choice of implants is based on the size of the patient and the fracture type. Safe and effective plate fixation of unstable pelvic injuries has been reported in toddlers utilizing 3.5-mm plating systems and adult techniques.86 

Severe Crush Injuries and Open Fractures

Crush injuries of the pelvis and open fractures are relatively rare. In patients with crushing injuries, distortion of the pelvic ring is severe, resulting in multiple breaks in both the anterior and posterior pelvis as well as the acetabulum and triradiate cartilage. These uncommon injuries are nearly always associated with serious concomitant injuries, particularly thoracoabdominal and genitourinary abnormalities (Fig. 25-27). Neurologic injuries of the lumbosacral plexus and vascular injuries are also common associated findings. Risk of massive hemorrhage is highest for patients who sustain these types of fractures and, in one series, about 20% of children with crushed open pelvic fractures died within hours of admission secondary to uncontrolled hemorrhage.54 Open fractures are more common than crush injuries, representing 13% of patients54 with pelvic fractures, the result of motor vehicle trauma and gunshot wounds. 
Figure 25-27
 
A: Open pelvic fracture with severe displacement. B: The soft tissue injury precluded pelvic reduction and fixation. This radiograph shows remarkable late deformity.
A: Open pelvic fracture with severe displacement. B: The soft tissue injury precluded pelvic reduction and fixation. This radiograph shows remarkable late deformity.
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Figure 25-27
A: Open pelvic fracture with severe displacement. B: The soft tissue injury precluded pelvic reduction and fixation. This radiograph shows remarkable late deformity.
A: Open pelvic fracture with severe displacement. B: The soft tissue injury precluded pelvic reduction and fixation. This radiograph shows remarkable late deformity.
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The principles of emergency management are similar to those applied for other unstable pelvic fractures. Surgical stabilization of the pelvic ring may be extremely challenging in the face of multiple fractures sites, comminution, and soft tissue trauma. Lacerations of the vagina and rectum, bladder injuries, and urethral disruptions complicate management and increase the risk of infection. External fixation alone may not be sufficient to manage these complex injuries, making it frequently necessary to perform internal fixation or a combination of these techniques. Stable pelvic fixation, multiple debridements, soft tissue management, and careful surveillance for infection are recommended to improve the chances of successful outcomes.54 

Treatment Options for Acetabular Fractures

Acetabular fractures constitute only 6% to 17% of pediatric pelvic fractures, making them very uncommon.25,54,81 However, these injuries carry the potential for significant long-term morbidity. The goals of treatment for acetabular fractures in children are twofold. The first is to restore a congruent and stable joint with an anatomically reduced articular surface. The second is to preserve alignment of the triradiate cartilage in hopes of ensuring normal growth. Schlickewei et al.72 noted that there are a variety of injury patterns and limited evidence of outcomes for any specific treatment. Thus, each fracture should be evaluated on an individual basis with the following guidelines: (i) Anatomic reduction will likely result in a good long-term outcome; (ii) MRI is the best tool for identifying closure of the triradiate cartilage; and (iii) patients should be informed about the possibility of growth arrest and secondary associated problems such as joint subluxation or dysplasia.72 

Nonoperative Treatment of Acetabular Fractures

In general, conservative treatment is indicated for simple, nondisplaced fracture patterns. Short-term bed rest followed by non–weight-bearing ambulation with crutches can be used for nondisplaced or minimally (≤2 mm) displaced fractures, particularly those that do not involve the superior acetabular dome. Because weight-bearing forces must not be transmitted across the fracture, crutch ambulation is appropriate only for older children who can reliably avoid weight bearing on the injured limb. Nonweight bearing usually is continued for 6 to 8 weeks. Radiographs should be obtained frequently in the first few weeks to confirm fracture alignment. For those younger children who cannot comply with nonweight bearing ambulation, spica cast immobilization is preferred. 
Skeletal traction is an option for those rare acetabular fractures that can be reduced to ≤2 mm of displacement or those with medical contraindications to surgical treatment. To avoid injury to the physis, the traction pin is usually inserted in the distal femur under anesthesia using fluoroscopic guidance. Follow-up radiographs should confirm fracture reduction and joint congruency, and traction is generally maintained for 4 to 6 weeks until fracture healing is sufficient to allow progressive weight bearing. 
There are few studies reporting the outcome of nonoperative treatment of acetabular fractures in children. Heeg et al.,32 reported on 23 patients with a variety of fracture patterns, with 18 being treated conservatively. The authors reported excellent functional and radiographic results of nonoperative treatment in those who were able to maintain congruent joints. 

