A broken pelvis, or pelvic fracture, is an injury to the bony ring connecting the spine to the legs. This trauma usually results from high-energy events like motor vehicle accidents or falls from significant heights. A broken pelvis can lead to death, but fatality is typically not a direct result of the bone breaking itself. Instead, death arises from severe complications caused by the fracture and the initial trauma. The high forces required to fracture the pelvis often cause other major injuries, which collectively contribute to a highly unstable medical situation requiring immediate, specialized treatment.
Understanding the Mortality Rate
The risk of death following a pelvic fracture is highly variable and correlates directly with the force involved in the injury. Low-impact fractures, such as a simple break from a fall, carry a very low risk of mortality. Fractures resulting from high-energy trauma, like a car crash, can have a cumulative mortality rate ranging from 10% to 30%.
For the most severe, unstable pelvic fractures, the mortality rate can climb significantly higher. When a patient arrives in hemorrhagic shock, the risk is even more pronounced, reflecting the overall severity of multiple injuries sustained in the high-energy event.
A majority of patients who do not survive an unstable pelvic fracture die within the first 24 to 48 hours after the trauma. The leading cause of early death is massive bleeding. Deaths occurring later are often attributed to complications such as sepsis or multi-organ failure, which are systemic responses to the initial trauma and blood loss.
The Primary Cause of Death: Internal Hemorrhage
The most immediate and life-threatening complication of a severe pelvic fracture is massive internal hemorrhage. The pelvis houses a rich network of blood vessels, including major arteries and an extensive venous plexus. When the bony ring shatters, sharp fragments can tear these vessels, leading to rapid and uncontrolled blood loss.
Bleeding from the veins and bone surfaces accounts for the majority of blood loss. Arterial bleeding, while less common, is often more difficult to stop and contributes significantly to the most unstable cases. The pelvis is surrounded by the retroperitoneal space, a region that can hold several liters of blood without external swelling, masking the severity of the injury.
This massive internal blood loss quickly leads to hypovolemic shock, where the body lacks sufficient blood volume to circulate oxygen to vital organs. As blood pressure drops severely, organ systems begin to shut down. The lack of a natural “tamponade” effect is lost when the pelvic ring is disrupted, allowing bleeding to continue into the open space.
Distinguishing Stable and Unstable Pelvic Fractures
The distinction between stable and unstable fractures is crucial for determining risk. A stable pelvic fracture typically involves only one break point in the bony ring, such as an isolated fracture of the pubic ramus. These are usually low-impact injuries where the pelvic ring remains intact and does not significantly displace, maintaining the internal volume of the pelvis.
An unstable pelvic fracture involves multiple breaks and displacement, signifying a complete disruption of the pelvic ring. These fractures are almost exclusively the result of high-energy trauma and are classified using systems like Young-Burgess or Tile. The mechanical instability allows the two halves of the pelvis to separate, dramatically increasing the internal volume of the cavity. This increased space makes it difficult for the body to clot the blood, leading to continuous hemorrhage.
The degree of displacement in an unstable fracture is directly linked to the severity of associated vascular damage. Fractures allowing severe rotation or vertical shifting are most associated with major bleeding because they stretch and tear surrounding blood vessels and ligaments.
Immediate Medical Stabilization and Treatment
The immediate focus in treating a severe pelvic fracture is rapid stabilization to control internal hemorrhage. The first non-invasive step is applying a pelvic binder—a specialized belt wrapped tightly around the hips. This external compression temporarily “closes” the fracture, mechanically reducing pelvic volume and slowing bleeding by providing a temporary tamponade effect.
Once stabilized, the trauma team works to achieve definitive hemorrhage control and mechanical stability. For continued arterial bleeding, angiography with embolization may be performed. This involves threading a catheter to the bleeding site and injecting material to intentionally block the damaged vessel, stopping blood flow.
Another immediate surgical intervention is external fixation, where metal pins are drilled into the bones and connected to an external frame. This frame provides rigid stability, helping to maintain reduced pelvic volume and prevent further vessel damage. These emergency procedures are paramount for stopping blood loss and preventing death from hypovolemic shock.