Chapter 272: Pelvis Injuries

Most pelvic fractures are secondary to automobile passenger or pedestrian accidents but are also the result of minor falls in older persons and from major falls or crush injuries. The mortality rate from all pelvic fractures is approximately 5%. However, with complex pelvic fractures, the mortality rate is about 20%.¹ Isolated fractures of the pubic rami are likely in the elderly who sustain a low-energy mechanism of injury, such as falling off a chair, and are due to underlying fragility and osteopenia.²

The major functions of the pelvis are protection, support, and hematopoiesis. The pelvis consists of the sacrum and coccyx as well as the bilateral "innominate bones," which are comprised of three separate bones: the ischium, ilium, and pubis. These bones provide pelvic stability that is further supported by the strong posterior sacroiliac (SI), sacrotuberous, and sacrospinous ligaments (Figures 272-1 and 272-2). A small amount of pelvic stability is also provided by the pubic symphysis. The bladder lies in close proximity to the symphysis, as does the rectum to the sacrum, putting each of the structures at risk for injury in a trauma patient.

Incorporated in the pelvic structure are five joints that allow some movement in the bony ring. The lumbosacral, sacroiliac, and sacrococcygeal joints, as well as the symphysis pubis, allow little movement. The acetabulum is a ball-and-socket joint that is divided into three portions: the iliac portion, or superior dome, is the chief weight-bearing surface; the inner wall consists of the pubis and is thin and easily fractured; and the posterior acetabulum is derived from the thick ischium. Any single break in the ring will yield a stable injury without significant risk of displacement, whereas the occurrence of two breaks in the ring is considered an unstable pelvis.

The pelvis is extremely vascular. The iliac artery and venous trunks pass near the sacroiliac joints bilaterally. The nerve supply through the pelvis is derived from the lumbar and sacral plexuses. Injury to the pelvis may produce deficits at any level from the nerve root to small peripheral branches (Figure 272-3). The lower urinary tract is contained in the pelvis (Figure 272-4). In the adult, the bladder lies behind the symphysis and pubic bones, and the peritoneum covers the dome and base posteriorly. The location of the bladder and the degree of peritoneal reflection are determined by urine content. The lower GI tract housed in the pelvis includes a small portion of the descending colon, the sigmoid colon, the rectum, and the anus. In women, the uterus and vagina are also housed in the bony pelvis.

HISTORY

Consider the possibility of pelvic fracture in every patient with serious blunt trauma (e.g., falls from a height, pedestrian hit by a motor vehicle, crush injury, individuals ejected from a vehicle). Determine the mechanism of injury and the prehospital evaluation and treatment. Ask the patient about areas of pain, last urination or defecation, present bladder sensation, and last solid and fluid intake. In addition, determine the time of the last menses or the presence of pregnancy, brief past medical history, current medications, and allergies.

PHYSICAL EXAMINATION

In patients who are awake and alert, a careful physical examination is likely very sensitive (93% in one study) for the diagnosis of a pelvic fracture.³ Symptoms and signs of pelvic injuries vary from local pain and tenderness, or inability to bear weight, to pelvic instability and severe shock. Unexplained hypotension may be the only sign of a major pelvic disruption.

Serious Injury

For a patient with a serious or high-energy mechanism of injury, examine for abdominal tenderness, perineal and pelvic ecchymoses, lacerations, and deformities. Scrotal hematoma (Destot's sign) indicates a pelvic fracture. Leg length discrepancy or rotational deformity of the lower extremity without an obvious fracture suggests a pelvic fracture. Evidence of blood at the urethral meatus suggests a urethral injury.

Perform focused abdominal sonogram for trauma (FAST) examination as an adjunct to the physical examination during the primary trauma survey in any unstable patient or when the mechanism of injury could suggest a pelvic fracture. Fluid in the peritoneum can suggest solid organ injury, but fluid in the pelvis can also lead the clinician to suspect a pelvic fracture prior to radiologic confirmation.

Do not perform compressive pelvic maneuvers in a patient with shock or an obvious pelvis fracture because movement of unstable fractures could produce further injury and blood loss.