Operative Treatment of Acetabular Fractures

Indications/Contraindications

The primary indications for operative treatment of pediatric acetabular fractures are either (1) an unstable joint or (2) an incongruent joint, regardless of fracture pattern. Instability usually results from posterior or anterior wall fractures, and when present must be remedied by operative reduction and fixation. Lack of congruency may result from bony fragments and/or soft tissue within the joint or from fracture displacement in the weight-bearing dome. In the former situation, open reduction is necessary to remove the offending agents and avoid premature osteoarthritis and in the latter case, anatomic restoration of the articular surface with stable internal fixation is the operative goal. Gordon et al.,23 recommended accurate reduction and internal fixation of any displaced acetabular fracture in a child. They noted that the presence of incomplete fractures and plastic deformation may make accurate reduction difficult or impossible; they recommended that incomplete fractures be completed and that osteotomies of the pubis, ilium, or ischium be made if necessary to achieve accurate reduction of the acetabulum.23 Improved outcomes with early (<24 hours) fixation of acetabular fractures in adults have been reported,62 and Gordon et al.23 noted that early fixation (before callus formation) is especially important to prevent malunion in young patients in whom healing is rapid (Fig. 25-28). 
Figure 25-28
 
A: Pelvic radiograph of a 12-year old 1 year after an acetabular fracture. The fracture is a malunion with subluxation of the hip joint. B: Three-dimensional CT scan showing the malunited fragment.
A: Pelvic radiograph of a 12-year old 1 year after an acetabular fracture. The fracture is a malunion with subluxation of the hip joint. B: Three-dimensional CT scan showing the malunited fragment.
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Figure 25-28
A: Pelvic radiograph of a 12-year old 1 year after an acetabular fracture. The fracture is a malunion with subluxation of the hip joint. B: Three-dimensional CT scan showing the malunited fragment.
A: Pelvic radiograph of a 12-year old 1 year after an acetabular fracture. The fracture is a malunion with subluxation of the hip joint. B: Three-dimensional CT scan showing the malunited fragment.
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Another important indication for surgical treatment is malalignment of the triradiate cartilage, which can result in growth arrest and progressive acetabular dysplasia (Fig. 25-29). Linear growth of the acetabulum occurs by interstitial growth in the triradiate part of the cartilage complex, causing the pubis, ischium, and ilium to enlarge. The depth of the acetabulum develops in response to the presence of a spherical femoral head and interstitial growth of the acetabular cartilage.64,75 Growth derangement of all or part of the triradiate cartilage as a result of poor fracture reduction may result in a dysplastic acetabulum. Since the ilioischial limb of the triradiate contributes the most to acetabular growth, injury to the ilioischial limb of the triradiate cartilage has a greater potential for late acetabular deformity than an anterior iliopubic limb injury.21 
Figure 25-29
 
