Rockwood & Wilkins’ Fractures in Children
6th Edition

Chapter 20
Fractures of the Pelvis
Roger F. Widmann
Pelvic fractures comprise less than 0.2% of all pediatric fractures (1,2), but pelvic fractures constitute between 1% and 5% of admissions to level 1 pediatric trauma centers (3,4,5,6,7). The most important aspect of treatment of these fractures is the appreciation of the high-energy mechanism of injury and the associated injuries to other systems including the neurovascular structures, abdominal viscera, genitourinary system, musculoskeletal system, and central nervous system. Injuries to the pelvis and spine are associated with the longest hospital stays and the most admissions to the intensive care unit, and the highest rates of mortality in patients with multiple injuries (8,9). When a pelvic fracture is identified in a child, it is an indication that the child may have other significant life-threatening injuries to soft-tissues including but not limited to the abdominal and genitourinary system. The mortality rate in children with pelvic fractures was between 2.4% and 14.8% in recent large series from level 1 pediatric trauma centers (3,4,5,6,7,10,11,12,13,14,15,16). Central nervous system head injury was cited as the most common cause of death in two recent large single-institution retrospective studies of pediatric pelvic fractures (4,14). Other causes of death include multiorgan failure and visceral injuries (4,7,10,14). In children, hemorrhage from pelvic fracture-related vascular injury was the cause of death in only 0.3% compared with 3.4% in adults (7).
Mechanisms of Injury
Between 75% and 95% of pelvic fractures in children result from motor vehicle-related accidents (3,4,10,11,12,13,14,15,17,18,19). In the

largest consecutive series of pediatric pelvic fractures from a single urban level 1 trauma center, the most common mechanism of injury was pedestrian struck by a motor vehicle (60%), followed by passenger in a motor vehicle (22%), and falls (13%) (14). Sporting activities account for between 4% and 11% of pelvic fractures in other series (13,15). Child abuse is a rare cause of pelvic fracture, but isolated fracture of the pelvis may be the only skeletal manifestation of child abuse (20). X-rays of the pelvis should be included in any skeletal survey for child abuse (21). Avulsion injuries most commonly occur secondary to athletic injuries, especially soccer, gymnastics, and track.
Signs and Symptoms
The evaluation of a child with a suspected or documented pelvic fracture begins with a thorough history and physical examination. The associated injuries including closed head injury, and chest, abdomen, and genitourinary injury take precedence over the pelvic fracture in terms of diagnosis, stabilization, and operative intervention. The examination of the pelvic area begins with a visual inspection. Areas of contusion, abrasion, laceration, ecchymosis, or hematoma, especially in the perineal and pelvic areas, should be recorded.
Pelvic landmarks including the anterior superior iliac spine, crest of the ilium, sacroiliac joints, and symphysis pubis should be palpated. Exerting posterior pressure on the anterior superior iliac crest produces pain at the fracture site as the pelvic ring is opened. Compressing the pelvic ring at the iliac crest from lateral to medial 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 motion if there is a fracture in the pelvic ring. The range of motion of the extremities, especially at the hip joint, should be determined. 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. Rectal examination and careful genitourinary evaluation must also be performed as part of the primary evaluation.
Associated Injuries
Because most pelvic fractures in children result from high-energy trauma, multisystem injuries are commonly present. Between 58% and 87% of pelvic fractures have at least one and often several associated injuries (4,6,13,14,22). Of the 57 consecutive children with pelvic fractures reported by Grisoni et al (6), 58% had one or more other body area injuries in addition to the pelvic fracture including nonpelvic fractures (49%), neurologic injury (26%), significant hemorrhage requiring transfusion (21%), abdominal injury (14%), thoracic injury (7%), and genitourinary injury (4%). The incidence of associated injuries increases with the severity of the pelvic fracture. Bond et al (3) noted that the location and number of pelvic fractures were strongly associated with the probability of abdominal injury: % for isolated pubic fractures, 15% for iliac or sacral fractures, and 60% for multiple fractures of the pelvic ring. The data of Grisoni et al did not support this finding, and their study found no association between multiple pelvic fractures and associated abdominal injuries (6). Almost all authors agree that the outcome of patients with pelvic fractures is largely determined by the associated injuries rather than the pelvic fracture itself (3,4,6,7,9,10,13,14,16,22).
The incidence of head injury in association with pelvic fracture is between 9% and 48% in recent retrospective studies (3,4,6,10,11,12,13,14,23). Rieger and Brug (13) reported the highest incidence of head injuries in 48% of the 54 patients in their series, ranging from mild concussion to brain death. The two largest single institution studies of pediatric pelvic fractures reported closed head injuries in 39% (4) and 44% of patients (14). The correlation of pelvic fractures with head injury has been noted by others as well (15). Brain injury merits the highest priority because it is the leading cause of death in patients with pelvic fracture.
Because children’s bones have a lower modulus of elasticity, they deform more and absorb more energy that adult bones before fracture (24). In addition, there is greater elasticity in the sacroiliac joints and symphysis pubis in children, and greater energy is required to cause a fracture in an immature pelvis than in an adult pelvis (14). Thus, the presence of a pelvic fracture in a child is a marker of severe injury that should alert the clinician to search actively for other injuries including abdominal, genitourinary, neurologic, and other fractures (4). Although children with high-energy pelvic fractures often require blood transfusions, exsanguination is rarely the primary cause of death in children with pelvic fractures. In three recent studies, each with between 57 and 166 patients, the incidence of transfusion was between 20% and 30% (4,5,6). In none of these studies did children die of an exsanguinating pelvic fracture or associated vascular injury. Direct vascular injury with marked superior displacement of the hemipelvis can injure the superior and inferior gluteal arteries at the sciatic notch. Other studies on pelvic fractures in children have documented retroperitoneal hemorrhage secondary to injury of primary branches of the iliac artery in relationship to a grossly disrupted sacroiliac joint in children (10,18). Children are thought to have lower incidence of exsanguinating hemorrhage compared with adults because of a more effective vasoconstrictive response in younger patients with nonatherosclerotic blood vessels (7). Only McIntyre et al’s (10) study of pelvic fractures in children correlated the risk of life-threatening hemorrhage to pelvic fracture complexity. In children with unstable fracture patterns or uncontrolled hypotension with ongoing transfusion requirements, external fixation, angiography, and selective embolization may be indicated.
Hematuria is noted on initial urinalysis in 14% to 52% of children with pelvic fractures (4,12,25). The incidence of significant lower urinary tract injuries including bladder rupture or urethral tear has been between 4% and 15% in recent retrospective studies (3,11,12,13,19,26). The two largest single-center retrospective studies of pediatric pelvic fractures by Silber et al (14) and Tarman et al (25) reported a 1% incidence of lower urinary tract injury in association with pelvic fracture. Although controversial, most authors agree that microhematuria can be

