Study Guide

Pelvic Fractures

Key Points:

Description:

Pediatric pelvic fractures are uncommon injuries that are typically associated with high-energy trauma. Patients with pelvic ring injuries require a thorough trauma evaluation given the potential for concomitant injuries of the brain, abdominal viscera and genitourinary system. Avulsion injuries are a subset of pediatric pelvic fractures that occur in the adolescent population and are sustained by lower energy mechanisms. The unique anatomy of the immature pelvis predisposes to injury patterns, treatment options, and outcomes that significantly differ from adults.
 
The pediatric pelvis is more elastic than the adult pelvis due to increased cartilage and thickened periosteum. The sacroiliac and pubic symphyseal joints are wider and thicker in children than adults and are capable of absorbing a greater amount of force. Therefore, a higher energy mechanism is required to cause a fracture compared with the adult population. The thickened periosteum prevents bony displacement of the pelvic ring, but significant soft tissue injury often results from the absorbed forces. The intrapelvic viscera are not well protected and often sustain injury in the absence of pelvic fractures.(Gansslen, 2013) When a fracture does occur, there are a disproportionate number of single pelvic bone injuries due to the elastic biomechanical properties of the immature pelvis. (Gansslen, 2013; Holden, 2007) Single bone fractures of the pelvis are associated with lower incidence of vascular disruption and hemorrhage. Additionally, pediatric smaller-diameter vessels undergo vasoconstriction more readily than the larger, more friable adult vessels, resulting in an overall lower rate of morbidity and mortality secondary to pelvic hemorrhage. (Holden, 2007)
 
The epiphyseal and apophyseal regions of the growing pelvis also predispose children to unique injuries and sequelae. The apophyses are most commonly associated with avulsion injuries and are located on the ischial tuberosity, the anterior inferior iliac spine, and the anterior iliac crest. Avulsion injuries occur during sports activities from a disruption of the tendon origin on the bone. Fractures through the epiphyseal and apophyseal growth centers may result in growth arrest, leg length discrepancy, and deformity. (Gansslen, 2013; Holden, 2007; Amorosa, 2014; Sink 2014)
 
The mechanism of injury is also a key distinction between adult and pediatric pelvic fractures. The majority of pediatric pelvic fractures are sustained during motor vehicle accidents and are the result of pedestrians struck by motor vehicles. Pedestrians are more likely to be struck on the side of the body, causing a lateral compression injury. In contrast, adults and adolescents who are drivers or front-seat passengers are susceptible to anterior-posterior pelvic injuries, while children passengers are more likely to sustain lateral compression injuries.  These differences in injury patterns may also be a factor as to why mortality rates are lower in children with pelvic injuries. (Holden, 2007; Demetriades, 2003)
 
Several classification systems have been proposed in an effort to guide treatment of pelvic injuries in the pediatric population. (Watts, 1976; Tile, 1996; Torode, 1985) The key factors for decision-making include the skeletal maturity of the pelvis and the stability of the injury. Fracture patterns vary significantly by maturity. The triradiate cartilage of the acetabulum closes at approximately 12 years of age in girls and 14 years of age in boys and marks the time at which the pelvic bones become stronger than the pelvic ligaments. An immature pelvis with open triradiate cartilage most commonly sustains fractures of the pubic rami and iliac wings. Adolescents with a closed triradiate cartilage most commonly sustain fractures of the acetabulum, diastasis of the pubic symphysis, and separation of the sacroiliac joints. (Amorosa, 2014)
 
Although no ideal classification system exists for pediatric pelvic injuries, the two most commonly used systems include the Tile classification (Table 1) and the Torode and Zieg classification (Table 2). The Tile classification is commonly used for the adult population and separates injury patterns based upon the stability of the pelvic ring. Type A are stable injuries and include avulsion fractures and non-displaced ring injuries. Type B are rotationally unstable, but vertically stable and include lateral compression with fractures of the pubic and ischial rami, as well as anterior compression fractures with pubic diastasis. Type C fractures are both rotationally and vertically unstable. These injuries include bilateral pubic rami fractures (straddle injuries), vertical shear fractures, and acetabular fractures. The classification system of Torode and Zieg is most commonly cited, however, it is also limited in its ability to account for the changing maturity of the pediatric pelvis. (Torode, 1985) Type I fractures are low-energy avulsion fractures. Type II injuries are iliac wing fractures, typically caused by a laterally directed force. Type III fractures are simple ring fractures involving pubic rami or disruption of the pubic symphysis. Type IV fractures are more serious injuries with ring disruption and include straddle injuries, sacroiliac joint disruption, and combined pelvic ring and acetabular fractures.

