Pelvis
Pelvic injuries (PI) are frequent, particularly after blunt trauma (9% of all blunt trauma patients), and range from clinically insignificant minor pelvic fractures to life-threatening injuries that produce exsanguination (0.5% of all blunt trauma patients). The overall mortality rate of patients with pelvic ring fractures is approximately 6%. Uncontrolled pelvic hemorrhage accounts for 39% of related deaths, whereas associated head injury is responsible for 31% of the deaths. AP compression and vertical shear injuries are associated with a higher incidence of pelvic vascular injury and hemorrhage. There is little agreement about the preferred methods of management and, therefore, guidelines are vague or not followed. However, the recent evolution of rapid pelvic stabilization by external fixation or pelvic binding and of bleeding control by angiographic embolization or preperitoneal pelvic packing has significantly decreased the mortality rates of devastating PI. A multidisciplinary approach is crucial, as no single specialty has all the skills or controls all the resources that can be used to produce ultimately outcomes. Emergency medicine physicians, trauma and critical care surgeons, orthopedic surgeons, and interventional radiologists should play protagonist roles in a well-orchestrated trauma team that manages these complex patients.
PELVIC ANATOMY
The pelvic ring comprises the sacrum and the two innominate bones, all attached with strong ligaments. The innominate bones join the sacrum at the sacroiliac joints and each other anteriorly at the pubic symphysis. The anterior and posterior sacroiliac ligaments include shorter and longer elements that extend over the sacrum and to the iliac crests, and provide vertical stability across the sacroiliac joints. The pelvic floor is bridged by the sacrospinous and sacrotuberous ligaments that connect the sacrum to the ischial spine and the ischial tuberosity, respectively. The anterior elements, including the pubic rami and pubic symphysis, contribute to approximately 40% of the pelvic stability, but the posterior elements are more important, as shown by biomechanical studies.
The internal iliac (hypogastric) arteries provide blood supply to the organs, bones, and soft tissues of the pelvis. The anterior division includes the inferior gluteal, obturator, inferior vesicular, middle rectal, and internal pudendal artery. The posterior division includes the iliolumbar, lateral sacral, and superior gluteal artery. The largest branch is the superior gluteal artery, which is the most commonly injured major arterial branch after pelvic fractures. Pelvic veins run parallel to the arteries and form an extensive plexus that drains into the internal iliac veins. The sacral venous plexus is adhered to the anterior surface of the sacrum and shredded after major pelvic fractures. Venous bleeding is more frequent than arterial bleeding after PI.
The sciatic nerve is formed by the nerve roots of L4 to S3 and exits the pelvis under the piriformis muscle. The anterior roots of L4 and L5 cross the sacroiliac joints and can be injured in sacral ala fractures or sacroiliac joint dislocations.
All pelvic organs are at risk of injury following severe PI with the bladder and urethra being the most frequently injured. The extraperitoneal rectum is also at risk in open pelvic fractures.
PELVIC FRACTURE CLASSIFICATION
Despite multiple classification systems described, the two most commonly used are those described by Tile1,2 and Young–Burgess.3,4
The Tile classification categorizes pelvic fractures in three groups based on stability, as evaluated primarily by clinical examination and plain radiographs (Table 35-1):
TABLE 35-1 Tile Classification of Pelvic Fractures
• Type A fractures are stable, as the posterior ligaments are intact. These fractures include transverse sacral, iliac wing, pubic rami, pure acetabular, and chip and avulsion fractures.
• Type B fractures are caused by internal and external rotational forces and are “partially” stable (vertically stable but rotationally unstable). They include open-book and bucket-handle fractures (Figs. 35-1 to 35-3).
• Type C fractures are vertically and rotationally unstable, as they involve a complete disruption of the sacroiliac complex (Fig. 35-4).
FIGURE 35-1 Type B1 open-book injury. Diastasis of the pubic symphysis and fracture of the superior or inferior pubic rami may occur.
