How Common Are Pelvic Injuries? What Injuries Are Associated With Pelvic Trauma?

An 8-year retrospective review of the trauma registry at the Los Angeles County and University of Southern California trauma center found that 9.3% of 16,630 adult admissions sustained some type of pelvic fracture. In patients with pelvic fractures, 16.5% had associated abdominal injuries, including liver (6.1%), bladder and urethra (5.8%), spleen (5.2%), diaphragm (2.1%), and small bowel (2%). In severe pelvic fractures (defined by an Abbreviated Injury Scale score ≥4), intrabdominal injuries rose in frequency to 30.7% of patients, and the bladder and urethra were most commonly injured, in 14.6% of patients. Aortic rupture was seven times more common in patients with pelvic fracture than in those without, although still rare (1.4%, compared with 0.2%).

How Dangerous Are Pelvic Injuries?

Mortality in patients with pelvic fractures is high—13.5% in adults in one large study. However, only about 0.8% of deaths are directly attributed to pelvic injuries. These are high-energy injuries that frequently coexist with severe injuries to the head, chest, abdomen, spine, and extremities. When pelvic injuries are noted on imaging studies, careful attention should be given to determining the presence of other injuries. The low mortality directly attributed to pelvic injuries should not suggest that these injuries themselves are unimportant. This low mortality is achieved when patients are treated at major trauma centers and receive aggressive therapy for pelvic injuries, including blood transfusion, orthopedic fixation, and angiographic embolization of pelvic vascular injuries. In one study, 38.5% of pelvic fracture patients received blood transfusion, with a mean transfusion of nearly 1 L. In severe pelvic fracture patients, 60.6% received transfusion, with a mean of more than 3.5 L. When severe pelvic injury was the only significant injury, more than 50% received transfusion, with a mean of 2.7 L. Overall, 16.6% of pelvic fracture patients required more than 2 L of blood in transfusion. Angiography (discussed in detail in Chapter 16 ) was performed in 4.7% of patients with pelvic injuries, and therapeutic embolization was performed in 2.3%, or half of those undergoing angiography.

Pelvic X-ray and Computed Tomography Techniques

The routine initial view of the pelvis is the anterior–posterior (AP) x-ray ( Figure 13-1 ). This image is obtained with the patient supine and the x-ray beam oriented 90 degrees to the patient’s long axis, passing through the patient from anterior to posterior. Additional plain films can be obtained when injuries are seen on the AP image or if occult injuries are suspected with a normal AP view. These include oblique (Judet) views for characterization of acetabular fractures ( Figure 13-2 ), and inlet and outlet views for characterization of pelvic ring fractures ( Figure 13-3 ). Inlet views are obtained with the patient supine and the x-ray tube positioned at the patient’s head, angled 45 degrees toward the patient’s feet. This allows assessment of pelvic brim integrity, AP displacement of the hemipelvis, internal or external rotation of the hemipelvis, and anterior displacement of the sacrum. Outlet views are also obtained with the patient supine, with the x-ray tube at the patient’s feet and angled 45 degrees toward the head. This provides an excellent view of the sacrum, which is perpendicular to the x-ray beam in this position. The sacral neural foramina are seen well in this view, and vertical displacement of the hemipelvis may be evident. These additional views may be unnecessary if CT of the pelvis is planned, particularly if multiplanar two-dimensional images or three-dimensional models can be constructed, which depends on local software. Most modern picture archiving and communication system (PACS) software allows multiplanar two-dimensional reconstructions from multidetector CT image data, and three-dimensional capability is becoming routine. Three-dimensional reconstruction ( Figure 13-4 ) depends on high-quality original image data but is otherwise a postprocessing function and does not require a different CT protocol during the image acquisition phase.

The normal anterior–posterior pelvis.

This normal pelvis x-ray is from a 24-year-old with no history of direct trauma. Normal findings are labeled. Patients commonly have subtle asymmetry from right to left. Overlying bowel gas frequently hides portions of the bony pelvis, and you will have to make careful judgments about abnormal lucency indicating fracture versus overlying gas.