Epidemiology:

Pelvic fractures are relatively rare in children, accounting for an estimated 0.3-4% of pediatric injuries. (Gansslen, 2013; Holden, 2007; Manerjee, 2009; Silber, 2001) There is an overall male predominance with a male: female ratio of approximately 1.4:1. (Gansslen, 2013; Holden, 2007) Approximately 20% of pediatric polytrauma victims have pelvic ring injuries and 58-87% of children with pelvic fractures have associated injuries. (Sink, 2014) An estimated 10% of immature pelvic fractures are unstable and 18% are complex. (Smith, 2005) Mortality rates are cited and death most commonly due to head injury, rarely due to exsanguination.

Clinical Findings:

A full trauma evaluation following the advanced pediatric life support protocol (APLS) must be initiated in any pediatric patient suspected to have sustained a pelvic ring injury. Assessment begins with airway, breathing, circulation, and exposure and is followed by complete primary and secondary surveys.
 
Initial inspection should focus on pelvic asymmetry, leg length discrepancies, and the soft tissues of the pelvis and perineum. Complete evaluation of the vagina, scrotum and urethra is necessary to rule out urethral injury and open fractures. (Junkins, 2001) If urethral injury is suspected, a retrograde urethrogram must be performed before catheterization for urine output monitoring. Lacerations in the perineal region and significant ecchymosis over the pelvis should raise suspicion for a pelvic injury. Morel-Lavallee lesions are internal degloving injuries involving a shearing of the subcutaneous fat and skin off the underlying fascia.
 
The pelvis should be palpated for tenderness and crepitus over the anterior superior iliac spines, iliac crests, sacroiliac joints, and pubic symphysis. Rectal exam is indicated to detect tears, open fractures with palpable bone fragments, and prostate injuries. The degree of pelvic stability is determined by placing anterior-posterior and lateral compression forces on the iliac wings. Repeated maneuvers must be avoided to reduce the risk of bleeding by disrupting any clot that may have formed. If the pelvis is determined to be unstable, a pelvic binder or sheet should be placed to decrease intra-pelvic volume and tamponade bleeding. (Amorosa, 2014) A thorough neurovascular exam of the bilateral lower extremities must be performed and documented.

Imaging Studies:

The AP pelvis radiograph is the gold standard for evaluation of pelvic injury and should be performed during assessment of all pediatric polytrauma. Identification of pelvic fractures on the initial AP pelvis radiograph should raise suspicion for associated injuries. Patients transferred from outlying facilities to a pediatric trauma center may have limited quality images or positioning that is not ideal.  Careful review of the images is required, especially in the skeletally immature patient.  Images should be carefully scrutinized for potential injury to the  triradiate cartilage.  Once the child is stabilized additional radiographic views should be obtained to further evaluate the various injury patterns. Inlet (60° caudal) and outlet (45° cranial) radiographs are performed to evaluate the pelvic ring and sacroiliac joints. Judet views (45° oblique) assist in visualizing acetabular injuries.
 
Computed tomography (CT) of the abdomen and pelvis is performed in all hemodynamically unstable polytraumatized patients. CT provides the most effective method of visualizing bony pelvic injuries and has significant utility for preoperative planning.  
 
Magnetic resonance imaging (MRI) is indicated in very young patients with high suspicion for pelvic injury and no clear fracture identified on radiographs. (Amorosa, 2014) MRI is most sensitive for evaluating non-ossified portions of pelvic ring and acetabulum. Apophyseal avulsion injuries may also be identified with MRI of the pelvis.

Treatment:

Numerous factors guide the treatment of pediatric pelvic fractures, including skeletal maturity, fracture pattern, pelvic stability, and hemodynamic status. The majority of pediatric pelvic fractures are treated non-operatively and heal without complications. (Holden, 2007) Treatment of the associated life-threatening injuries is paramount in the case of the polytraumatized pediatric patient.
 
Emergent treatment
Initial management of hemodynamic instability and damage-control orthopaedics is critical.  Pelvic angiography and embolization therapy may have a role for displaced pelvic ring injuries and hemodynamic instability when the bleeding is not controlled by stabilizing the pelvis.  There is scant discussion of this in the literature but studies suggest that embolization may be required in less than 3% of cases of pelvic fracture. (Holden, 2007)  Emergent provisional pelvic ring stability may be achieved with a pelvic sheet, binder, or external fixation.
 