FIGURE 35-2 Type B2 lateral compression (ipsilateral) injury. Note overriding of the left hemipelvis and crush injury to ipsilateral sacrum and ipsilateral iliac fracture.
FIGURE 35-3 Type B3 lateral compression (contralateral) or bucket-handle injury. Note anterior rami fracture with contralateral posterior sacroiliac injury.
FIGURE 35-4 Type C1 unilateral injury with vertical instability. Involves symphysis disruption or rami fracture with ipsilateral sacroiliac joint or sacral injury.
The Young–Burgess classification divides pelvic fractures according to the vector of the force applied into anteroposterior compression (APC), lateral compression (LC), and vertical shear fractures (Table 35-2):
TABLE 35-2 The Young–Burgess Classification of Pelvic Fractures
• APC injuries are produced by forces applied in the sagittal plane, as is usually the case with motor vehicle crashes. APC-I injuries may result in a small widening of the pubic symphysis (<2.5 cm) but the posterior ligaments are intact. APC-II injuries include tearing of the anterior sacroiliac ligaments, as well as the sacrospinous and sacrotuberous ligaments, but the posterior sacroiliac ligaments are intact. The pubic symphysis diastasis may be more than 2.5 cm. Rotational instability is usually present and hemorrhage more likely. APC-III injuries are caused by high-energy transfer and the posterior sacroiliac ligaments are disrupted, causing full instability of the hemipelvis with a high likelihood of bleeding, nerve damage, and organ injuries.
• LC injuries are produced from lateral impacts across the horizontal plane, also common with motor vehicle crashes. LC-I injuries include transverse fractures of the anterior ring or impacted sacral fractures and are typically stable. LC-II injuries are caused by higher-energy forces that produce tearing of the posterior sacroiliac ligament and displacement of the sacroiliac joint or an oblique fracture of the ilium, the superior part of which remains attached to the sacrum, while the inferior is mobile (crescent fracture). Depending on the force applied, this fracture can be stable or unstable. LC-III injuries are severely unstable fractures, as the lateral force continues to compress and rotate the hemipelvis to the point of complete destruction of the sacroiliac joints, as well as the sacrospinous and sacrotuberous ligaments. Neurovascular and organ injuries are common.
• Vertical shear injuries are typically produced by a fall from a height and involve anterior (pubic rami, pubic symphysis) and posterior (sacroiliac complex) fractures. Typically, they are unstable.
• Combinations of the above types produce a variety of fracture patterns, most commonly involving LC and vertical shear injuries. Nearly one third of PI patients have combination injuries.
DIAGNOSIS
Physical examination will establish the suspicion for a PI and assess for pelvic instability. With the examiner’s hands on the anterior iliac spines of the patient, a gentle compression toward the midline, as well as a mild anteroposterior movement of the hands, will provide evidence of pelvic instability. This must be done by an experienced physician who will interrupt the motion immediately if instability is produced. Aggressive handling of the pelvis, such as “rocking,” is discouraged because it produces pain, bleeding, and aggravation of the injury. Inspection of the perineum is critical to diagnose lacerations or hematomas, which are further indications of significant PI. In a study of 66 patients with Glasgow Coma Score over 12, a focused physical examination protocol, including posterior palpation of the sacrum and sacroiliac joint, anteroposterior and lateral iliac wing compression, active hip range of motion, and a digital rectal examination, resulted in 98% sensitivity and 94% specificity for the detection of posterior pelvic fractures.5
The plain anteroposterior pelvic film is part of the radiographic routine for blunt trauma. However, many studies indicate that in patients with a negative clinical exam for PI, the pelvic film is unnecessary. In a review of 743 blunt trauma patients with no pain or other clinical findings of PI, only 3 patients (0.4%) had a pelvic fracture.6 In all cases it was a single, nondisplaced pubic ramus fracture that required no treatment. In another study of 686 blunt trauma patients, 311 received a pelvic film, which carried a false-negative rate of 32%.7 Of the 375 patients who did not receive a pelvic film, 3% of the patients (13) were found to have small pelvic fractures, none of which required treatment. So, it seems that a routine pelvic film in asymptomatic patients is not useful. Similarly, a pelvic film in patients who have symptoms may be inadequately sensitive and, therefore, might be omitted in favor of a CT scan. In a study of 397 multiple injured patients who had a pelvic film and a CT scan, 43 patients had 109 pelvic fractures.8 The plain film did not diagnose 51 (47%) of the fractures in 9 (21%) patients. Iliac and sacral fractures were most frequently missed. The authors concluded that a screening pelvic film is unnecessary after blunt multitrauma.