Oblique (Judet) views of the pelvis for evaluation of the acetabulum.

Oblique (Judet) views of the pelvis are useful for evaluation of the acetabula for fractures. The patient is rolled onto the left and right side at a 45-degree angle, which isolates the hemipelvis and acetabulum, removing posterior pelvic structures from the x-ray path. This provides an en-face view of the dependent iliac wing and places the acetabular lunate surface in relief, preventing overlap by other lines that may simulate or obscure fractures. In this patient, an obvious left acetabular fracture is present, but more subtle fractures may be revealed by this technique. A, An oblique view with left hip in dependent position (called LPO for left posterior oblique) allows evaluation of the left acetabulum. B, An oblique view with right hip in dependent position (called RPO for right posterior oblique) allows evaluation of the right acetabulum. The schematic shows the position of the pelvis relative to the x-ray tube (block arrow).

Inlet and outlet views of the pelvis for evaluation of pelvic ring fractures.

This patient has fractures of the bilateral superior and inferior rami and a vertical sacral fracture seen on computed tomography (arrows in panel A ). An external fixator has been placed. A, Standard anterior–posterior (AP) view for comparison. B, The inlet view reveals the pelvic ring in detail, allowing assessment of pelvic brim integrity, AP displacement of the hemipelvis, internal or external rotation of the hemipelvis, AP displacement of the sacrum, and AP displacement of pubic rami fractures. C, The outlet view provides a good view of the sacrum, which is perpendicular to the x-ray beam in this position. The sacral neural foramina are seen well in this view, and vertical displacement of the hemipelvis may be evident when present. The obturator foramina are also seen well in this view.

Three-dimensional computed tomography (CT) reconstruction of the pelvis.

CT images can be reconstructed in three dimensions using postprocessing software. These CT images were created using axial images from a standard CT scan with intravenous contrast performed for the evaluation of trauma. The patient has a right posterior hip dislocation (A), more evident a posterior view of the pelvis (B) , where the femoral head is exposed rather than hidden within the acetabulum. The acetabulum is also fractured posteriorly. While this model is of high quality, a stair-step pattern is visible in the pelvis because of the relatively thick two-dimensional slices used to reconstruct the three-dimensional model. Higher-quality models can be rendered when thinner slices are acquired during CT. Models can be rotated in three dimensions, and structures can be digitally removed. The aorta, inferior vena cava, and iliac arteries and veins have intentionally been left visible to emphasize the potential for vascular injuries when bony pelvic injuries occur.

Fracture detection with CT does not require the administration of IV or oral contrast. However, in most cases, IV contrast is given because the pelvic CT is obtained with the abdominal CT for detection of visceral injury. IV contrast allows recognition of active bleeding from pelvic vascular structures. Oral contrast is often not administered in the setting of trauma because it has little impact on diagnosis of bowel injuries (see the chapter on imaging of abdominal trauma, Chapter 10 ). A single CT scan of the pelvis can provide information about both soft-tissue and bony injuries. Urinary tract injuries require special CT techniques for diagnosis, as mentioned later and explored in more detail in the chapter on genitourinary imaging ( Chapter 12 ). When more detail of fractures is needed, fine-cut, dedicated “bony pelvis” CT can be performed without contrast, although not all injuries mandate this. In the past, dedicated bony pelvis CT was often obtained to characterize pelvic fractures in greater detail when fractures were seen on body CT performed for evaluation of visceral injury. Today, thin-slice multidetector body CT images offer good resolution of fractures, and bony pelvis CT may not be routinely required. CT images can be reconstructed in three dimensions for further characterization of fractures and dislocations (see Figure 13-4 ).