followed expectantly, whereas patients with gross hematuria or significant local findings on physical examination should undergo formal urologic assessment. This should include imaging with abdominopelvic computed tomography (CT), retrograde urography, and cystography (25). Pediatric patients should also be carefully screened for the presence of vaginal and/or rectal lacerations because the incidence of these injuries is between 2% and 18% in children with pelvic fractures (11,19,25,27), and early detection and repair or diversion may prevent late pelvic abscess formation (28). The overall incidence of lower urinary tract injury (47%), vaginal laceration (33%), and rectal laceration (66%) is significantly increased in cases of open pelvic fractures (29). Some authors have correlated the presence of multiple pelvic fractures and anterior pelvic fractures with urogenital injury in children (3,9), but the largest series to address this issue found no association between pelvic fracture type or instability and urinary tract injury (25).
The incidence of abdominal injuries including solid organ injury and hollow viscus injury is between 14% and 21% in children with pelvic fractures (3,4,5,11,14). Rapid diagnosis of severe abdominal injury is important because abdominal injury ranks second to head injury as cause of death in children with pelvic fractures (4). The presence of extremity fractures in the presence of a pelvic fracture is associated with increased risk of abdominal injury (16). CT scan best demonstrates evidence of injury to solid organs, hollow viscera, and mesentery after blunt injury to the abdomen (4). The incidence of abdominal injury in association with pelvic fracture is similar in children (13.7%) and adults (16.7%) (5). Ultrasound and diagnostic peritoneal lavage may also be helpful in the diagnosis of intraabdominal injury and vascular injury.
Pelvic fractures with posterior displacement of the hemipelvis or iliac wing can damage the lumbosacral plexus as well as the sciatic nerve. The incidence of lumbosacral plexus injury is low, between 1% and 3% (9,19,22). Myelography with computed axial tomography or alternatively magnetic resonance imaging (MRI) is useful for the diagnosis of lumbosacral plexus injury or root avulsion. Complete neurologic examination of the extremities should be routine, and documentation of any neurologic deficit is essential. Surgical repair of nerve root avulsions is rarely performed, and deficits are usually permanent (30).
Fractures of other bones are present in 40% to 50% of children with pelvic fractures (4,6,10,13,14,22). The most frequently fractured bone is the femur followed by the tibia and fibula. Vazquez and Garcia (16), in a study of 79 children with pelvic fractures, found that the presence of any additional fracture was a significant indication that head or abdominal injury was also present and that transfusion would be required in the first 24 hours after injury. The patients with an additional fracture had twice the frequency of death, thorac injury, laparotomy, and other nonorthopaedic procedures compared with the group with pelvic fractures alone. Vazquez and Garcia (16) suggested that this easily identifiable risk factor can help identify patients who may benefit from early transfer to a regional pediatric trauma center.
Radiographic Studies and Other Imaging
Emergency assessment and stabilization of the child with pelvic trauma should be performed before obtaining survey x-rays because associated injuries account for most of the morbidity and mortality in patients with pelvic fractures. Once the patient is stabilized, pertinent x-rays should be ordered by the physician in charge. Scout views of the skull, cervical spine, chest, abdomen, pelvis, and long bones should be obtained quickly. If special views are necessary, then the physician ordering these films should be in attendance.
In a child with a pelvic fracture, unless there is a significant fracture-dislocation, multiple radiographic views can be deferred. A single anteroposterior x-ray may be sufficient to determine pelvic ring stability in the acute situation (31). The presence of sacroiliac displacement on the anteroposterior view indicates greater instability and the possibility of associated major hemorrhage. Two other views, the inlet and outlet views, are approximately at right angles to each other (31). 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 the pelvis. 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 posterior pelvis or superior or inferior displacement of the anterior portion of the pelvis (31). Internal and external rotation views help to determine fractures of the acetabulum. Comparison views of the contralateral apophysis may be helpful in evaluating avulsion fractures.
CT scanning helps determine the presence of fractures and any disruption or incongruity of the sacroiliac joint, sacrum, or acetabulum. Most authors agree that CT scanning is indicated if there is doubt about the diagnosis on plain x-ray or if operative intervention is planned (32). Some of the advantages of CT over plain x-rays include optimized imaging with CT reconstruction, as well as improved fracture definition, aid in decision making between conservative and operative treatment, and improved operative approaches (33). Others have noted that CT scans of the pelvis are more sensitive than plain x-rays in all anatomic areas including the iliac region, pubis, sacroiliac joint, hip, sacrum, and soft tissues (34). These authors note that pelvic x-rays may be superfluous in pediatric patients who will undergo pelvic CT scan for assessment of soft tissue injuries. MRI offers similar benefits, with the advantages over CT including better delineation of soft tissue injuries, absence of ionizing radiation, and improved imaging of posterior wall fractures in the setting of pediatric hip dislocations in which the posterior wall fragment is largely cartilaginous (35). Rarely, a radioisotope bone scan is useful for the diagnosis of nondisplaced pelvic fractures