Pelvic inlet and outlet films provide information about the anteroposterior displacement of the injury (inlet films) and vertical displacement (outlet films). CT scan with reconstructions (and recently three-dimensional reconstructions) has essentially replaced all other diagnostic modalities and is routinely performed to accurately characterize pelvic fractures, as well as identify associated pelvic organ injuries and hematomas (Fig. 35-5). Intravenous contrast is routinely administered, unless there is a contraindication. Oral and rectal contrast is not necessary for blunt trauma. Magnetic resonance imaging does not offer a distinct advantage over CT scan and is only considered if radiation exposure becomes an issue, as it is with pediatric patients, pregnant patients, or repeat imaging. On occasions, the ligaments need to be evaluated in more detail and this can be done with higher accuracy by magnetic resonance.
FIGURE 35-5 Three-dimensional computed tomographic reconstructions provide a realistic assessment of the anterior and posterior elements in pelvic fractures.
The diagnostic peritoneal lavage has nearly completely disappeared from the algorithms of diagnosis of abdominal bleeding in modern trauma centers. On occasions, we use the aspiration portion of it only (diagnostic peritoneal aspiration) to detect any large volume of intraperitoneal bleeding.9 We perform it percutaneously and, when a PI is suspected, supraumbilically. The focused abdominal sonography for trauma (FAST) exam has become a routine part of the initial evaluation and screening for intra-abdominal fluid. In PI a number of findings can be useful: (1) the absence of intraperitoneal fluid in a hemodynamically unstable patient indicates the presence of a major retroperitoneal hemorrhage from PI; (2) a distorted bladder contour indicates the presence of a compressing pelvic hematoma; (3) the presence of intraperitoneal fluid indicates that intraperitoneal organ injury must be excluded by additional diagnostic methods or laparotomy.
MANAGEMENT OF PELVIC BLEEDING
As soon as significant pelvic bleeding is suspected, the patient should be resuscitated per routine and a decision should be made for additional diagnostic tests or immediate intervention. The concept of hypotensive resuscitation (i.e., allowing a lower than normal blood pressure during the early phases of resuscitation in order to prevent ongoing hemodilution and bleeding) has been adequately established for penetrating trauma.10 However, it is not universally accepted for blunt trauma despite the encouraging reports.11 The coexistence of neurologic injuries, which have been shown to produce worse outcomes in the presence of hypotension, is the main deterrent to allow a low blood pressure in a hemodynamically unstable blunt trauma patient. We espouse the principles of hypotensive resuscitation even in blunt trauma and are very cautious with our early resuscitation efforts, rarely using massive crystalloid infusions. If we suspect correctable bleeding sites, we strive to control bleeding as early as possible and then assume full resuscitation. We pay particular attention to substitute lost blood with blood and blood product transfusion rather than acellular fluids, and we decrease the ratio of packed red blood cells to fresh frozen plasma to as close to 1:1 as possible.12 We are not convinced about the effectiveness of recombinant Factor VIIa, given that there is no Level 1 evidence, supporting the use of this very expensive medication.13 The only prospective randomized study was flawed by excluding early deaths.14 The benefit of patients who received recombinant Factor VIIa compared with placebo was modest at best, a reduction of blood transfusions by 2.6 U among blunt trauma patients. There was no benefit among penetrating trauma patients. Therefore, we use recombinant Factor VIIa only as rescue therapy in very selected cases, if at all.