Interpretation of the Pelvic X-ray

The bony pelvis is a ring structure in which isolated fractures are rare. When reviewing a pelvic x-ray, detection of a single break in the ring mandates search for a second injury. Certain injury patterns are common, and detection of one component of a pattern logically guides your evaluation for the remaining components of the injury. In the figures that follow, a number of frequently encountered fracture patterns are described and illustrated. Figure 13-1 shows a normal pelvis x-ray with labels. Figures 13-5 to 13-19 show common patterns of injury schematically, with displaced fragments highlighted in dark gray. These injuries are also shown in actual x-rays and CTs in the figures that follow. In many cases, multiple injury types are present, so review the schematics first to understand the simplified key features of isolated injuries. Table 13-1 lists the injury patterns and associated figures in this chapter.

The normal pelvis.

This schematic shows a normal pelvis. When reviewing a pelvis x-ray, take the following steps.

• 1.
  

  Inspect the pubic symphysis for widening, overlap, or vertical dislocation, which may be seen the injury patterns described below. The normal pubic symphysis is usually about 4 to 5 mm in width and does not exceed 1 cm.

  
  
• 2.
  

  Inspect the sacroiliac joints for widening, excessive overlap, or vertical off-set. The normal sacrum and iliac wing share a thin zone of overlap defining the sacroiliac joint. Widening of this joint space is abnormal and suggests joint injury and diastasis. The joints should be bilaterally symmetrical. The normal sacroiliac joint is 2 to 4 mm in width.

  
  
• 3.
  

  Examine the sacrum for fractures, which may intersect the normal neural foramina. If the sacroiliac joints are intact but the right and left pelvis are malaligned vertically, suspect a vertically oriented sacral fracture.

  
  
• 4.
  

  Follow the ring formed by the inferior portion of the sacrum and the medial portion of the ilium and ischium, sweeping down the pubic bone to the pubic symphysis and back up the opposite side to your starting point. This should form a smooth continuous ring without cortical irregularities.

  
  
• 5.
  

  Inspect the smaller ring formed between the inferior and superior pubic rami, called the obturator foramen. This should be a smooth continuous circle. The opposite side usually provides an excellent comparison view, unless bilateral injuries are present. Inspect the superior and inferior pubic rami for discontinuities.

  
  
• 6.
  

  Inspect the iliac wings for fractures. Overlying bowel gas may create rounded lucencies overlying the iliac bones, whereas linear lucencies are more suggestive of fracture. Follow lucencies to determine whether they intersect the outer border of the iliac bones, which should be smooth continuous curves without cortical stepoffs.

  
  
• 7.
  

  Inspect the acetabula bilaterally, noting whether the femoral heads are located appropriately or dislocated. The curved concave surface of the acetabulum, called the lunate surface, should be a smooth continuous curve, matching the curve of the femoral head. Clues to acetabular fractures include disruption of the iliopubic line, ilioischial line, and lunate surface. The joint spaces separating the femoral head and lunate surface of the acetabulum should be bilaterally symmetrical.

  
  
• 8.
  

  Inspect the femur, including the femoral head, neck, and intertrochanteric region, as these are common sites of fracture, particularly in elderly patients.

Open-book pelvis.

This schematic of an open-book pelvis shows separation of the pubic symphysis and right sacroiliac joint. Diastasis of the pubic symphysis, combined with either diastasis of one or both sacroiliac joints or fractures of the pelvis ring, allows the pelvis to “open” anteriorly, with a hinge joint posteriorly. The darkened region indicates the portion of the pelvis that has become traumatically displaced.

Vertical shear injury.

Vertical shear can separate the pubic symphysis and sacroiliac joints in a cephalad–caudad direction. Alternatively, fractures may occur vertically, allowing vertical offset of the pelvis. In this schematic, the right sacroiliac joint and pubic symphysis are diastatic. The darkened region indicates the portion of the pelvis that has become traumatically displaced.

Pubic ramus fractures with vertical shear: Bucket-handle pattern.

When pubic rami fractures and sacroiliac joint diastasis are contralateral, a bucket-handle pattern is present. In this schematic, the right pubic rami are fractured, and the left sacroiliac joint is diastatic. Because the pubic symphysis is intact, the left pelvis carried the small right pubic fragment with it in its cephalad migration. The darkened region indicates the portion of the pelvis that has become traumatically displaced.