and in the identification of acute injuries in children and adults with head injuries or multiple-system injuries (31,36).
Quinby (18) and Rang (37) classified pelvic fractures in children into three categories: uncomplicated or mild fractures, fractures with visceral injury requiring surgical exploration, and 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. Watts (38) 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.
Torode and Zieg (15) retrospectively reviewed 141 children with pelvic fractures and classified the injuries on the basis of the severity of the fractures as well as associated prognosis. Their classification does not include acetabular fractures (Fig. 20-1 and Table 20-1). The morbidity, mortality, and complications were greatest in the type IV group with segmental instability of the pelvis. Pennal et al (39) classified pelvic fractures according to the direction of force producing the injury: (a) anteroposterior compression, (b) lateral compression with or without rotation, and (c) vertical shear. This classification was modified and expanded by Tile et al (Table 20-2) (31). Burgess et al (40) further modified the Pennal system and incorporated subsets to the lateral compression and anteroposterior 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 Pennal et al classification scheme.
FIGURE 20-1 Torode and Zieg classification of pelvic fractures in children: type I, avulsion fractures; type II, iliac wing fractures; type III, simple ring fractures; type IV, ring disruption fractures.
TABLE 20-1 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 ring fractures
    1. Fractures of the pubis and disruption of the pubic symphysis
    2. Fractures involving the acetabulum, without a concomitant ring fracture
  4. Fractures producing an unstable segment (ring disruption fracture)
    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
The Tile classification has been incorporated into the Orthopaedic Trauma Association/AO classification, which is divided into bone segments, type, and groups (Table 20-3) (41). 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 or posterior surgical stabilization or both may be indicated for types B and C. Numerous subtypes are included, and further details are described in the chapter on pelvic fractures in Rockwood and Green’s Fractures in Adults (Volume 2, Chapter 35).
TABLE 20-2 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
TABLE 20-3 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
Silber and Flynn (42) reviewed x-rays 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 in this group rarely required surgical intervention; fractures in the mature group were best classified and treated according to adult pelvic fracture classification and management principles.
The multitude of classification systems makes the comparison of incidence, mechanism of injury, morbidity and mortality, and outcome difficult among studies using different systems. Although many recent studies of children’s fractures use the Torode and Zieg (15) or Tile classifications or both, the basic classifications, (a) mature or immature pelvis and (b) stable or unstable fracture, are very useful information for making treatment decisions. Most pelvic fractures in children are stable injuries. Pelvic fractures in patients with closed triradiate cartilage should follow adult fracture classifications and treatment protocols (31,40,41).
There are several important anatomic differences between the pelvis of a child and that of an adult. First, a child’s pelvis is more malleable because of the nature of the bone itself, the increased elasticity of the joints, and the ability of the more cartilaginous structures to absorb energy (43). Second, the elasticity of the joints may allow significant displacement and resultant fracture in only one area rather than the traditional concept of a mandatory “double break” in the ring for a displaced fracture (37,43). Third, avulsion fractures of an apophysis occur more often in children and adolescents than in adults because of the inherent weakness of cartilage compared with bone; fractures of the acetabulum into the triradiate cartilage also occur more often for the same reason (16,37). Fourth, fractures through physeal cartilage in children can ultimately cause growth arrest, leg-length discrepancy, and abnormal development (e.g., a fracture through the triradiate cartilage with resultant “bony bar” formation and ultimately a deficient and dysplastic acetabulum) (43).
FIGURE 20-2 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 curet. 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.)
Ossification Centers
The pelvis of a child consists of three primary ossification centers: the ilium, ischium, and pubis. The three centers meet at the triradiate cartilage and fuse at approximately 16 to 18 years of age (Fig. 20-2) (43). The pubis and ischium fuse inferiorly at the pubic rami at 6 or 7 years of age. Occasionally, at approximately the time of fusion of the ischium to the pubis, an asymptomatic mass, ischiopubic synchondrosis, is noted radiographically in this area. The child should be treated expectantly, and this should not be confused with a fracture of the pelvis.
The secondary centers of ossification include the iliac crest, ischial apophysis, anterior inferior iliac spine, pubic tubercle, angle of the pubis, ischial spine, and lateral wing of the sacrum. The iliac crest is first seen at 13 to 15 years and fuses at 15 to 17 years of age. The secondary ossification of the ischium is first seen at 15 to 17 years and fuses at 19 years of age, although fusion may be as late as 25 years of age. A center of ossification may be present at the anterior inferior iliac spine at approximately 14 years, fusing at 16 years of age (38,43). These secondary

centers of ossification and the age of appearance and fusion are described so they will not be confused with avulsion fractures.
The acetabulum contains the 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 (44). 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 epiphysis (38,44), 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 forms a significant part 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. 20-3). 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 should not be confused with avulsion fractures or loose bodies in the hip joint.
FIGURE 20-3 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.)
Avulsion Fractures
Avulsion fractures of the pelvis usually occur in adolescent athletes as a result of forceful contraction of the attached muscle while the athlete is actively engaged in activities such as kicking, running, or jumping (45,46,47). The incidence of avulsion fractures is most certainly underrepresented in large hospital-based clinical series because most of these injuries do not result in emergency department visits. The incidence in two large recent series was approximately 4% (12,13). Chronic repetitive traction on the developing iliac apophysis may result in an incomplete avulsion fracture or apophysitis without a history of acute trauma (48,49). The sartorius muscle attaches to the anterior superior iliac spine, the direct head of the rectus femoris attaches to the anterior inferior iliac spine, and the hamstrings and adductors attach to the ischial tuberosity.
Of the 268 pelvic avulsion fractures reported in the four largest series (Table 20-4) (45,46,47,50), 50% were ischial avulsions, 23% were avulsions of the anterior superior iliac spine, and 22% were avulsions of the anterior inferior iliac spine (Fig. 20-4). Avulsions of the lesser trochanter (3%) and iliac apophysis (2%) accounted for the rest.
Mechanism of Injury
The mechanism of injury is thought to be either sudden forceful concentric or eccentric contraction of large muscles, which have their insertion on the pelvic apophyses, or sudden passive lengthening while performing anteroposterior splits during

such activities as gymnastics or dance (46). The distribution of fracture patterns with respect to sporting activity reveals that gymnastics are responsible for the greatest number of acute ischial tuberosity avulsion fractures, whereas soccer is responsible for the greatest numbers of anterior superior and anterior inferior iliac spine avulsion fractures (47). Iliac apophysitis is most frequently associated with long distance running and thought to result from either repetitive muscular contraction and inflammation or subclinical stress fractures of the apophysis (49).
TABLE 20-4 Location of Pelvic Avulsion Fractures in Four Series (268 Fractures)*
Ischium ASIS AIIS Lesser Trochanter Iliac Apophysis
50% 23% 22% 3% 2%
* From Fernbach SK, Wilkinson RH. Avulsion injuries of the pelvis and proximal femur. AJR Am J Roentgenol 1981;137(3):581–584; Metzmaker JN, Pappas AM. Avulsion fractures of the pelvis. Am J Sports Med 1985;13(5):349–358; Rossi F, Dragoni S. Acute avulsion fractures of the pelvis in adolescent competitive athletes: prevalence, location and sports distribution of 203 cases collected. Skeletal Radiol 2001;30(3):127–131; and Sundar M, Carty H. Avulsion fractures of the pelvis in children: a report of 32 fracturesand their outcome. Skeletal Radiol 1994;23(2):85–90; with permission.
FIGURE 20-4 Displaced fracture of the anterosuperior iliac spine.
FIGURE 20-5 A. Anteroposterior x-ray of an anterior inferior iliac spine fracture with displacement. B. Three-year follow-up shows union with no displacement and no pain.
Symptoms usually include localized swelling and tenderness about the site of the avulsion fracture. Motion is limited, and pain may be mild or marked. In patients with chronic avulsions caused by repetitive activity, 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. In this position, if the hip is moved into abduction, more pain is elicited. Patients may also have pain while sitting or moving on the involved tuberosity.
In patients with anterior superior iliac spine avulsions, x-rays show slight displacement of the apophysis (Fig. 20-5). In patients with anterior inferior iliac spine avulsions, x-rays show minimal distal displacement of the fragment. Further displacement is probably prevented because this is a conjoined tendon, and the reflected head of the rectus femoris muscle is intact. Contralateral views can be obtained and compared to ensure that this fragment is not actually a secondary center of ossification, either the os acetabuli or acetabular epiphysis (Fig. 20-5). With ischial tuberosity avulsions, x-rays reveal a large fragment displaced distally compared with the opposite ischial tuberosity (Fig. 20-6). Significant displacement is resisted by the intact sacrotuberous ligament.
Because these avulsion fractures occur primarily through secondary centers of ossification before the center is fused with the pelvis, primarily in children ages 11 to 17 years (45,46,50), 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. Later, exuberant callus formation can occasionally mimic a malignant neoplasm (51). Recognition of the initial fracture is important to avoid unnecessary evaluations such as CT, MRI, and radionuclide scans, and inappropriate biopsy.
FIGURE 20-6 Large ischial tuberosity fracture.

