Broken Femur (Thigh Bone)

What is a broken femur?

A broken femur (thigh bone) is a break in your child’s longest, largest, heaviest, and strongest bone. The femur makes normal standing and walking possible. Although it’s a difficult bone to break, femur fractures in childhood are not uncommon.

Because of the femur’s great strength and size, fractures tend to occur only when the bone is hit with a very strong force. Femur fractures are serious injuries but most can heal without surgical treatment.

What differentiates the femur from the other bones in a child’s leg?

The leg extends from the pelvis to the knee (thigh) and from the knee to the ankle (lower leg). The leg has three long bones — the femur, tibia, and fibula — as well as a fourth bone, the patella, also known as the kneecap. 

This is the lower extremity anatomy of the leg,

What are the different types of fractures?

One way to classify fractures in the femur is by the location of the break. A femur fracture can occur at several places in this long bone, including:

  • Proximal femur fracture (hip fracture): A break in the uppermost part of thigh bone next to the hip joint.
  • Femoral shaft fracture: A break in the bone shaft. This type of fracture is very serious and almost always requires surgical correction.
  • Supracondylar femur fracture: A break just above the knee joint. This type of fracture is an uncommon break, especially in children.
  • Distal femur fracture: A break in the top part of the knee joint. A distal femur fracture can extend into the knee joint and disturb knee cartilage and growth plates. If the bone pierces through the skin (open fracture) there is a high chance that there will be damage to the muscles, tendons, and ligaments.

Learn more about common fractures in children

What causes broken femurs?

A bone break happens when there’s more force applied to the bone than it can absorb. These breaks in bones can occur from falls, trauma, or a direct blow.

Most childhood fractures result from:

  • falling, as from stairs or jungle gym
  • trauma (moderate to severe) that may happen in a car accident or while they’re participating in contact sports

Femur fractures in infants (0-1 year old) are unusual, but can occur:

  • in babies born with a condition that causes weak bones, such as osteogenesis imperfecta
  • following a very difficult delivery
  • in cases of child abuse

Certain risk factors may also increase a child’s chances of breaking a femur. 

The signs and symptoms of a broken femur in children include:

  • pain or swelling in the thigh, possibly with bruising
  • difficulty moving the leg
  • inability to stand or walk
  • deformity (abnormal shape) of the leg
  • in severe fractures, the bone may come through the skin and be visible