A: CT scan of a 7-year old with a displaced pelvic wing fracture B: CT scan showing the fracture propagation into the triradiate cartilage. C: Anatomic reduction of the triradiate cartilage with open reduction and internal fixation. D: Despite anatomic reduction, medial osseous bar spans the triradiate cartilage at follow-up.
A: CT scan of a 7-year old with a displaced pelvic wing fracture B: CT scan showing the fracture propagation into the triradiate cartilage. C: Anatomic reduction of the triradiate cartilage with open reduction and internal fixation. D: Despite anatomic reduction, medial osseous bar spans the triradiate cartilage at follow-up.
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Figure 25-29
A: CT scan of a 7-year old with a displaced pelvic wing fracture B: CT scan showing the fracture propagation into the triradiate cartilage. C: Anatomic reduction of the triradiate cartilage with open reduction and internal fixation. D: Despite anatomic reduction, medial osseous bar spans the triradiate cartilage at follow-up.
A: CT scan of a 7-year old with a displaced pelvic wing fracture B: CT scan showing the fracture propagation into the triradiate cartilage. C: Anatomic reduction of the triradiate cartilage with open reduction and internal fixation. D: Despite anatomic reduction, medial osseous bar spans the triradiate cartilage at follow-up.
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Preoperative planning checklist would include: 
  •  
    C-arm
  •  
    Fluoroscopic table such as a Jackson table
  •  
    Screw set including long 3.5 to 4.5 mm and various sized cannulated screws
  •  
    Threaded Kirschner wires
  •  
    Plate set including small fragment plates, pelvic reconstruction plates, and smaller “hook” plates
  •  
    Pelvic retractors, clamps, and reduction instruments
  •  
    Femoral distractor
  •  
    Positioning and surgical approach
The positioning and approach for ORIF of pediatric acetabular fractures varies according to the pattern of the fracture and the direction of the displacement as determined on the preoperative radiographs and CT scans (Table 25-5).23 Fractures of the posterior wall and/or posterior column can be approached through a Kocher–Langenbeck approach with the patient either in the lateral decubitus or prone position (Fig. 25-30). Anterior column injuries can be approached through an ilioinguinal approach with the patient placed supine. Some transverse fractures may require an extended iliofemoral approach.1 The extended lateral approaches, which include the extended iliofemoral and triradiate approaches, should be avoided as much as possible because of the risk of devascularization of the ilium and heterotopic bone formation.28 
Table 25-5
Surgical Exposure for Operative Fixation of Acetabular Fractures
Fracture Type Exposure
Anterior column or wall Ilioinguinal
Posterior column or wall Kocher–Langenbeck
Transverse Ilioinguinal (or extended lateral)
T-shaped Ilioinguinal and Kocher–Langenbeck (or extended lateral)
Anterior column and posterior hemitransverse Ilioinguinal
Both columns Ilioinguinal (or extended lateral)
 

From Gordon RG, Karpik K, Hardy S. Techniques of operative reduction and fixation of pediatric and adolescent pelvic fractures. Oper Tech Orthop. 1995; 5:95–114, with permission.

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Figure 25-30
 
A: Radiograph of a football injury with posterior acetabular fracture and dislocation. B, C: Postoperative radiographs after a posterior approach and plating.
A: Radiograph of a football injury with posterior acetabular fracture and dislocation. B, C: Postoperative radiographs after a posterior approach and plating.
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Figure 25-30
A: Radiograph of a football injury with posterior acetabular fracture and dislocation. B, C: Postoperative radiographs after a posterior approach and plating.
A: Radiograph of a football injury with posterior acetabular fracture and dislocation. B, C: Postoperative radiographs after a posterior approach and plating.
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Technique

The operative treatment of pediatric/adolescent acetabular fractures is technically demanding and is best performed by experienced surgeons. Given the rarity of these injuries in children, it may be helpful to consult and/or collaborate with an adult orthopedic traumatologist.58 The operative surgeon should be familiar with the treatise by Judet et al.37 on the operative reduction of acetabular fractures and with Letournel and Judet's44 work before performing this surgery. For smaller children and smaller fragments, Watts98 recommended threaded Kirschner wires for fixation. In larger children, cannulated screws can provide secure fixation (Figs. 25-31 and 25-32). Small-fragment reconstruction plates, appropriately contoured, also can be used. Gordon et al.23 described the addition of a small (two- or three-hole) “hook plate” for small or comminuted fragments (Fig. 25-33). 
Figure 25-31
 
A: Fracture of the wing of the ilium with extension into the dome of the acetabulum in a 3-year-old boy. B: After reduction and fixation with two cannulated screws.
 
(From Habacker TA, Heinrich SD, Dehne R. Fracture of the superior pelvic quadrant in a child. J Pediatr Orthop. 1995; 15(1):69–72, with permission.)
A: Fracture of the wing of the ilium with extension into the dome of the acetabulum in a 3-year-old boy. B: After reduction and fixation with two cannulated screws.
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Figure 25-31
A: Fracture of the wing of the ilium with extension into the dome of the acetabulum in a 3-year-old boy. B: After reduction and fixation with two cannulated screws.
(From Habacker TA, Heinrich SD, Dehne R. Fracture of the superior pelvic quadrant in a child. J Pediatr Orthop. 1995; 15(1):69–72, with permission.)
A: Fracture of the wing of the ilium with extension into the dome of the acetabulum in a 3-year-old boy. B: After reduction and fixation with two cannulated screws.
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Figure 25-32
 