Treatment and Prognosis
Most pelvic avulsion fractures in children do well with conservative nonoperative management including rest, partial weight bearing on crutches for 2 or more weeks, and extremity positioning to minimize muscle stretch. 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 (45,46). Others have suggested that conservative nonoperative treatment is associated with a significantly higher incidence of functional disability and inability to return to competitive athletic activity (Fig. 20-7) (50). On long-term follow-up of 12 patients with ischial avulsions, 8 reported significant reduction in athletic ability and 5 had persistent local symptoms (50). In the largest series published to date, only 3 of 198 competitive adolescent athletes with pelvic avulsion fractures were treated operatively (47). Anecdotally, long-term functional disability and inability to return to preinjury activity levels have been reported in the setting of conservatively managed ischial avulsion fractures (50,52). Controversy exists surrounding the acute management of ischial avulsion fractures, but most agree that excision of the ischial apophysis is indicated in the setting of chronic pain and disability. Some authors recommend open reduction and internal fixation of those rare acute pelvic avulsion fragments displaced more than 1 to 2 cm (53).
FIGURE 20-7 Ischial tuberosity fracture at time of fracture (A) and at 6-month follow-up (B), showing abundant callus formation.
Fractures of the Pubis or Ischium
In children, pelvic rami fractures are usually caused by high-velocity trauma and have a significant number of associated injuries. Reed (12) reported that 45% of the pelvic fractures in children in his series were pubic rami fractures. Rieger and Brug (13) reported that 37% of their series of 54 pelvic fractures in children were “simple ring fractures,” and McIntyre et al (10) reported that 40% of 57 pelvic fractures were “type I” (unilateral anterior) fractures. Silber et al (14) reported that 56% of pelvic fractures in their series of 166 consecutive pediatric pelvic fractures were simple ring fractures (excluding acetabular fractures) and were caused by motor vehicle versus pedestrian mechanism in 60%. Single ramus fractures are more common than multiple rami fractures, and the superior ramus is fractured more often than the inferior ramus (Fig. 20-8) (12).
In patients with isolated pubic ramus fractures, clinical examination reveals pain and possible crepitus at the fracture site; however, there should be little or no motion on deep palpation. CT scanning or inlet and outlet radiographic views are helpful in determining whether any other pelvic fractures are present. If there is significant displacement of the pubic rami, a second

fracture through the pelvic ring should be suspected, although because of the plasticity of bone and elasticity of the symphysis and sacroiliac joints in children, more displacement can be expected than in adults with the same injury. Bed rest until pain subsides, followed by progressive weight bearing, usually is sufficient treatment.
FIGURE 20-8 A. Stable superior pubic ramus fracture. The patient was allowed full weight bearing at 4 weeks postfracture. B. He was asymptomatic and x-ray showed early callus formation.
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 treatment consists of bed rest and progressive weight bearing (Fig. 20-9).
FIGURE 20-9 Nondisplaced fracture through the left ischium and contralateral pubic ramus fracture (A). Follow-up x-ray shows mild displacement and incongruity of the acetabulum and complete healing of the superior pubic ramus fracture (B). Either displacement of the fracture fragments or premature closure of the triradiate cartilage could have contributed tothe incongruity of the femoral head in theacetabulum.
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, and also occur 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. X-rays may show no evidence of fracture for as long as 4 to 6 weeks, and then only faint callus formation may be visible; however, imaging by MRI or a technetium bone scan may reveal increased uptake (36), indicating a stress fracture, 3 to 4 weeks before changes on x-ray. Treatment should consist of discontinuing the activity causing the repetitive stress, along with limited weight bearing on crutches for 4 to 6 weeks.
FIGURE 20-10 X-ray 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 center at the time of the x-ray, the patient was asymptomatic and the mass was considered a variant of normal development.
The ischiopubic synchondrosis usually closes between 4 and 8 years of age (54). X-rays of the ischiopubic junction are at best difficult to interpret and may be misinterpreted as a fracture. Caffey and Ross 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 (55). Bilateral swelling of the synchondrosis was also noted in 47% of children at age 7 years. Irregular mineralization and swelling of the ischiopubic synchondrosis has been called ischiopubic osteochondrosis or van Neck disease (56). As noted above, the radiographic changes are common and usually asymptomatic. If this syndrome is noted in a child older than 10 years of age, a stress fracture may be suspected and treated as such (Fig. 20-10).
Fractures of the Wing of the Ilium (Duverney Fracture)
Direct trauma may cause a fracture of the wing of the ilium, but isolated iliac wing fractures are relatively rare. Reed (12) reported an incidence of 12% in children with fractures of the pelvis. Rieger and Brug (13) reported iliac wing fractures in only three (5.6%) of their patients, and McIntyre et al (10) reported only 7 (12%) in 57 fractures. However, this fracture often occurs in conjunction with other fractures of the pelvis, and thus the overall incidence of iliac wing fractures is probably significantly higher than the incidence of isolated iliac wing fractures.
Displacement of the fracture usually occurs laterally, but it can occur medially or proximally. Severe displacement is prevented by preservation of some of the attachments of the abdominal muscles and the hip abductors. Pain is located over the wing of the ilium, and 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 x-ray of the pelvis where the ilium is poorly seen as a large area of radiolucency. Use of a “hot light” is helpful in making the diagnosis (Fig. 20-11).
Treatment of an iliac wing fracture usually is dictated by the associated injuries. Bed rest in a comfortable position, usually with the leg abducted, is all that is necessary for treatment of the fracture itself. This should be followed by partial weight bearing on crutches until the symptoms are completely resolved.

