Emergency Stabilization of Unstable Pelvic Fractures

Patients with unstable pelvic fractures from high-energy mechanisms like pedestrian versus motor vehicle or a fall from a great height are at high risk of fatality from major blood loss. Understanding the anatomy of the pelvis and surrounding structures and the types of pelvic fractures that can occur can help EMS providers recognize and provide in-field stabilization of a pelvic fracture. There are several methods to stabilize a fractured pelvis, but all share the goal of stabilization and reduction.1

Anatomy and Function

The function of the pelvis is to bear weight. The weight of the upper body is borne by the pelvis and distributed to the legs when a person is standing or to the ischium when a person is sitting. The pelvis also protects major blood vessels and organs in the lower abdominal cavity, including parts of the digestive, urinary and reproductive systems. The pelvis is the attachment point for numerous muscles that connect the legs to the body. The actions of walking, running, standing and many other functions involve movement of an intact and stable pelvis.2

The pelvis is a ring of paired bones that is the attachment point between the upper and lower skeleton. The pelvic ring is formed by pairs of fused bones. The pelvis includes the sacral section of the spinal cord in the posterior. Attached to each side of the sacrum is an ilium, the top of which is known as the iliac crest. On the anterior portion of the pelvis are the pubis and the ischium. The two pubis bones are connected by the symphysis pubis.3

Many organs and blood vessels pass through or near the bones of the pelvis, including the bladder, urethra, end of the large intestine and internal reproductive organs.4,5 Large blood vessels located in the pelvic ring can be the source of severe bleeding, and large amounts of blood from uncontrolled hemorrhage can accumulate in the free space around the pelvis. The right and left iliac arteries descending from the aorta are located in the pelvis. Blood returns from the lower extremities via the right and left iliac veins. Major blood vessels also supply the tissue, bones and organs in the pelvic ring. Blood loss can also originate from bony fracture surfaces and surrounding soft tissue injuries. Uncontrolled bleeding is the leading cause of death for patients with a complex pelvic fracture.

Mechanisms of Injury

Primary mechanisms of injury for pelvic fracture often involve large amounts of energy and/or mass. A motor-vehicle collision, motorcycle crash or even a downhill skiing accident are examples of high-force and high-speed collisions. Pelvic fractures are reported to be the third leading cause of mortality from motor-vehicle collisions. Falls from height, such as a construction worker falling from a roof or a rock climber falling from a cliff, may result in pelvic fracture. Crushing injuries can also apply sufficient force to the body to cause a pelvic fracture.

Pelvic ring fractures can be caused by different types of forces, such as lateral or anteroposterior compression and vertical shear forcing. Vertical shearing is likely from a fall; lateral compression is the most common type of force that can cause a pelvic fracture, since force is applied to the body from the side, as in a side-impact motor-vehicle accident.

With anteroposterior compression, force is applied from front to back, which is typical in a head-on motor-vehicle collision.

An iliac crest fracture, which is a fracture to the upper wing of the ilium, may present with localized pain, tenderness and bruising, but it is a relatively stable injury that is less likely to threaten adjacent organs or blood vessels. While this might be painful and show instability during a physical exam, the pelvic ring is intact. This type of pelvic fracture is isolated and stable, and the life threat is low.