A: Radiograph of a 13-year old with an acetabular fracture though the closing triradiate cartilage. B: CT scan showing the fracture in the region of the triradiate and posterior wall. C: Postoperative radiograph of the fracture fixed with cannulated screws via a surgical hip dislocation approach.
A: Radiograph of a 13-year old with an acetabular fracture though the closing triradiate cartilage. B: CT scan showing the fracture in the region of the triradiate and posterior wall. C: Postoperative radiograph of the fracture fixed with cannulated screws via a surgical hip dislocation approach.
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Figure 25-32
A: Radiograph of a 13-year old with an acetabular fracture though the closing triradiate cartilage. B: CT scan showing the fracture in the region of the triradiate and posterior wall. C: Postoperative radiograph of the fracture fixed with cannulated screws via a surgical hip dislocation approach.
A: Radiograph of a 13-year old with an acetabular fracture though the closing triradiate cartilage. B: CT scan showing the fracture in the region of the triradiate and posterior wall. C: Postoperative radiograph of the fracture fixed with cannulated screws via a surgical hip dislocation approach.
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Figure 25-33
 
A: Anterior column plate and additional wall “hook” plate. B: Posterior wall buttress plate and hook plate.
 
(From Gordon RG, Karpik K, Hardy S. Techniques of operative reduction and fixation of pediatric and adolescent pelvic fractures. Oper Tech Orthop. 1995; 5:95–114, with permission.)
A: Anterior column plate and additional wall “hook” plate. B: Posterior wall buttress plate and hook plate.
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Figure 25-33
A: Anterior column plate and additional wall “hook” plate. B: Posterior wall buttress plate and hook plate.
(From Gordon RG, Karpik K, Hardy S. Techniques of operative reduction and fixation of pediatric and adolescent pelvic fractures. Oper Tech Orthop. 1995; 5:95–114, with permission.)
A: Anterior column plate and additional wall “hook” plate. B: Posterior wall buttress plate and hook plate.
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Brown et al.5 described the use of CT image-guided fixation of acetabular fractures in 10 patients, including bilateral posterior wall fractures in a 14-year-old girl. They cite as advantages of image-guided surgery reduced operating time (∼20% reduction), less extensive surgical dissection, reduced fluoroscopic time, and compatibility with traditional fixation techniques. Most important, it allows accurate and safe placement of screws and pins for acetabular fixation. This technology is attractive, but anatomic reduction of the joint surface and secure fixation outweigh the benefits of surgical convenience. 

Postoperative Care

Small children can be immobilized in a spica cast for 6 weeks after surgery. If radiographs show adequate healing at that time, the cast is removed and free mobility is allowed. In an older child with stable fixation, crutches are used for protected weight bearing for 6 to 8 weeks. If radiographs show satisfactory healing, weight bearing is progressed as tolerated. Return to vigorous activities, especially competitive sports is delayed for at least 3 months. For most children, metallic implants should be removed 6 to 18 months after surgery, assuming adequate healing, to facilitate future imaging and operative procedures about the hip. 
Pelvic radiographs should be obtained for 2 years after an acetabular fracture looking for a triradiate closure. If the radiographs indicate a physeal bar, CT and MRI can be obtained to confirm the diagnosis. 