However, some type of assessment for pelvic instability should be done on every trauma patient, which could include only visual inspection in patients with obvious pelvic fractures, physical examination by pelvic rim compression, or radiologic survey. Gentle downward and medial manual compression of the pelvis over the iliac wings should be performed only once during the trauma survey. Repeated manipulation of the pelvic ring on any patient with a suspected pelvic fracture can increase the severity of injury, resulting in greater blood loss. Rectal examination may detect superior or posterior displacement of the prostate, rectal injury, or an abnormal bony prominence or large hematoma or tenderness along the suspected fracture line. Proctoscopic and/or bimanual pelvic examination may be required to fully assess mucosal tears in order to properly diagnosis open fractures. Such injuries increase the risk of infection at the fracture site and sepsis.⁴ Decrease in anal sphincter tone may suggest neurologic injury. Carefully evaluate lower extremity pulses and sensation. If a pelvic fracture is found, assume intra-abdominal, retroperitoneal, gynecologic, and urologic injuries until proven otherwise.

Stable Patient and Low Mechanism of Injury

In stable patients and those with a low-energy mechanism of injury, such as in the elderly patient who falls from a seated position, examine the entire spine and the abdomen. Palpate for tenderness along the pelvic bony structures—the iliac crests, pubic rami, sacrum, and coccyx. Compress the pelvis, lateral to medial, through the iliac crests as well as through the greater trochanters. Additionally, compress the pelvic ring from anterior to posterior through the symphysis pubis and iliac crests. Evaluate lower extremity pulses, motor function, and sensation.

The initial stabilization of the patient takes priority over obtaining radiographs. If not already done, perform a FAST scan to identify intraperitoneal bleeding.

In patients with suspected hip fracture, a standard anteroposterior pelvis radiograph is often used to evaluate for bony injury. If there is no tenderness to palpation in an otherwise stable, alert patient, then a plain pelvic radiograph is not indicated.^5,6 Indications for a pelvis radiograph include a hemodynamically unstable blunt trauma patient, pelvic tenderness, or other finding on physical examination concerning for pelvic fracture. With an unstable blunt trauma patient, a pelvic radiograph can be used to identify a pelvic fracture quickly, allow early stabilization maneuvers, and mobilize resources for emergent angiography. Routine pelvic radiographs are not needed in stable patients who will undergo an emergency CT scan of the abdomen and pelvis anyway.^7,8,9,10

CT is the gold standard for evaluating pelvic injuries. CT is more sensitive than plain radiographs for the detection of pelvic fractures; plain radiographs rarely change the management plan in stable patients. Compared with CT, pelvic radiographs have a sensitivity of ≤85% for identifying pelvic fractures in blunt trauma patients.² CT is also superior to radiography in evaluating pelvic ring instability.^7,8,9,11 Therefore, indications for CT include a high clinical suspicion for pelvic fracture but negative pelvic radiographs, or pelvic fractures on plain films with need to evaluate for additional pelvic fractures and instability. Contrast-enhanced CT provides useful information about posterior pelvic ring ligamentous injuries, contrast extravasation, pelvic hematoma, and retroperitoneal bleeding. Contrast extravasation on CT scan is 80% to 90% sensitive for the identification of arterial bleeding.^12,13

If additional radiograph views are needed for stable patients, obtain lateral views, anteroposterior views of either hemipelvis, internal and external oblique views of the hemipelvis, or inlet and outlet views of the pelvis. An inlet view shows anterior-posterior displacement of ring fractures. An outlet view shows superior-inferior displacement. Oblique views of the hemipelvis are true anteroposterior and lateral views of the acetabulum. Sacral fractures may be difficult to visualize on plain films, so obtain CT or three-dimensional reconstruction of CT images when there is concern.¹⁴

Extremes of age require different approaches for pelvic imaging. Up to half of elderly patients with a low-energy mechanism and pubic ramus fracture may have an associated posterior pelvic ring disruption demonstrated on CT scan.¹⁵ Pain on sacral palpation may suggest posterior ring disruption and indicate the need for pelvic CT scan. This often overlooked finding may contribute to the fact that one third of the elderly with isolated rami fractures do not return to their previous living independence or may fail conservative treatment for pain management.¹⁵ Most children with a low-energy mechanism and normal examination do not usually require even plain radiographs, because pelvic fractures are rare in young children. Avulsion/iliac wing fractures from sports injuries are reportedly the most common pelvic injuries in children.¹⁶ Clinical scenarios that have been associated with a pelvic fracture in children include a high-risk mechanism (e.g., motor vehicle collision with/without ejection or rollover; automobile versus pedestrian or bicycle) combined with either a Glasgow coma scale score <14 or pelvic tenderness.¹⁷ Other associations with serious pelvic fractures in children include medically complex children, preexisting bone disease, or developmental delay.¹⁶

Pelvic fractures include those that involve a break in the pelvic ring, fractures of a single bone without a break in the pelvic ring, and acetabular fractures. Pelvic fractures involving a break in the pelvic ring can be complex and difficult to classify.