Regardless of the amount of comminution or displacement, these fractures usually unite without complications or sequelae (Fig. 20-12).
FIGURE 20-11 Minimally displaced fracture of the left iliac wing.
FIGURE 20-12 A. Severely comminuted fracture of the left iliac wing. B. X-ray at 3-month follow-up shows fracture healed with displacement, but the patient was asymptomatic.
Fractures of the Sacrum
Sacral fractures constitute a small fraction of pelvic fractures reported in children. Rieger and Brug (13) 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 (Fig. 20-13). Nine of 166 patients (5.4%) with pelvic fractures in the series by Silber et al (14) had associated sacral fractures, none with

nerve root involvement. These fractures may be significant because they may damage the sacral nerves, resulting in loss of bowel and bladder function.
FIGURE 20-13 A. X-ray suggesting comminuted nondisplaced linear sacral fracture on the left. B. At 6-week follow-up, x-ray shows definite evidence of linear sacral fracture.
Sacral fractures are best diagnosed clinically. Pain and swelling may be present, usually over the lower part of the sacrum. Rectal examination elicits pain on palpation anterior to the sacrum. Occasionally, the fracture fragments may be felt. Repeated bimanual rectal examination with attempts at reduction should be avoided because a tear in the rectum may occur.
The fractures are difficult to see on x-rays. 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 caudad view of the pelvis may reveal a fracture of the body of the sacrum. CT scans and MRI scans are both helpful in the identification of sacral fractures missed on plain radiographic images (34,57,58). In one study comparing x-rays with CT scans in a consecutive series of 103 pediatric trauma patients with pelvic x-rays and pelvic CT scans, only three sacral fractures were identified with plain x-rays whereas nine sacral fractures were identified with CT (Fig. 20-14) (34).
Fractures of the Coccyx
Significant soft tissue injury to the coccyx makes it difficult to determine on x-rays whether a coccygeal fracture has occurred, especially in a child. However, historically, trauma to the coccyx is often refractory to treatment. For this reason, if clinical symptoms are sufficient, an injury to this area in a child should be considered a fracture regardless of whether a fracture can be seen on x-rays.
Coccygeal fractures are not included in most large series of fractures of the pelvis in adults and children, although the coccyx is part of the pelvis. The mechanism of injury is usually similar to that in adults: a direct fall onto the buttocks in the sitting position. 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 persist on sitting for 4 weeks.
FIGURE 20-14 A. A 15-year-old boy with an obvious fracture of the left acetabulum and symphysis pubis diastasis, and a questionable ill-defined sacral fracture. B. CT scan reveals a comminuted displaced sacral fracture.
Lateral x-rays of the coccyx with the hips flexed maximally may reveal the fracture (Fig. 20-15). The coccyx may appear to be acutely angulated as a normal variant, and a fracture may not be seen, or the normal acute angulation may be falsely interpreted as a fracture or dislocation. CT and MRI scanning may be helpful in differentiating between physeal plates and fracture lines (59). Treatment consists of activity restriction and use of an inflated doughnut cushion with return to full activity in 4 to 6 weeks.
Fractures of the Two Ipsilateral Rami
Fractures of the ipsilateral superior and inferior pubic rami comprised 18% of pediatric pelvic fractures in the series of 120 pediatric pelvic fractures reviewed by Chia et al (4). Although these fractures are generally stable, they may be associated with increased incidence of associated injuries to abdominal viscera, especially the genitourinary system including bladder rupture (60). There is a high association as well with head injury, which correlates with the mechanism of injury, which is very often motor vehicle versus pedestrian (15).
Considerable force is necessary to cause this fracture pattern, and other associated fractures should be expected. A general

evaluation should be followed by examination of the pelvis and lower extremities, with special attention to abrasions, contusions, lacerations, and ecchymosis about the pelvis. Palpation reveals discomfort anteriorly, and crepitus at the fracture site may be noted.
FIGURE 20-15 Lateral x-ray with the hips maximally flexed reveals displaced coccygeal fracture in a 14-year-old boy.
Various methods of treatment have been advocated for adults. However, in children, the fracture almost always unites with adequate remodeling of even the most displaced fractures. For this reason, short-term bed rest followed by progressive weight bearing on the involved side is all that is necessary (Fig. 20-16).
FIGURE 20-16 A. Ipsilateral left pubic rami fractures with a contralateral right superior ramus fracture.B. At 2-year follow-up, nonunion of the ipsilateral rami fractures is evident, but the patient is asymptomatic.
Fractures Near or Subluxation of the Symphysis Pubis
Isolated injuries in the symphysis pubis area are rare, primarily because they usually occur in association with disruption of posterior structures such as the sacroiliac joint. Although significant force appears to be necessary to disrupt or fracture the symphysis pubis, isolated disruption of the symphysis pubis can occur (38). Usually, there is some normal elasticity at the symphysis in adults (0.5 mm in men, 1.5 mm in women), and there is probably even more in children, depending on maturity. In children and adolescents diastasis greater than or equal to 2.5 cm or rotational deformity greater than 15 degrees suggests significant instability and the need for reduction (61).
Clinically, exquisite pain is present anteriorly at the symphysis; the legs are externally rotated and often pain is worse in the supine position than in the side-lying position (38). Motion of the hips in flexion, abduction, external rotation, and extension is restricted and painful (fabere sign).
X-rays may reveal subluxation and widening of the symphysis, as if opening a book (62). Offset may be superior, inferior, anterior, or posterior (Fig. 20-17). Furthermore, a fracture near or into the symphysis may produce an equivalent subluxation of the symphysis pubis (Fig. 20-18). Because of the variable normal separation of the symphysis in children of different ages, the amount of traumatic separation may be difficult to evaluate. Watts (38) suggested x-rays with and without lateral compression of the pelvis. More than 1 cm of difference in the width of the symphysis pubis between the two views suggests a symphysis pubis separation. Radiographic evaluation should be performed to specifically exclude sacroiliac joint disruption and