Potential Pitfalls and Preventive Measures

The potential complications following treatment of an acetabular fracture include avascular necrosis, posttraumatic arthritis, premature closure of the triradiate cartilage, infection, iatrogenic nerve injury, heterotopic ossification, fracture malunion, intra-articular penetration of implants, and venous thromboembolism. Although some of these outcomes may be unavoidable as a result of the initial injury, many can be prevented or at least mitigated by accurate decision making, detailed surgical technique, and appropriate perioperative care (Table 25-6). 
Table 25-6
Pitfalls of Acetabular Fracture Surgery and Suggestions for Prevention
Pitfalls or Complications Strategies for Prevention or Treatment
Avascular necrosis of the femoral head Urgent treatment of fracture-dislocations of the hip
Posttraumatic arthrosis Anatomic or near-anatomic (≤2 mm) reduction of the articular surface
Iatrogenic sciatic nerve injury (posterior approach) Consider intraoperative nerve monitoring; careful patient positioning; maintain knee flexion during posterior approach
Iatrogenic LFCN injury (anterior approach) Careful retraction of LFCN; inform patient about potential for postoperative symptoms
Heterotopic ossification Minimize stripping of gluteal muscles from outer table of ilium; careful choice of surgical approach; consider prophylaxis with indomethacin
Fracture malunion Timely and accurate reduction and fixation of fractures
Intra-articular placement of implants Use of intraoperative fluoroscopy supplemented by intraoperative portable radiographs when necessary. Consider postoperative CT scan to confirm appropriate implant position.
Venous thromboembolism Early mobilization; mechanical prophylaxis (e.g., compression boots, foot pumps); consider chemoprophylaxis
 

LFCN, lateral femoral cutaneous nerve.

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Author's Preferred Treatment of Pelvic and Acetabular Fractures

We almost always manage low energy pelvic avulsion fractures (Torode and Zieg Type I) conservatively with rest and partial weight bearing on crutches for 2 or more weeks, followed by gradual resumption of normal activities after about 6 weeks. For those rare fractures with significant displacement (>2 cm) or persistent disability, fragment fixation, or excision may be warranted. 
For higher-energy pelvic and acetabular fractures, a multispecialty approach is essential, especially at the time of initial presentation. The team should be aware of the large incidence of concomitant injuries to the head, thorax, and abdomen. The urogenital system should be carefully evaluated specifically looking for open fractures. If there is hemodynamic instability, the trauma surgeon, orthopedic surgeon, radiologist, and blood bank should work together to stabilize the patient. The orthopedic surgeon can provide temporary relief with pelvic wrapping, external fixation, or wound packing depending on the treatment of other injuries. If needed, operative fixation can be done in the same session as surgery for associated injuries or it can be timed later when the patient is stabilized. 
Definitive treatment is usually conservative for isolated iliac wing fractures (Torode and Zieg Type II), and simple pubis and ischium fractures (Torode and Zieg Type III), and consists of symptomatic treatment and protected weight bearing. For toddlers and younger school-age children, this treatment may include a spica cast for immobilization and comfort. For more involved pelvic and acetabular fractures, treatment is more likely to be conservative in children with an immature pelvis and operative in children with an unstable fracture pattern and a mature pelvis or closed triradiate cartilage.81 In the younger, immature child with severe displacement, femoral traction on the displaced side of the hemipelvis may be indicated if operative reduction with implants is not technically feasible. There is mounting evidence, however, that unstable pelvic fractures and displaced acetabular fractures in children should be operatively reduced and stabilized using the same principles as in adults. Given the technically demanding nature of these operations, it is important that the surgeon has experience with these procedures and, if necessary, we recommend consultation and collaboration with an adult orthopedic traumatologist. 
Torode and Zieg class IV injuries with displacement and/or pelvic ring fractures with displacement of more than 1 cm and anterior and posterior ring fractures should undergo reduction and fixation. Open reduction of the sacroiliac joint or a posterior iliac injury can be performed with a combination of plate and/or screws. The approach can be anterior in the iliac fossa or posterior depending on the fracture characteristics. Sacroiliac screws can be used in the immature pelvis, but the anatomy and size of S1 must be conducive for screw placement. Imaging, including the use of fluoroscopy for placement of the screws, is necessary. With a widened symphysis, anterior external fixation or plating is recommended along with posterior stabilization. Similarly, we advocate open reduction and internal fixation for any pediatric acetabular fracture that is associated with hip instability, incongruity of the joint, or significant displacement of the triradiate cartilage. The surgical approach and technique for fixation is dictated by the fracture pattern. 