The most clinically useful classification, the Young-Burgess Pelvis Fracture Classification System, is presented in a simplified version in Table 272-1. This system differentiates fracture patterns based on mechanism of injury and direction of causative force. Incidence of complications (i.e., urogenital and vascular) is correlated with the fracture pattern, making identification of the type more clinically significant and useful.

There are three main types of pelvic fracture patterns: lateral compression, anterior-posterior compression (open-book), and vertical shear. The different injury types may be suggested by history but may often be differentiated radiographically. The alignment of pubic rami fractures is a clue to the mechanism and direction of force. In general, horizontal fractures suggest lateral compression injury, whereas vertical fractures point to vertical shear force. Open-book fractures point to an anteroposterior injury. Based on the recognition of the fracture pattern, one can then predict the likelihood of severe hemorrhage or urogenital injury (Table 272-1).

LATERAL COMPRESSION FRACTURE

Lateral compression fractures are the most common mechanism, accounting for 60% to 70% of pelvic fractures with an overall mortality rate of 8%.¹⁸ Motor vehicle crashes in which a car is broadsided or a pedestrian is struck from the side are examples. At a minimum, a pubic ramus will be fractured. As the pelvis is further compressed and the degree of injury progresses, the sacroiliac joint is crushed, leading to disruption of the posterior ligaments, fracture of the sacrum, and rotation of the contralateral hemipelvis. (Figure 272-5).

ANTERIOR-POSTERIOR COMPRESSION OR OPEN-BOOK FRACTURE

Anterior-posterior compression, or open-book fracture, accounts for about 25% of severe injuries. A head-on motor vehicle crash is the classic example. The force is delivered in an anteroposterior direction (arrow in Figure 272-6), tending to "open" the pelvis. This splays the pubic symphysis and ruptures the sacral ligaments (Figure 272-6). Finally, total disruption of the sacroiliac joint will occur because of the wide "opening" of the pelvis. All supporting ligament groups, including the posterior sacroiliac ligaments, can be disrupted.

VERTICAL SHEAR FRACTURE

The least common mechanism is vertical shear fractures, which are typified by a fall or jump from a height, accounting for approximately 5% of fractures. Combinations of injury patterns can make up the other 20% to 25% of injuries. In vertical shear injury, the injury force vector is delivered in a vertical plane (Figure 272-7). Fractures of the pubic rami are usually seen anteriorly, whereas fractures of the sacrum, sacroiliac joint, or iliac wing are usually seen posteriorly. Any of the pelvic ligaments may be disrupted.

Isolated, closed avulsion fractures of the pelvis or single-bone, closed pelvic fractures are more commonly encountered in the ED than pelvic ring disruptions. It is important to know which of these subsets of fractures require further diagnostic testing, orthopedic consultation, or admission.

Isolated fractures of the anterior superior iliac spine, anterior inferior iliac spine, ischial tuberosity, pubic ramus, body of the ischium, iliac wing, sacrum, or coccyx typically do not disrupt the pelvic ring and, as a result, typically do not require surgical repair (Figure 272-8 and Table 272-2). Most of these fractures require only appropriate analgesia, crutches, either bed rest or non–weight-bearing status, and orthopedic follow-up on an outpatient basis.

Simple fractures in the elderly may not be as benign as at first glance. If indicated by physical exam or mechanism of injury, obtain a CT scan of the pelvis with bone windows to detect occult posterior pelvic ring disruption that will alter management (Figures 272-9 and 272-10).¹⁵ Although isolated pelvic ramus fractures are frequently due to low-impact trauma (e.g., fall from standing) in the elderly, isolated pelvic fractures still result in an increased rates of hospital admission, morbidity, need for living assistance after hospital discharge, and overall mortality at 1 year.¹⁹

Pay special attention to isolated fractures of either the sacrum or iliac wing due to the tremendous amount of force that has occurred. If there is concern for associated injuries, then a more extensive evaluation is mandated with admission for observation.