triradiate cartilage fracture because both of these injuries may occur in association with symphysis pubis separation (43).
FIGURE 20-17 Mild symphysis pubis subluxation with superior displacement. At 4-year follow-up, the patient is asymptomatic.
Treatment of isolated fractures or subluxations of the symphysis pubis should consist of bed rest, usually in a side-lying position, especially if other injuries are present. Unilateral Buck’s traction may relieve pain, but it rarely improves alignment of the fracture or subluxation. Application of a spica cast in the lateral position with lateral compression may also reduce the displacement and decrease the length of hospitalization (38). External fixation with an anterior frame may provide immediate stability and allow early mobilization in displaced fractures or severe subluxation (63).
Fractures Near or Subluxation of the Sacroiliac Joint
Fractures near or subluxation of the sacroiliac joint are rare, isolated injuries, probably even less common than isolated fractures at the weaker symphysis pubis. More commonly, disruptions of the sacroiliac joint occur with fractures or dislocations of the anterior portion of the pelvis, causing an instability of the pelvis. Sacroiliac dislocations differ from those in adults in several ways. In children, fractures tend to be incomplete because of partial tearing of the anterior sacroiliac ligaments or epiphyseal iliac fracture adjacent to the joint (43). A subchondral fracture through structurally weak zones of physeal cartilage may leave the sacroiliac joint intact (64). Associated vascular and neurologic injuries may occur, and lumbosacral nerve root avulsions have been described in children with this fracture (30).
FIGURE 20-18 Fracture adjacent to the symphysis pubis with symphysis pubis separation.
Subluxation of the sacroiliac joint should be suspected with high-velocity trauma and injury to the posterior aspect of the pelvis near the sacroiliac joint. In patients with these injuries, the fabere sign is markedly positive on the ipsilateral side (64,65). Comparison views of both sacroiliac joints should be carefully evaluated to determine any asymmetry of the wings of the ilium with increased separation at the sacroiliac joint (Fig. 20-19). Any offset of the distal articular surface of the sacrum and ilium on radiography is an indication of sacroiliac joint disruption. Oblique views for comparison of both sacroiliac joints often are beneficial. Because of the rarity of this subluxation or fracture, multiple views including inlet and outlet views, and axial CT scan may be necessary to ensure there is no anterior fracture (Fig. 20-20).
Bed rest and guarded weight bearing on crutches are probably all the treatment needed for isolated subluxations or fractures. Heeg and Klasen (65) reported sacroiliac joint dislocations in 18 children, 10 of whom had extensive degloving injuries of the posterior pelvis. Ten were treated nonoperatively, six with open reduction and internal fixation, one with open reduction but no internal fixation, and one with external fixation. Disabling long-term sequelae included occasional back pain in six, daily back pain in three, and incomplete neurologic recovery in six.
Unstable Fracture Patterns
Unstable pelvic fracture combinations usually are of three types:
  • Double vertical pubic rami fractures (straddle or floating fractures) or dislocations of the pubis that occur as an anterior double break in the pelvic ring anteriorly
  • Double fractures in the pelvic ring anteriorly and posteriorly, through the bony pelvis, sacroiliac joint, or symphysis pubis (Malgaigne fractures)
  • Multiple crushing injuries that produce at least two severely comminuted fractures in the pelvic ring
Bilateral Fractures of the Inferior and Superior Pubic Rami
Bilateral fractures of both the inferior and superior pubic rami (straddle fractures) cause a floating anterior arch of the pelvic

ring that is inherently unstable (Fig. 20-21), as does dislocation of the symphysis pubis with fractures of both ipsilateral pubic rami. This fracture pattern frequently is associated with bladder or urethral disruption (43).
FIGURE 20-19 Separation of the left sacroiliac joint with asymmetry of the wings of the ilium. A. Careful scrutiny of the x-ray reveals contralateral pubic rami fractures. B. At 2-year follow-up, the sacroiliac joint is slightly wide, but the patient is asymptomatic.
Bilateral fractures of the inferior and superior pubic rami can occur in a fall while straddling a hard object or by lateral compression on the pelvis. The floating fragment usually is displaced superiorly, being pulled in this direction by the rectus abdominis muscles (38). Radiographically, an inlet view most accurately determines the amount of true displacement of the floating fragment.
FIGURE 20-20 Fracture of the superior pubic ramus; occult fractures of the ipsilateral sacrum and the sacroiliac joint at the distal articular surface are also present.
In a child, regardless of the amount of displacement, the fracture should heal and remodeling can be expected. Because this fracture does not involve the weight-bearing portion of the pelvis, it does not cause leg-length discrepancy. Skeletal traction is unnecessary, and a pelvic sling is contraindicated because of the possibility that compression will cause medial displacement of the ilium (38,43).
Treatment should consist simply of supine bed rest in the semi-Fowler position with the hips flexed to relax the abdominal and adductor muscles. If the fracture was caused by lateral compression forces, the lateral decubitus position is contraindicated to avoid medial displacement of the ilium.
Complex Fracture Patterns
Fractures and dislocations of the posterior arch (posterior to the acetabulum) combined with anterior ipsilateral or contralateral fractures or dislocations of the anterior arch (Fig. 20-22) result in instability of the hemipelvis or acetabulum. These unstable fractures are associated with retroperitoneal and intraperitoneal bleeding. Bilateral anterior and posterior fractures are the most likely fracture pattern to cause severe hemorrhage. Initial treatment usually involves replacement of blood volume and stabilization of the child’s overall condition before treatment of the pelvic fractures (9).
Three mechanisms of injury have been implicated in these fractures and fracture-dislocations: anteroposterior compression forces, lateral compression forces, and, with the hip fixed in extension and abduction, indirect forces transmitted proximally along the femoral shaft.
FIGURE 20-21 A. Classic example of a straddle fracture in a 16-year-old girl. B. At 6 weeks after injury, abundant callus formation is present and the fractures have healed.

Aside from the physical signs usually associated with pelvic fractures, leg-length discrepancy and asymmetry of the pelvis also may be present because of the displacement of the hemipelvis. If the measured distance from the umbilicus to the medial malleolus is unequal for the two extremities, and the distance from the anterior superior iliac spine to the medial malleolus is the same, pelvic obliquity or displacement is present rather than true leg-length discrepancy. Inlet and outlet x-rays and CT scan reveal the amount of pelvic displacement.
FIGURE 20-22 An unusual Malgaigne fracture; fracture extends through the ilium into the sacroiliac joint with ipsilateral pubic rami fractures.
Numerous treatment regimens have been successful, depending on the type of fracture and the amount of displacement. For fractures with minimal displacement, bed rest in the lateral recumbent position may be all that is necessary. If lateral displacement is severe, closed manipulation in the lateral decubitus position and spica casting can be used, as described in Chapter 35 in Volume 2 of this series. If the displacement is cephalad only, skeletal traction can be used in a small child. Occasionally, manipulation under anesthesia may be required. After successful manipulation of the fragments, traction on the involved side can be used to maintain the reduction. Open or percutaneous external fixation of the pelvis has been advocated to maintain accurate reduction of the fracture or dislocation, achieve earlier ambulation (toe-touch weight bearing), and decrease pain secondary to instability.
Schwarz et al (66), in a long-term (2–25 years) follow-up of 17 children with nonoperatively treated unstable pelvic fractures, reported moderate to severe pelvic asymmetry in eight patients (66). Measured leg length discrepancies between 2 and 5 cm were reported in five patients. These authors emphasized that reduction of the pelvic ring fractures should be as anatomic as possible because healing in malposition resulted in unsatisfactory results