Complications and Adverse Outcomes Related to Pelvic and Acetabular Fractures

The major adverse outcomes following treatment of pediatric pelvic and acetabular fractures are malunion of the pelvic ring leading to long-term morbidity and premature triradiate closure after acetabular fracture. Because of the rapid healing in young children, loss of reduction and nonunion usually are not problems. Malunion of the pelvis can lead to leg-length discrepancy, sacroiliac joint arthrosis, back pain, lumbar scoliosis, incompetency of the pelvic floor, and distortion of the birth canal. Because of the possibility of dystocia during childbirth, pelvimetry is recommended before pregnancy. Rieger and Brug69 reported one female patient who Required Caesarean section because of ossification of the symphysis pubis after nonoperative treatment of an open-book fracture. Schwarz et al.74 reported leg-length discrepancies of 1 to 5 cm in 10 of 17 patients after nonoperative treatment of unstable pelvic fractures; 5 had low back pain at long-term follow-up. McDonald50 reported that one-third of 15 skeletally immature patients treated nonoperatively with unstable pelvic fractures had residual pain. Heeg and Klassen31 reviewed 18 children with unstable pelvic fractures and reported that 9 had a leg-length discrepancy greater than 1 cm and 3 had back pain. For those patients with growth remaining, an appropriately timed epiphysiodesis may be used to manage any residual leg length discrepancy. Of course the best way to avoid the negative effects of pelvic malunion is to achieve and maintain an adequate initial reduction. 
Acetabular dysplasia secondary to growth arrest of the triradiate cartilage is a concerning complication after trauma to the acetabulum. Premature closure of the triradiate cartilage has an overall incidence of less than 5% (range 0% to 11%) after pediatric acetabular fractures.32,45,75,95 Heeg33 reported acetabular deformity and subluxation of the hip in two of three patients with premature fusion of the triradiate cartilage. Peterson and Robertson61 reported formation of a physeal osseous bar in a 7-year-old boy 2 years after fracture of the lateral portion of the superior ramus at the junction with the triradiate cartilage. After excision of the osseous bridge, the physis remained open. Although the injured physis closed earlier than the contralateral side, there was only a slight increase in the thickness of the acetabular wall and lateral displacement of the femoral head. The authors emphasized that early recognition and treatment are essential before premature closure of the entire physis and development of permanent osseous deformity (Fig. 25-34).61 
Figure 25-34
 
A: Radiograph of a 2-year old with a ramus fracture that involves the triradiate cartilage. B: Six months after the injury, there is indication of a physeal bar on the medial aspect of the triradiate cartilage. C: MRI confirming the presence of a physeal bar. D: CT scan confirming the physeal bar. E: CT scan confirming the physeal bar excision. This procedure was performed through an ilioinguinal approach and CT-guided excision. F: Radiograph of the pelvis after bar excision.
A: Radiograph of a 2-year old with a ramus fracture that involves the triradiate cartilage. B: Six months after the injury, there is indication of a physeal bar on the medial aspect of the triradiate cartilage. C: MRI confirming the presence of a physeal bar. D: CT scan confirming the physeal bar. E: CT scan confirming the physeal bar excision. This procedure was performed through an ilioinguinal approach and CT-guided excision. F: Radiograph of the pelvis after bar excision.
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A: Radiograph of a 2-year old with a ramus fracture that involves the triradiate cartilage. B: Six months after the injury, there is indication of a physeal bar on the medial aspect of the triradiate cartilage. C: MRI confirming the presence of a physeal bar. D: CT scan confirming the physeal bar. E: CT scan confirming the physeal bar excision. This procedure was performed through an ilioinguinal approach and CT-guided excision. F: Radiograph of the pelvis after bar excision.
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Figure 25-34
A: Radiograph of a 2-year old with a ramus fracture that involves the triradiate cartilage. B: Six months after the injury, there is indication of a physeal bar on the medial aspect of the triradiate cartilage. C: MRI confirming the presence of a physeal bar. D: CT scan confirming the physeal bar. E: CT scan confirming the physeal bar excision. This procedure was performed through an ilioinguinal approach and CT-guided excision. F: Radiograph of the pelvis after bar excision.
A: Radiograph of a 2-year old with a ramus fracture that involves the triradiate cartilage. B: Six months after the injury, there is indication of a physeal bar on the medial aspect of the triradiate cartilage. C: MRI confirming the presence of a physeal bar. D: CT scan confirming the physeal bar. E: CT scan confirming the physeal bar excision. This procedure was performed through an ilioinguinal approach and CT-guided excision. F: Radiograph of the pelvis after bar excision.
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A: Radiograph of a 2-year old with a ramus fracture that involves the triradiate cartilage. B: Six months after the injury, there is indication of a physeal bar on the medial aspect of the triradiate cartilage. C: MRI confirming the presence of a physeal bar. D: CT scan confirming the physeal bar. E: CT scan confirming the physeal bar excision. This procedure was performed through an ilioinguinal approach and CT-guided excision. F: Radiograph of the pelvis after bar excision.
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Bucholz et al.6 noted two main patterns of physeal injury in nine patients with triradiate cartilage injury: A Salter–Harris type I or II injury, which had a favorable prognosis for continued normal acetabular growth, and a crush injury (Salter–Harris V), which had a poor prognosis with premature closure of the triradiate cartilage caused by formation of a medial osseous bridge. In either pattern, the prognosis depended on the child's age at the time of injury. In young children, especially those younger than 10 years of age, acetabular growth abnormality was common and resulted in a dysplastic acetabulum. By the time of skeletal maturity, disparate growth increased the incongruity of the hip joint and led to progressive subluxation. Triradiate injuries that occurred after the age of 10, however, generally did not result in significant changes to the acetabulum because of the diminished growth remaining in these patients. As a result, excision of a physeal bar is generally recommended for patients younger than 10 years of age. 
The typical dysplastic changes seen after premature closure of the triradiate cartilage differ significantly from developmental dysplasia and include both lateralization of the hip joint and acetabular retroversion.16,95 In severe cases, subluxation or dislocation can develop. Once present, this posttraumatic dysplasia often requires a complete redirectional acetabular osteotomy to improve femoral head coverage and correct the malorientation of the acetabulum.6,95 