Acetabular fractures are usually secondary to motor vehicle crashes. The fracture force is either transmitted laterally through the hip or posteriorly through the femur as with a knee-versus-dashboard mechanism. Acetabular fractures are seen commonly with other injuries, including pelvic, femur, and hip fractures and dislocations (Figure 272-11A), and knee injuries. However, these fractures may be subtle and, as a result, necessitate careful inspection on x-ray (Figure 272-11B). If an acetabular fracture is suspected, it can be evaluated with an anteroposterior film, a 45-degree iliac oblique, and a 45-degree obturator oblique view—together known as Judet views. CT is more sensitive than radiography in detecting acetabular injury.²⁰ Also, CT is able to give more detailed information about the displacement of fracture fragments, degree of comminution, and other information that is useful in preoperative planning.

Patients with acetabular fractures require hospital admission and orthopedic consultation. Look for associated visceral, neurovascular, and orthopedic injuries. Sciatic nerve injury is a common complication.

Prevent movement of fracture segments, particularly in the hemodynamically unstable patient. The pelvis can be temporarily yet quickly stabilized with a bed sheet or other pelvic binding device to reduce pelvic volume and stabilize fracture ends.^21,22,23 The simplest technique is the application of either a folded bed sheet secured with towel clips or a commercially manufactured binder that is tightly wrapped around the pelvis at the level of the greater trochanters. A pelvic binder can decrease the volume of the pelvis and, in turn, help diminish blood loss for both open-book and vertical shear fractures. Lateral compression pelvic fractures would not benefit from the application of a pelvic binder because they are already rotated internally; in fact, these patients may be harmed from further lateral compression.²⁴

Provide resuscitation as needed with crystalloid, blood, and blood products. Retroperitoneal bleeding may complicate pelvic fractures. Up to 4 L of blood can be accommodated in the pelvis, until vascular pressure is overcome and tamponade occurs. Most bleeding is due to low-pressure venous bleeding and bleeding from mobile bone edges. Predictors for the need for either a transfusion or a therapeutic intervention due to hemorrhage include: (1) initial hematocrit less than 30%, (2) presence of pelvic hematoma on CT scan, or (3) a systolic blood pressure of less than 90 mm Hg upon arrival.²⁵ Presence of any of these factors mandates close observation of the patient in an intensive care setting.²⁵ Moreover, a recent prospective study showed that base deficit <6 mmol/L or worsening base deficit >2 mmol/L while in the ED also significantly correlated with the need for either angiography or laparotomy.²⁶

FAST, CT, AND PELVIC FRACTURE

In hemodynamically unstable trauma patients with pelvic fractures, carefully evaluate for other sources of blood loss. Patients who have sustained a pelvic fracture from a significant mechanism of injury should undergo a thoraco-abdomino-pelvic CT scan even if the FAST is negative. In the presence of pelvic fracture and serious mechanism blunt trauma, FAST-negative patients are still very likely to have concomitant visceral injury.²⁷

If the FAST examination reveals free intraperitoneal fluid (Figure 272-12), then CT scan is also needed to determine the next treatment step. The FAST false-positive rate for intraperitoneal hemorrhage in patients with pelvic ring disruption can be up to 30%.^28,29 Distortion of the anatomy from fractures, retroperitoneal bleeding, urine from ruptured bladder, or pelvic hematomas may result in fluid collections that mimic free intraperitoneal fluid. The sensitivity and specificity of FAST for free peritoneal blood in major pelvic injury appear to be related to the severity of the pelvic fracture.^28,29

One study reported the overall sensitivity and specificity of FAST to detect free peritoneal fluid in major pelvic injury to be 81% and 87%, respectively.²⁹ The fluid was blood in 76% and urine in 19%.²⁹ Moderate to large free fluid as evidenced by fluid noted in two or more regions of the FAST exam is reported to be associated with the need for hemorrhage control, either by laparotomy or angiography.³⁰

ANGIOGRAPHY, EMBOLIZATION, AND EXTERNAL FIXATION

If a patient with a pelvic fracture is hemodynamically unstable and other sources of bleeding (e.g., splenic or liver laceration) have been excluded through CT scan or laparotomy, treatment options include angiography with embolization, with or without external fixation of the pelvic fracture. Angiographic embolization is effective at controlling arterial bleeding, and external fixation is thought to be effective at controlling venous bleeding.^31,32 Both may be needed to control hemorrhage.