Pelvic Binders
Unstable pelvic fractures produce bleeding because of ongoing injury to small vessels, as the fractured elements continue to move, and because of the increased volume of the pelvis, as it happens in open-book fractures. Significant bleeding continues unchecked prehospitally and in the emergency department, as the therapeutic choices to counteract these two mechanisms are limited. Pelvic binders address temporarily these two issues by stabilizing the pelvis to stop the movement of the fractured elements and by decreasing the retroperitoneal volume (Fig. 35-6). The former effect can be produced by simply applying a binder with mild to moderate LC of the pelvis. The latter effect is possible only if the device applies significant compression in order to reduce an open pelvis and decrease the volume available for blood to spill. However, significant LC can create the opposite effect, if applied on the wrong type of fracture. For example, a moderately displaced LC fracture can become worse, if excessive compression is applied by a pelvic binder (Fig. 35-7). Under these principles, simple stabilization by a pelvic device is desirable in all unstable fractures but significant compression should only be used in certain fractures, most commonly those of the open-book variety.
FIGURE 35-6 Pelvic binder.
FIGURE 35-7 A fracture that would be inappropriate for a tight pelvic binder. Displacement with forceful lateral compression by the binder could be exacerbated and result in vascular injury.
The military antishock trousers (MAST) garment became popular in the 1980s after initial reports of improved survival in patients with multiple injuries. However, in 1989 a definitive prospective randomized study found it to be associated with increased mortality.15 The MAST was for the most part abandoned, although some emergency medical systems still use it on patients with pelvic or lower-extremity fractures.
Pelvic binders have been commercialized by different companies along the same principles with only a few differences among them. Typically, a binder consists of a wide belt with a velcro that attaches the two ends of the binder (which can be cut to customize its length according to the patient’s body habitus). On the belt there is a “buckle pulley” mechanism. By pulling the strings the binder tightens and compression increases. The device is radiolucent, which allows radiographic imaging with no artifacts. The evidence on the effectiveness of pelvic binders is poor.16,17 There are three major pitfalls related to its use. First, an inappropriately high placement of the binder can lead to excessive abdominal pressure and minimal pelvic stabilization. It is not uncommon to place the binder too high. Correctly, the binder must be centered around the greater trochanters and not over the iliac spines. Usually, it needs to be gently passed under the patient’s back and then pulled slightly lower and over the buttocks for proper placement. Second, indiscriminate pulling of the strings can lead to greater compression than necessary. The binder is frequently placed before the pelvic fracture is fully characterized by a CT scan or even by plain radiographs. Therefore, the initial step should involve only moderate tightening until the exact type of fracture is diagnosed. The pulley mechanism attached on the binder makes tightening very easy, and with minimal force an enthusiastic operator can squeeze the binder tight, producing on occasions more harm than good. Third, the binder may compromise the viability of skin, subcutaneous tissue, or even muscle if left in place for too long. A general guideline of a maximum 24-hour placement exists but obviously even this may be too long after a tight application of the binder.18 The health care providers should understand that the binder is only an imperfect and temporary tool for bleeding control. Definitive pelvic reduction and cessation of hemorrhage should be planned immediately in order to minimize the need for a binder.
A bed sheet is frequently used as an immediately available and inexpensive way to wrap the pelvis.19 The edges of the sheet are tied together and around a stick, which can be turned to tighten the sheet and apply the desired degree of compression (Fig. 35-8).
FIGURE 35-8 A simple sheet wrapped around the pelvis produces inexpensive and adequate reduction of a pelvic fracture. A significant pubic diastasis, as shown in the first image, is reduced by the sheet, as shown in the following image.
External Fixation
External fixation has been popularized as a rapid means of controlling bleeding. In a few institutions this can be accomplished in the emergency room but in most centers the patients are transferred in the operating room. A number of clamps and devices have been used to provide external fixation. The C-clamp was designed for easy placement in the emergency room in the presence of posterior pelvic fracture.20
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