Consultant Teachings No. 5: Pelvic Ring and Acetabular Injuries for the Emergency Provider

Case Scenario: A 33 year-old female falls from a second story balcony and has immediate pelvic pain.  She is unable to ambulate. Per EMS, she had transient hypotension to a blood pressure of 80/60 en route that responded to a 1L crystalloid bolus. In the trauma bay, she is mildly tachycardic (HR 110), normotensive (117/70), and is mentating appropriately. She is neurovascularly intact and has a pelvic binder is in place. What do you do next?


Pelvic ring and acetabular injuries can affect all age groups and encompass a wide variety of clinical presentations.  An understanding of injury mechanism and basic pelvic and acetabular anatomy is critical to appropriate patient management.

As a starting point, the important points of physical exam of any pelvic fracture patient (as incorporated in the primary and secondary survey of ATLS) include:

1. Careful neurovascular assessment of both lower extremities.

2. Skin inspection to rule out open wounds.

3. Inspection of the flank or perineum for contusions or ecchymoses.

4. Evidence of urogenital injuries like scrotal edema, blood at the urethral meatus or vaginal canal.

5. Rectal exam to rule out open communication of the rectal mucosa with the fracture site.

Pelvic fractures are a marker of a significant force applied to the human body; in addition to bleeding due to the pelvic fracture, hemorrhagic shock in this patient population is often due to hemorrhage from other injuries (chest 15%, intrabdominal 32%, long bones 40%) [1].   Thus, management of hemorrhagic shock in a patient with an obvious pelvic fracture involves a thorough assessment for extra-pelvic sources of hemorrhage, as concomitant head, chest or abdominal injuries contribute to the persistently high mortality rates.

Fracture Patterns

Familiarity with basic pelvic injury patterns is important to the initial management of the pelvic injury itself as well as the assessment of likelihood of associated injuries. There are three basic injury patterns to the pelvic ring that you should be aware of as an emergency provider: anterior-posterior compression, lateral compression, and vertical shear [2]. 

Although knowing the injury mechanism may help, the best way to initially discern between these injuries is with an AP pelvis X-ray. To make it easy, for pelvic ring injuries, just look at 3 areas:

1. The pubic symphysis

2. The SI joint/sacrum.

3. The pubic rami


Anterior Posterior Compression (APC) (“open book”):  look for widening of the symphysis +/- widening of the sacroiliac joint

These are dominant form of pelvic disruption in crush injuries, pedestrians struck and motorcycle accidents [3].  APC injuries carry with them the highest mortality risk due to:

-    a high rate of circulatory shock due to pelvic vascular injury and development of retroperitoneal hematomas.

-    greatest overall transfusion requirements

-    higher incidence of intra-abdominal injuries (8x incidence of thoracic aorta injuries compared to blunt trauma without pelvic injury), spine and extremity fracture. [4]

-    increased risk of developing ARDS, in part due to early resuscitative requirements.


Lateral Compression (LC): look for rami fractures +/- sacral fractures

These are most commonly associated with high speed motor vehicle accidents involving lateral impact [3].

-    higher incidence of intra-cranial injuries (50%) likely due to association with high speed MVA.  Brain injury is the most likely cause of death in this patient population.

-    high incidence of concomitant lower extremity fractures and retroperitoneal hematoma

-    generally, stable LC injuries are not associated with major pelvic vascular injury


Vertical Shear : look for vertical displacement of the hemipelvis (again, look at the relative position of each pubis at the PS, the relative position of the inferior part of the SI joint on each side; you can also consider the relative position of the hip joints, and the relative position of the iliac crests).

Along with acetabular fractures, this is most commonly seen in fall victims [3].

- high risk of hypovolemic shock, overall mortality and head injury.


To bind, or not to bind… that is the question.

The primary source of hemorrhage from pelvic fractures is due to bleeding from the cancellous bone surfaces or the posterior pelvic venous plexus [5].    Only in 10-15% of cases is the patient bleeding from an arterial source, usually from branches of the internal iliac system [5].

Whether to place a external binder is actually a more loaded question than meets the eye.  To start, pelvic binders are intended to assist with resuscitation of hemodynamically unstable patients with volume expanding pelvic ring injuries by decreasing the pelvic volume and splinting (stabilizing) the pelvis to avoid clot disruption.    The placement of a pelvic binder decreases the volume of the pelvis by 10 – 20% and reduces pelvic fractures.  This reduction in pelvic volume has not yet been shown to lead to less blood loss or improved outcome, but the 2011 East Guidelines still recommend the practice in hemodynamically unstable patients as a Level III recommendation [5].  There is little utility in binder application in the patient who is hemodynamically stable (although, it may provide some comfort by stabilizing the fracture or dislocation).