Pubic ramus fractures with vertical shear: Malgaigne pattern.

When pubic rami fractures and sacroiliac joint diastasis (or sacral fracture) are ipsilateral, a vertical shear injury called a Malgaigne fracture is present. A common mechanism is landing from height on an outstretched leg. In this schematic, the right sacroiliac joint is diastatic and the right pubic rami are fractured. Because the pubic symphysis is intact, the small right pubic bone fragment remains attached to the left pelvis, whereas the entire right pelvis moves cephalad. The darkened region indicates the portion of the pelvis that has become traumatically displaced.

Sacral fractures.

Sacral fractures may occur in isolation or with other fractures. Vertical sacral fractures can occur with vertical pelvic shear, and commonly other fractures or diastasis of the pubic symphysis are seen. Transverse fracture of the sacrum may be seen in isolation and may not compromise the integrity of the pelvic ring. In this schematic, a vertical sacral fracture is depicted with vertical offset of the pubic symphysis. The darkened region indicates the portion of the pelvis that has become traumatically displaced.

Transverse sacral fracture.

Transverse sacral and coccygeal fractures may occur with little clinical consequence because they do not affect the structural integrity of the pelvic ring. Transverse sacral fractures may intersect sacral nerve foramen, with potential for nerve injury. In this schematic, a transverse sacral fracture is depicted intersecting sacral foramen.

Lateral compression of the pelvis.

Lateral compression of the pelvis can disrupt the pelvic ring anteriorly and posteriorly. Commonly, one sacroiliac joint folds inward, although sacral or iliac wing fractures may occur. Anteriorly, pubic rami fractures are common, as well as disruptions of the sacroiliac joint. In this schematic, the right sacroiliac joint has folded inward and the right superior and inferior pubic rami have fractured. The darkened region indicates the portion of the pelvis that has become traumatically displaced.

Pubic ramus fractures.

Pubic ramus fractures, as in this schematic, either occur singly or involve the superior and inferior pubic rami. Usually, a single fracture occurs only if minimally displaced. An offset of a single fracture usually creates tension in the pelvic ring that is relieved through a second fracture or diastasis of a joint.

Iliac wing fracture.

Inspect the iliac wings for fractures. Overlying bowel gas may create rounded lucencies overlying the iliac bones, whereas linear lucencies are more suggestive of fracture. Follow lucencies to determine whether they intersect the outer border of the iliac bones, which should be smooth continuous curves without cortical step-offs.

Acetabular fractures.

Acetabular fractures can be subtle on x-ray and are best diagnosed by computed tomography. Clues to the diagnosis are disruptions of the iliopubic line, which forms the medial border of the anterior column of the acetabulum; disruption of the ilioischial line, which forms the medial border of the posterior column of the acetabulum; and disruptions of the articular surface of the acetabulum, called the lunate surface. In this schematic, defects in each of these lines are shown by short arrows on the patient’s right, whereas the patient’s left side is normal. In an actual x-ray, fracture fragments may or may not be visible.

Posterior hip dislocation.

Hip dislocation most frequently occurs in a posterior direction, with a common scenario being anterior-posterior force directly against a flexed and adducted hip in a seated patient in a vehicle collision. If the hip is abducted at the moment of impact, anterior dislocation sometimes occurs. Once dislocated posteriorly, as in this schematic, the femur is usually pulled cephalad by hip flexors. The darkened region indicates the traumatically dislocated hip.

Anterior hip dislocation.

Anterior hip dislocation, shown in this schematic, is less common than posterior dislocation but may position the femoral head medially relative to the acetabulum. The darkened region indicates the traumatically dislocated hip.

Femoral neck (hip) fracture.

Fractures of the femoral neck can be overt or subtle. Often, these occur in older patients with osteopenia, making cortical and trabecular abnormalities more difficult to see. In this schematic, an obvious fracture is diagrammed on the right, whereas a more subtle fracture is depicted on the left. Sometimes all that is seen is a faint band of increased density in nondisplaced fractures. Magnetic resonance imaging, computed tomography, or bone scan can clarify equivocal fractures.