in half of the cases. Nierenberg et al (67), however, reported excellent or good results after conservative treatment of 20 unstable pelvic fractures in children despite radiographic evidence of deformity. They suggested 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. Silber and Flynn (42), in a retrospective review of 166 consecutive children with pelvic fractures, found that all four patients who required open reduction and internal fixation had a mature pelvis with a closed triradiate cartilage. These reviews suggest that younger children with an immature pelvis are unlikely to require operative intervention; however, treatment of children with unstable pelvic fractures and treatment of adolescents with a “mature” pelvis should follow adult pelvic fracture guidelines.
Operative treatment of pelvic fractures in children is not routinely recommended (68) because (a) exsanguinating hemorrhage is unusual in children, so operative pelvic stabilization to control bleeding rarely is necessary (11,68); (b) pseudarthrosis is rare in children and fixation is not necessary to promote healing; (c) the thick periosteum in children tends to help stabilize the fracture, so surgery usually is not necessary to obtain stability (12); (d) prolonged immobilization is not necessary for fracture healing (67); (e) significant remodeling may occur in skeletally immature patients (Fig. 20-23) (68); and (f) long-term morbidity after pelvic fracture is rare in children (6,11,69). Operative fixation may be indicated to facilitate wound treatment in open fractures, control hemorrhage during resuscitation, allow patient mobility and make nursing care easier, prevent deformity in severely displaced fractures that may not heal or adequately remodel, improve overall patient care in patients with polytrauma, minimize risk of growth disruption, or restore articular congruity.
FIGURE 20-23 A. A 6-year-old child with a Malgaigne fracture with right sacroiliac joint displacement and multiple (four) pubic rami fractures. B. Four weeks after injury. C. At 5-year follow-up, complete remodeling is present.
Keshishyan et al (70) advocated external fixation of complex pelvic fractures, especially in children with polytrauma, and Gordon et al (61) suggested external fixation or open reduction and internal fixation in children older than 8 years of age because spica casting is poorly tolerated in older children. Stiletto et al (71) reported good results after open reduction and internal fixation of unstable pelvic fractures in two toddlers. AO small-fragment instrumentation was used in both. Large retrospective reviews of pediatric pelvic fractures suggest that conservative management is successful in patients with an immature pelvis, but operative management may be indicated for severely unstable or malaligned fractures or acetabular fractures (6,42).

FIGURE 20-24 A. Multiple trauma in this 12-year-old child included three fractures of the pubic rami, disruption and fracture of the sacroiliac joint on the right, and a femoral shaft fracture on the right. B. Computed tomography (CT) shows fracture of the ilium and disruption of the sacroiliac joint. C. After open reduction and internal fixation of the sacroiliac joint and closed intramedullary nailing of the femoral shaft fracture. Note femoral nail inserted through the tip of the greater trochanter.
Severe Multiple or Open Fractures
In patients with crushing injuries, distortion of the pelvis is severe and, in addition to multiple breaks in the pelvic ring, apparent or occult fractures of the sacrum may be present, with or without neurologic involvement. Massive hemorrhage, although common in adults with severe pelvic fractures (5), is much less common in children with pelvic fractures (42). Nevertheless, up to 20% of children with crushed open pelvic fractures in one series died within hours of admission secondary to uncontrolled hemorrhage (29). The overall need for blood transfusion in two large retrospective series including all types of pediatric pelvic fractures was between 21% and 33% (5,6). In the setting of hypovolemic shock, however, emergency measures outlined previously in this chapter may be necessary.
The patient should be stable without evidence of ongoing blood loss before operative intervention, either external fixation or open reduction. The rare patient may also require arterial embolization and placement of an inferior vena cava filter before operative intervention. It is important to recognize these severe pelvic fractures because mobile fracture fragments may penetrate viscera (e.g., the bladder or abdominal viscera), lacerate

the abdominal vascular tree, or cause neurologic involvement (Fig. 20-25). Treatment of these acute soft-tissue injuries should take precedence over realignment of the pelvic architecture, although if possible during emergency surgery such as laparotomy, pelvic stabilization should be achieved quickly with a combination of internal and external fixation as needed while the patient is under general anesthesia. In particular, the application of an external fixator may decrease blood loss by stabilizing mobile, bleeding bone fragments, and decreasing the volume of the pelvis (31,62,63).
FIGURE 20-25 A, B. Complex open type IIIC pelvic fracture in a 3-year-old boy. Vascular (femoral artery and vein) and neurologic injuries were also present. Multiple debridements were required, as were colostomy and vesicostomy. The fractures of the wing of the ilium and pubic rami were fixed with small screws. C. One year after injury. (Courtesy of Dr. Gerry Clancy, Children’s Hospital, Denver, CO.)
Open pelvic fractures are rare in children. Mosheiff et al (29) reported that 13% of 116 pediatric pelvic fractures seen over a 12-year period were open injuries. Fourteen of the 15 children were struck by motor vehicles, and one sustained a gunshot wound. Five children with stable fractures were treated non-operatively, and 10 with unstable fractures were treated operatively: external fixation alone (eight patients), combined external fixation and internal fixation (three patients), and internal fixation alone (two patients). Three of the children died secondary to uncontrollable hemorrhage (two patients) and chest injury (one patient). Eleven of the 12 surviving children had deep wound infection or sepsis, and three had premature physeal closure. Mosheiff and colleagues (29) emphasized that the treatment of the soft tissue injuries depends on stabilization of the pelvis and that external fixation is often insufficient, and posterior internal fixation and stabilization are often necessary.
Acetabular fractures constitute only 6% to 17% of pediatric pelvic fractures, making them very uncommon (6,29,42). 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. The position of the leg with respect to the pelvis and the location of the impact determine the fracture pattern; the magnitude of the force determines the severity of the fracture or fracture-dislocation. Patients with high-energy injuries usually have major associated injuries, whereas isolated acetabular fractures can occur from low-energy forces.
Watts (38) described four types of acetabular fractures in children: (a) small fragments that most often occur with dislocation of the hip, (b) linear fractures that occur in association with

pelvic fractures without displacement and usually are stable, (c) linear fractures with hip joint instability, and (d) fractures secondary to central fracture-dislocation of the hip. More recently, however, acetabular fractures in both adults and children usually are classified by the system of Judet et al (72) and Letournel and Judet (73). A more comprehensive classification is based on the AO comprehensive 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 Chapter 36, Volume 2 of this series.
Radiographic Evaluation
Anteroposterior and lateral views may not adequately show the amount of displacement of acetabular fragments after fracture. Inlet, outlet, and 45-degree oblique (Judet) views often are necessary to appreciate the amount of displacement. CT scanning can be used to determine the amount of acetabular displacement (Fig. 20-26) and whether any retained fragments in the acetabulum are preventing an accurate concentric reduction (74). Three-dimensional CT reconstructions can give an excellent view of the overall fracture pattern but often underestimate minimally displaced fractures, especially posterior acetabular wall fractures in children (Fig. 20-27) (35). Rubel et al (35) recommend MRI as an adjunctive imaging study for all pediatric acetabular fractures because MRI discloses the true size of largely cartilaginous posterior wall fragments in children.
FIGURE 20-26 A. Traumatic dislocation with a small acetabular fragment. B. After reduction, a small fragment is visible, but it is not impeding hip congruity or function. C. At 12 weeks after injury, CT scan reveals that the fragment is from the posterior acetabulum, with mild displacement of the acetabulum posteriorly.
The aim of treatment for acetabular fractures in children is the same as for adults: to restore joint congruity and hip stability. Treatment guidelines in general follow those for adults. Bed rest or non–weight-bearing ambulation with crutches can be used for nondisplaced or minimally (<1 mm) displaced fractures.

