A closed bilateral femur fracture involves a break in both thigh bones. This injury is “closed” because the skin remains intact, with no open wound exposing the fracture site. Despite the absence of an external wound, a bilateral femur fracture is a severe injury with a substantial risk of internal bleeding into the surrounding tissues.
The Femur’s Vulnerability
The femur’s size and its surrounding anatomical structures make it highly susceptible to significant internal bleeding when fractured. It requires considerable force to break, often indicating a high-energy trauma. The bone itself has a rich blood supply, particularly within its marrow, and is enveloped by major arteries and veins, including the femoral artery and vein. When the femur fractures, these blood vessels are torn and damaged, leading to blood accumulating within the thigh’s muscle compartments and soft tissues. The extensive vascular network means that even a closed fracture can result in a large volume of blood collecting internally.
Estimating Blood Loss
A single closed femur fracture can lead to 1,000 to 1,500 milliliters (1 to 1.5 liters) of internal blood loss. For bilateral femur fractures, this amount can double, potentially reaching 2,000 to 3,000 milliliters (2 to 3 liters) internally. These figures are estimates, and actual blood loss varies based on several factors. A comminuted fracture, with more bone fragments, often causes greater bleeding due to increased soft tissue and vascular disruption; other associated injuries, the extent of soft tissue damage, and individual factors like blood thinner use also influence total blood loss. Given an average adult has about 5 liters of blood, losing 2 to 3 liters is substantial and life-threatening.
The Body’s Response to Severe Blood Loss
Losing a significant amount of blood, such as 2 to 3 liters, triggers physiological responses as the body attempts to compensate for the reduced blood volume, a condition known as hypovolemia. This severe reduction in circulating blood volume can rapidly lead to hypovolemic shock, where the body struggles to pump enough blood to its organs. The initial signs of this response include a rapid heart rate and faster breathing, as the body tries to circulate the remaining blood more efficiently and increase oxygen intake. As blood loss progresses, blood pressure drops, and the skin may become cool and clammy due to the body redirecting blood flow away from the extremities to prioritize vital organs like the brain and heart. Reduced blood flow to the brain can cause confusion, while insufficient blood to the kidneys can lead to decreased urine output; if not addressed promptly, the prolonged lack of oxygen delivery to vital organs can result in organ damage or failure.
Immediate Medical Urgency
Given the potential for substantial blood loss and rapid onset of hypovolemic shock, closed bilateral femur fractures require immediate emergency medical attention; swift intervention is crucial to mitigate life-threatening consequences. Primary goals in pre-hospital and early hospital care are to control ongoing blood loss and restore circulating blood volume. While internal bleeding cannot be directly stopped in the field, fracture stabilization can help minimize further hemorrhage. Restoring blood volume often involves rapid intravenous fluid administration and blood transfusions. Delays in medical care can worsen patient outcomes and increase mortality risk, so the speed and effectiveness of the medical response are essential for survival and preventing irreversible damage.