Leg Fracture

What Is It?

Whenever a bone breaks or cracks, the injury is called a fracture. In the leg, fractures can occur almost anywhere along the straight shafts of the leg's three long bones — the femur (the thighbone) or the tibia and fibula in the lower leg. When a fracture's crack or break involves the knobby end portions of these bones that are part of the hip, knee and ankle joints, the fracture creates additional concerns. For the sake of simplicity, this article describes only fractures of the shafts of the three long leg bones.

Femoral Shaft Fractures
The femur is very strong, so it takes a large amount of force to fracture this bone in healthy people. Femur fractures generally occur in people who have suffered high-impact trauma, especially in automobile accidents, industrial accidents, falls from high places, or gunshot wounds to the thigh. If a femur fracture follows a low-impact bump or fall, this may be a sign that the femur has been weakened by an illness such as osteoporosis or cancer.

Femur fractures have the potential to cause dangerous, sometimes life-threatening complications, such as significant bleeding inside the thigh, with blood loss of one quart or more. A femur fracture also may trigger the formation of blood clots within the large veins of the thigh. If these clots break free and travel through the bloodstream, they eventually can lodge in the lungs, creating a life-threatening condition called a pulmonary embolism.

Femur fractures occur in about three out of every 10,000 people in the United States each year. Among children, these fractures tend to happen because of a fall from a high place, such as a tree or the top of a slide. In adults, these injuries usually are related to motor vehicle accidents (either as a passenger or pedestrian) or to on-the-job trauma. There has been a significant rise in the number of femur fractures caused by gunshot wounds in recent years.

Tibial Shaft Fractures
The tibia (shinbone) is the larger of the two bones of the lower leg. Like femur fractures, tibia fractures often occur because of direct, high-impact trauma, especially during motor vehicle accidents. However, they also can result from a low impact, even in healthy people, if the lower leg is bent or twisted at just the right angle.

Of all the body's long bones, the tibia is not only the most likely to be fractured, but it is also the most likely to break through the skin when it fractures. This greatly increases the risk of bacterial contamination and infection at the fracture site. It also may prevent normal healing. The sharp ends of a broken tibia can cut into nearby nerves and blood vessels, and cause serious damage to soft tissues inside the lower leg.

In 75 percent to 85 percent of patients with tibia fractures, the fibula (the thin bone at the outer side of the lower leg) is fractured as well. Doctors treat more than 185,000 lower leg fractures in the United States every year, including both tibia fractures and fibula fractures.