Because weight-bearing forces must not be transmitted across the fracture, crutch ambulation is appropriate only for older children who can be relied on to avoid putting weight on the injured limb. Non-weight bearing usually is continued for 6 to 8 weeks. In younger children, this may be shortened to 5 to 6 weeks, and in adolescents (>12 years of age), partial weight bearing should be continued for 3 to 4 more weeks. For fractures in which displacement can be reduced to less than 2 mm, skeletal traction with a traction pin in the distal femur can be used. Because traction must be maintained for 5 to 6 weeks, this option usually is not feasible in older children or adolescents.
FIGURE 20-27 A. Postreduction x-ray of a left hip dislocation in a 12-year-old boy. B. CT scan demonstrates small ossified posterior wall fragments. C. Sagittal magnetic resonance imaging (MRI) demonstrates 90% posterior wall involvement with intraarticular step-off (black arrow). (Reproduced from Rubel IF, Kloen P, Potter HG, Helfet DL. 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.)
Gordon et al (61) 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 for accurate reduction of the acetabulum. In children with open physes, all periacetabular metallic implants should be removed 6 to 18 months after surgery.
Improved outcomes with early (<24 hours) fixation of acetabular fractures in adults have been reported (75), and Gordon et al (61) noted that early fixation is especially important to prevent malunion in young patients in whom healing is rapid.
In addition, anatomic alignment of the triradiate cartilage should be obtained in children. 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 concavity of the acetabulum is in response to the presence of a spherical femoral head and increases during development as a result of interstitial growth in the acetabular cartilage. Cessation of growth of all or part of the triradiate cartilage occurring secondary to fracture may result in a dysplastic acetabulum.
Acetabular dysplasia secondary to growth arrest (bony bridge) of the triradiate cartilage has been reported after trauma to the acetabulum (Fig. 20-28). Heeg et al (76) reported acetabular deformity and subluxation of the hip in two of three patients with premature fusion of the triradiate cartilage. Peterson and Robertson (77) 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. Peterson and Robertson emphasized that early recognition and treatment are essential, before premature closure of the entire physis and development of permanent osseous deformity. The typical dysplastic changes seen after trauma to the triradiate cartilage differ significantly from developmental dysplasia and include both lateralization of the hip joint and acetabular retroversion (78).
FIGURE 20-28 A. Fractures of the left superior and inferior pubic rami and the left ilium with injury to the right triradiate cartilage in a 5-year-old boy. B. Three years after injury, the pubic rami fractures are healed and remodeling has occurred, but acetabular dysplasia, widening of the “teardrop,” and mild subluxation are evident in the right hip. C. At 15 years of age, the sequelae of the mild triradiate cartilage injury are still apparent, but he is not symptomatic.
Bucholz et al (79) noted two main patterns of physeal disturbance 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, which had a poor prognosis with premature closure of the triradiate cartilage caused by formation of a medial osseous bridge (Fig. 20-29). 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. These authors found that acetabular reconstruction was frequently necessary to correct the gradual subluxation of the femoral head.
Surgical Treatment
The surgical treatment varies according to the pattern of the fracture and the direction of the displacement as determined on the preoperative x-rays and CT scans (61) (Table 20-5). Fractures of the posterior wall or posterior column can be approached through a Kocher-Langenbeck approach with the patient either in the lateral decubitus position (isolated posterior wall fracture) or supine (associated posterior column fracture). Anterior column injuries can be approached through an ilioinguinal approach. Some transverse fractures may require an extended iliofemoral approach (80). 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 (81).
The surgeon should be familiar with Judet et al’s (72) treatise on the operative reduction of acetabular fractures and with Le-tournel and Judet’s work before performing this surgery (73). For smaller children and smaller fragments, Watts (38) recommended threaded Kirschner wires for reduction. In larger children, cannulated screws may aid in reduction and provide secure fixation (Fig. 20-30). Small-fragment reconstruction plates,

appropriately contoured, also can be used. Gordon et al (61) described the addition of a small (two- or three-hole) “hook plate” for small or comminuted fragments (Fig. 20-31). Because operative procedures about the hip may be necessary later, the hardware in a child may be removed in this situation.
FIGURE 20-29 Types of triradiate cartilage fractures. A. Normal triradiate cartilage. B. Salter-Harris type I fracture. C. Salter-Harris type V (compression) fracture. (Redrawn from Scuderi G, Bronson MJ. Triradiate cartilage injury: report of two cases and review of the literature. Clin Orthop 1987;217:179–189, with permission.)
Brown et al (82) 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 (∼l20% 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.
TABLE 20-5 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 Sea. Techniques of operative reduction and fixation of pediatric and adolescent pelvic fractures. Oper Tech Orthop 1995;5:95–114; with permission.
Postoperative Management
Small children can be immobilized in a spica cast for 6 weeks. If x-rays 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 x-rays show satisfactory healing, weight bearing is progressed as tolerated. Return to vigorous activities, especially competitive sports is delayed for at least 6 months.
FIGURE 20-30 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.)
FIGURE 20-31 A. Anterior column plate and additional wall “hook” plate. B. Posterior wall buttress plate and hook plate. (From Gordon RG, Karpik K, Hardy SEA. Techniques of operative reduction and fixation of pediatric and adolescent pelvic fractures. Oper Tech Orthop 1995;5:95–114; with permission.)
FIGURE 20-32 Central fracture-dislocation of the hip with injury to the triradiate cartilage in a 15-year-old boy. Note distraction and incongruous reduction. A. During skeletal traction after reduction of the hip dislocation. B. Six months after injury. C. Two years after injury, he has chondrolysis, mild osteonecrosis of the femoral head, and an ankylosed hip.


Because of the remodeling potential and rapid healing in young children, loss of reduction and malunion usually are not problems. Reported complications include premature triradiate cartilage closure, osteonecrosis, traumatic arthritis, sciatic nerve palsy, heterotopic myositis ossificans about the acetabulum and pelvis after acetabular fractures (Fig. 20-32), and pelvic asymmetry at long-term follow-up of female patients. Because this asymmetry may cause maternal dystocia during childbearing, pelvimetry is recommended before pregnancy. Rieger and Brug (13) reported one female patient who required cesarean section because of ossification of the symphysis pubis after nonoperative treatment of an open-book fracture. Schwarz et al (66) reported leg-length discrepancies of 1 to 5 cm in 10 of 17 patients after nonoperative treatment of unstable pelvic fractures; five had low back pain at long-term follow-up. Nine of 10 patients with lumbar scoliosis had low back pain.
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