Summary, Controversies, and Future Directions Related to Pelvic and Acetabular Fractures

Pelvic fractures are less common in the pediatric population, with only a small percentage of patients requiring operative treatment. In children, the overall long-term prognosis is generally more favorable than in adults. Many children, however, have serious associated injuries including head trauma, and thoracoabdominal and genitourinary injuries that contribute to the morbidity for these patients. Massive hemorrhage and death are rarely caused by the pelvic fracture itself and more commonly result from the concomitant injuries associated with unstable fracture patterns, particularly those with vertical displacement of the hemipelvis and double breaks in the pelvic ring (modified Torode and Zeig types IIIb and IV). The goals of emergency treatment are to stabilize the hemodynamic status of the patient and to diagnose and treat serious, life-threatening associated injuries. Unstable pelvic fractures may initially require stabilization with a pelvic binder or external fixator. For most patients with displaced pelvic ring fractures, fracture realignment and stable fixation is utilized to reduce the risk of long-term complications such as leg-length discrepancy, back pain, and sacroiliac joint arthrosis. 
The future of pelvic fracture management has to address several important topics. Although much progress has been made regarding the delivery of specialized pediatric trauma care, the development of techniques and the knowledge gained from research at these specialized centers must continually be updated and disseminated to all who provide emergency trauma care for children. This is particularly important with regard to management of unstable pediatric pelvic fractures. Because of their rarity, few surgeons gain a broad experience managing these injuries at children's hospitals where most of these injuries initially present. Collaboration with adult orthopedic traumatologists is, in our opinion, the solution to this problem. Together, principles of treatment and protocols for care can be refined including emergency management strategies, such as the use of embolization for massive bleeding, and the best indications for surgery that are specific for pediatric patients. 
From the standpoint of surgical techniques, pelvic fracture management must continue to improve so that procedures that are routinely performed on adults may be safely applied to children. Advances in implant development and the increased availability of intraoperative navigation may improve the outcomes of pelvic fracture surgery for children of all ages with severe injuries. With advances in the care of the pediatric polytrauma patient and technical improvements for pelvic fracture management, the hope is that mortality will be greatly reduced and that the long-term complications may be eliminated or at least made more manageable for patients as they progress into adulthood. 

References

1.
Crenshaw AH Jr. Extensile acetabular approaches. In: Canale ST, ed. Campbell's Operative Orthopaedics. Vol. 1. 10th ed. St. Louis, MO: Mosby; 2003.
2.
Blasier RD, McAtee J, White R, et al. Disruption of the pelvic ring in pediatric patients. Clin Orthop Relat Res. 2000;(376):87–95.
3.
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