Shock and death are generally due to arterial rather than venous bleeding.^12,13,33,34 Arterial bleeding can occur in all types of pelvic fractures yet does so in only 10% to 15% of cases.³¹ The arteries involved are typically branches of the internal iliac system, with the superior gluteal artery and the obturator artery being the most common (Figure 272-2). Hemorrhage from pelvic fractures refractory to resuscitation is more likely arterial than venous in origin; angiography and embolization can control arterial hemorrhage in most patients.^31,32,33 Consider angiography early in a hemodynamically unstable patient with a pelvic fracture, after other sources of bleeding have been excluded.

Contrast extravasation on CT is considered by many to be an indication for angiography to evaluate for an arterial source of bleeding that may be amenable to embolization.^12,13,32,35 Some protocols advocate angiography based on hemodynamic status, the need for ongoing blood transfusion, or in patients who meet certain blood transfusion amounts.^13,31 No intervention is needed for nearly half of all patients who demonstrate a pelvic blush on CT scan without clinical signs of ongoing bleeding.³⁶ The need for arterial embolization has a positive predictive value of 39% for death in open pelvis fractures, as noted in one recent study.⁴

Another hemorrhage control method used in the treatment of pelvic fractures is extraperitoneal packing. This technique involves surgically placing packing in the pelvis to reduce the potential space needed to tamponade bleeding. Consider this treatment option for an unstable patient who is bleeding secondary to a significant pelvis fracture in a hospital where angiography is not readily available, when a laparotomy is needed prior to angiography, or the patient is in extremis and needs quick stabilization prior to angiography.²⁵

The definitive treatment of pelvic fractures occurs once the patient has been stabilized and after other associated injuries have been addressed. All pelvic fractures require orthopedic consultation and admission, even in the most stable of patients. Elderly patients with simple pubic ramus fractures typically require admission for pain control, observation for complications, and physical therapy for ambulation. The exact treatment of pelvic fractures is guided by fracture location and pelvic stability. Fractures that disrupt the pelvic ring need open reduction and internal fixation within 5 to 14 days of injury.³⁷ The decision as to which service to which to admit the patient will vary between hospitals and depend on multiple factors including the presence of a trauma surgery service, volume of orthopedic cases, comorbidities of the patient, and absence of other significant injuries.³⁸

Acute complications and associated injuries of pelvic fractures include urogynecologic injury, rectal injury, ruptured diaphragm, and nerve root injury. Pelvic fractures can also have long-term effects, including chronic pain, sexual dysfunction, and persistent functional disability.

UROGYNECOLOGIC INJURY

If a urethral injury is suspected clinically, perform retrograde urethrography before placing a Foley catheter. Urinary tract injuries are discussed in greater detail in chapter 265, "Genitourinary Trauma." Gynecologic injuries are uncommon with pelvic trauma. Vaginal laceration can occur with anterior pelvic fractures. Perform a bimanual pelvic examination on women with pelvic fractures. If blood is detected, a speculum examination is needed to identify vaginal hematoma, laceration, or urethral bleeding.

RECTAL INJURY

Rectal injuries are uncommon and are usually associated with urinary injuries and ischial fractures. Diagnosis is by careful rectal examination or by proctoscopy, during which gross blood is found in the rectum. Treatment includes early diverting colostomy with washout of the distal colon and presacral space drainage. Antibiotics that cover gram-negative organisms should be administered as soon as the injury is discovered.

NERVE ROOT INJURY

Nerve root or peripheral nerve injuries can occur because of traction, pressure from hemorrhage, callus or fibrous tissue, and impingement laceration by bone fragments. The onset of symptoms and signs may be delayed, but deficits usually follow a nerve root pattern. Lumbar nerve root injuries are associated with sacroiliac joint dislocation or fracture and longitudinal displacement of the fracture.¹⁴ Sacral root injuries are associated with transverse fractures of S1 and S2 as can be seen secondary to trauma from a suicidal jump (Figure 272-4).¹⁴