Intertrochanteric femoral (hip) fracture.

Intertrochanteric hip fractures are a common form of fracture in patients over the age of 65 years, with relatively minor mechanisms of injury, such as falls from standing, predominating. As the name suggests, they typically run between the greater and the lesser trochanters. They may be comminuted and displaced. Sometimes, these fractures are more subtle and require magnetic resonance imaging, computed tomography, or bone scan for confirmation. In this schematic, an overt intertrochanteric fracture is depicted on the patient’s right, with a more subtle abnormality on the left.

We begin with the normal AP pelvis x-ray (labeled, see Figure 13-1 ). Each structure examined on x-ray should also be reviewed when interpreting CT scan. Stepwise inspection of the AP pelvic x-ray should include evaluation of the following (see Figure 13-5 ):

• 1.
  

  Inspect the pubic symphysis for widening, overlap, or vertical dislocation, which may be seen with the injury patterns described later. The normal pubic symphysis is usually about 4 to 5 mm in width and does not exceed 1 cm. Figures 13-6 and 13-7 illustrate some common patterns of abnormality of the symphysis pubis.

  
  
• 2.
  

  Inspect the sacroiliac joints for widening, excessive overlap, or vertical offset. The normal sacrum and iliac wing share a thin zone of overlap defining the sacroiliac joint on the AP view. Widening of this joint space is abnormal and suggests joint injury and diastasis. The joints should be bilaterally symmetrical. The normal sacroiliac joint is 2 to 4 mm in width. Figures 13-6 to 13-9 show abnormal sacroiliac joints.

  
  
• 3.
  

  Examine the sacrum for fractures, which may intersect the normal neural foramina. If the sacroiliac joints are intact but the right and left pelvis are malaligned vertically, suspect a vertically oriented sacral fracture. Transverse sacral fractures may sometimes occur in isolation and may not disrupt the integrity of the pelvic ring. Figures 13-10 and 13-11 depict sacral fractures.

  
  
• 4.
  

  Follow the ring formed by the inferior portion of the sacrum and the medial portion of the ilium and ischium, sweeping down the pubic bone to the pubic symphysis and back up the opposite side to your starting point. This should form a smooth, continuous ring without cortical irregularities. Figures 13-6 to 13-13 show abnormalities in this contour associated with different fracture patterns.

  
  
• 5.
  

  Inspect the smaller ring formed between the inferior and the superior pubic rami, called the obturator foramen. This should be a smooth, continuous circle. The opposite side usually provides an excellent comparison view, unless bilateral injuries are present. Inspect the superior and inferior pubic rami for discontinuities. Figures 13-8, 13-9, 13-12, and 13-13 show fractures involving the pubic rami and obturator foramen.

  
  
• 6.
  

  Inspect the iliac wings for fractures. Overlying bowel gas may create rounded lucencies overlying the iliac bones, whereas linear lucencies are more suggestive of fracture. Follow lucencies to determine whether they intersect the outer border of the iliac bones, which should be smooth, continuous curves without cortical step-offs. Figure 13-14 depicts an isolated iliac wing fracture.

  
  
• 7.
  

  Inspect the acetabula bilaterally, noting whether the femoral heads are located appropriately or dislocated. The curved concave surface of the acetabulum, called the lunate surface, should be a smooth, continuous curve, matching the curve of the femoral head. Clues to acetabular fractures include disruption of the iliopubic line, ilioischial line, and lunate surface ( Figure 13-15 ). The joint spaces separating the femoral head and lunate surface of the acetabulum should be bilaterally symmetrical. Figures 13-16 and 13-17 depict posterior and anterior dislocations of the femoral head (hip).

  
  
• 8.
  

  Inspect the femur, including the femoral head, neck, and intertrochanteric region because these are common sites of fracture, particularly in elderly patients. Figures 13-18 and 13-19 illustrate some common patterns of proximal femur fracture.