Definitive Treatment
Non-operative treatment includes protected weight bearing followed by physical therapy. Indications include Type I avulsion injuries with < 2 cm displacement and Type II iliac wing fractures with < 2 cm displacement. Treatment of these injuries include protected weight bearing for 2-4 weeks, followed by physical therapy and resumption of normal activities within 6-8 weeks post-injury. (Holden, 2007) Type III fractures of the pelvic ring are stable injuries and may also be treated conservatively. Children with Type III injuries without extension into the acetabulum may be weight bearing as tolerated for 6 weeks. Type III injuries with extension of a non-displaced fracture into the acetabulum are also considered stable fractures that can be treated initially with no weight bearing and then progression to weight bearing as tolerated. Very young patients with stable fractures with acetabular extension may be treated with spica cast immobilization. Type III pelvic ring injuries with a displaced acetabular component may also initially be treated non-operatively with distal femoral traction to improve alignment.
 
Operative intervention is indicated for significantly displaced fractures of the pelvic ring. Delayed open reduction and internal fixation with anterior pubic symphysis plating and percutaneous sacroiliac screw fixation may be required. Additional indications for open reduction and internal fixation include Type I-III fractures with > 2-3 cm of fracture displacement. Available evidence within the literature suggests that unstable and displaced pediatric pelvic fractures are associated with poor functional and clinical outcomes if treated non-operatively. (Amorosa, 2014)

Complications:

Acute complications of pelvic trauma include hemorrhage, neurovascular injury, and even death. However, these complications are more commonly attributed to associated injuries of the brain and intra-abdominal organs, rather than the bony pelvic injuries.

Long-term complications are also relatively uncommon and most pediatric pelvic injuries heal well without persistent deleterious effects. Nonunions are rare and malunion is well tolerated due to the remodeling potential of the immature pelvis. Failure to treat fractures with > 2 cm vertical displacement of the hemipelvis may result in leg length discrepancy, gait disturbance, and persistent low back pain. All acetabular injuries are at risk for developing post-traumatic arthritis regardless of degree of displacement. Fractures through the physeal regions of the pelvis and acetabulum may lead to premature fusion and resultant growth disturbance. There is an inverse relationship between age at time of injury and severity of growth disturbance. Therefore, it is essential to identify these physeal injuries early and follow the patient to skeletal maturity.

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References:

  1. Amorosa LF, Kloen P, Helfet DL. High-energy pediatric pelvic and acetabular fractures. Orthop Clin N Am. 2014;45:483-500.
  2. Demetriades D, Karaiskakis M, Velmahos GC, Alo K, Murray J, Chan L. Pelvic fractures in pediatric and adult trauma patients: are they different injuries? J Trauma. 2003;54:1146-1151.
  3. Gansslen A, Heidari N, Weinberg, AM. Fractures of the pelvis in children: a review of the literature. Eur J Orthop Surg Traumatol. 2013;23:847-861.
  4. Holden CP, Holman J, Herman MJ. Pediatric pelvic fractures. J Am Acad Orthop Surg. 2007;15:172-177.
  5. Junkins EP, Nelson DS, Carroll KL, Hansen K, Furnival RA. A prospective evaluation of the clinical presentation of pediatric pelvic fractures. J Trauma. 2001;51:64-68.
  6. Manerjee S, Marry MJ, Paterson JM. Paediatric pelvic fractures: 10 years experience in a trauma centre. Injury. 2009;40:410-413.
  7. Silber JS, Flynn JM, Koffler KM, Dormans JP, Drummond DS. Analysis of the cause, classification, and associated injuries of 166 consecutive pediatric pelvic fractures. J Pediatr Orthop. 2001;21:446-450.
  8. Sink EL, Flynn JM. Thoracolumbar spine and lower extremity fractures. In: Weinstein, SL, Flynn JM, Lovell and Winter’s Pediatric Orthopaedics. 7th ed. Philadelphia: Lippincott Williams & Wilkins; 2014:1776-1778.
  9. Smith W, Shurnas P, Morgan S, Agudelo J, Luszko G, Knox EC, Georgopoulos G. Clinical outcomes of unstable pelvic fractures in skeletally immature patients. J Bone Joint Surg Am. 2005; 87:2423-2431.
  10. Tile M. Acute pelvic fractures: I. Causation and classification. J Am Acad Orthop Surg. 1996;4(3):143-51.
  11. Torode I, Zieg D. Pelvic fractures in children. J Pediatr Orthop.1985;5:76-84.
  12. Watts HG. Fracture of the pelvis in children. Orthop Clin North Am. 1976:7:615-624.

Top Contributors:

Stephanie J. Swensen, MD
Norman Y. Otsuka, MD