Furthermore, not all fractures may benefit from pelvic binding.  While APC injury patterns in the hemodynamically unstable patient benefit from pelvic binding, LC injuries may worsen with pelvic binding as this recreates the original deforming force.  This could cause an over-reduction of the pelvis and theoretically put the bladder at risk for injury (although this has not been reported). VS injury patterns most often benefit from skeletal traction, but occasionally benefit from a combination of traction and pelvic binding depending on the injury.  Binders do carry their own morbidity (pressure ulcers, etc.).  If the decision is made to place a pelvic binder, it should be placed over the greater trochanters with the patient’s lower extremities in adduction and internal rotation

Depending on the patient, your orthopedic consultant may ask that the binder be released for the purpose of obtaining an unreduced injury film. Ideally, an AP Pelvis should be taken immediately after the Chest AP, prior to the placement of a binder, if possible. This allows for a more accurate assessment of the pelvic injury by both the emergency department team and the orthopaedic consultant. If a patient comes in with a pelvic binder placed by EMS or an outside hospital, the decision to remove the binder has to be taken on a case-by-case basis depending on patient stability.   An unbounded AP pelvis can be obtained later in a more optimal setting such as the OR or ICU. As you can see below, an AP pelvis view with a binder can underestimate the degree of displacement and injury severity. 


Of note, in a stable patient, complete radiographic evaluation of the pelvic ring injury includes an Inlet and Outlet view following review and diagnosis of a pelvic ring injury on the AP view.


A word on acetabular fractures

Image Source:

Although fractures of the acetabulum can also occur with a high-energy injury mechanism, it is important to understand that these are very different entities than pelvic ring injuries. In a high-energy setting (much different than low-energy geriatric falls with acetabular fractures) there is still a high incidence of associated extremity and visceral injuries. One study found concomitant lower extremity injuries in 36% of patients [6]. Fractures involving the femur or knee are common and are important to include in your radiographic evaluation in this setting. Certain fracture patterns (eg. Both column or T-type) about the acetabulum represent even more high-energy trauma than others. Additionally, these fracture patterns may expose a larger amount of cancellous bleeding surface and demonstrate a greater degree of displacement.  Patients with isolated acetabular fractures may have transfusion requirements that are directly related to these factors. One study looking specifically at isolated pelvic ring and acetabular trauma noted that patients are just as likely to have transfusion requirements during the first 24 hours after admission to the trauma center [7]. However, as stated for pelvic ring injuries – these fractures should not distract from aggressively searching for alternative sources of visceral or extremity bleeding.

The radiographic evaluation of acetabular injuries should not be confused with the pelvic ring injuries, as described above (SI joint, pubic rami, and symphysis). The radiographic lines that are evaluated in acetabular injuries are the anterior wall (orange), posterior wall (green), dome (yellow), tear drop (brown), anterior column (blue) and posterior column (red). For the Emergency provider, mastering the interpretations of these radiographic lines is less important than recognizing acetabular fractures as a broad category. It is also important to maintain a high index of suspicion for acetabular fractures associated with hip dislocations, as these injuries require prompt reduction to minimize the risk of femoral head AVN. Also of note, acetabular fractures are not amenable to pelvic binder placement. They serve no purpose in this setting. These injuries are best radiographically evaluated with an AP pelvis and Judet views. CT imaging remains an important part of the evaluation of both pelvic ring and acetabular injuries. 


Submitted by Christopher Cosgrove, Orthopedic Surgery PGY-2

Faculty Reviewed by Christopher McAndrew, Orthopedic Trauma

Everyday EBM Editor : Maia Dorsett (@maiadorsett)


Take home points:

-    An AP pelvis is strongly encouraged in the initial evaluation, prior to the placement of external binders.

-    Make an effort to evaluate the locations of fractures and assess the injury pattern on the AP pelvis X-ray as part of the initial radiographic assessment. This pattern recognition can help you focus your assessment of common associated injuries as well as direct your resuscitation management.

-    Acetabular fractures require a separate radiographic evaluation than pelvic ring injuries.   They are not amenable to binder placement. Differentiate these from a pelvic ring injury during your initial evaluation.



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