Patterns of Pelvic Injury

Fractures of the pelvis can range from innocuous, requiring no treatment, to immediately life threatening. Their appearance on x-ray can be subtle or overt, and the emergency physician must be able to recognize key injuries immediately to take appropriate stabilization measures, plan interventions such as angiographic embolization, consider additional imaging, and arrange safe disposition. We examine a number of common fracture patterns, recognizing that often a mixture of injury patterns may be present in the same patient.

Two major systems of classification of pelvic fractures are the Young-Burgess classification and the Tile classification systems ( Tables 13-2 and 13-3 ). The Young-Burgess classification describes injuries in terms of mechanism and type of injury, direction of hemipelvis displacement, and stability. The Tile classification divides fractures into three main categories, each with multiple subtypes, including stable fractures with an intact posterior arch (type A), unstable anterior and lateral compression fractures with incomplete disruption of the posterior arch (type B), and vertical shear injuries with complete disruption of the posterior arch (type C). While these are useful for orthopedists in surgical planning, emergency physicians can understand injuries and communicate them clearly to specialty colleagues with simple descriptions, based on recognition of several common injury patterns.

Two primary categories of injury should be considered from an emergency medicine perspective: fractures that disrupt the major pelvic ring and those that do not. Fractures that compress or open the pelvis ring can disrupt blood vessels passing through the pelvis. In addition, because they change the geometry of the pelvis from a stable cone with a fixed volume to an expandable structure with the ability to increase in size, substantial bleeding can occur in the pelvis from these fracture types. Identification of a fracture in this group should prompt pelvic stabilization, preparation for potentially massive transfusion, and consideration of angiographic embolization. Fractures that do not affect the pelvic ring in this way can be important for other reasons, but rarely are they as immediately life-threatening. For example, fractures near the pubic symphysis involving the inferior or superior pubic rami may be associated with bladder and urethral injuries, as well as vaginal lacerations in female patients. Acetabular fractures, while associated with disability from posttraumatic arthritis, do not pose an immediate life-threat to the patient.

Forces That Disrupt the Major Pelvic Ring

Fractures that affect the stability of the pelvic ring can be subcategorized in several additional ways—for example, by mechanism of injury. In theory, fractures that compress the pelvic ring laterally may be less likely to stretch and tear vascular structures, compared with structures that involve AP compression, opening the pelvis at the pubic symphysis and sacroiliac joints. Vertical shear injuries to the pelvis may disrupt vascular structures and result in damage to nerve roots at the level of the sacrum. Important pelvic ring disruptions involve fractures or diastasis of joints at two or more sites of the anterior and posterior pelvic arcs. Separation of the pubic symphysis and diastasis of the sacroiliac joints can cause pelvic ring disruption in the absence of a fracture. Two or more fractures can also result in pelvic ring disruption. A combination of one fracture and one diastatic joint may also occur. Because the bony pelvis is a ring, a single disruption usually does not occur; rather, a disruption in one location results in fracture or diastasis at a second point in the ring. When one disruption in the pelvis ring is seen, a second should be suspected and sought. Sometimes the second disruption is at the pubic symphysis or sacroiliac joint and may be unapparent on x-ray because these joints can open and close with repositioning of the patient once the joint has been destabilized.

Anterior-posterior compression injuries

AP compression of the pelvic ring typically separates the pubic symphysis anteriorly while opening the sacroiliac joint posteriorly ( Figures 13-20 to 13-30 ; see also Figure 13-6 ). This fracture pattern is often called an open-book pelvic fracture and can be a life-threatening injury. It results from substantial force and can shear pelvic veins and arteries. Significant bleeding into the pelvis often occurs with this injury. Because this injury increases the volume of the potential space within the pelvis, tamponade of bleeding does not occur, and the patient’s entire blood volume can be accommodated within the pelvis. When this injury is recognized on x-ray or on CT scan, the pelvis should be closed using some type of external compression device. Urethral injuries are also associated with this type of pelvic injury. Evaluation of urethral injury is discussed in detail in the chapter on the genitourinary system ( Chapter 12 ).

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