Description
The thighbone, or the femur, is the largest bone in the body. The top of the femur connects to the pelvis and together they form the hip. The bottom of the femur connects to the tibia and fibula, or shinbones, and together they form the knee. Femur fractures can occur through the growth plate close to the knee, which is made of cartilage, because the cartilage is weaker than the bone.
Diagram of femur, with arrows pointing at hip joint and knee joint. The shaft region of the bone is shaded
Types of fractures
Hip fractures:
The hip joint is made up of the connection of the pelvis to the femur. When the femur is broken at the top part, this is considered a hip fracture.
Femoral shaft fractures:
These occur in the middle of the femur where the walls of the bone are thick. This information sheet refers to this type of fracture.
Distal femur (knee) fractures:
These femur fractures occur near the knee, and are often near or through the growth plate.
Stress fractures:
Stress fractures occur over time without injury. They can happen due to overuse, or a sudden increase in exercise.
Symptoms
A crooked thigh, swelling, bruising, and pain are the most obvious signs that the bone is broken. The child will not be able to walk and usually cannot move their leg. In toddlers and young children, femur fractures sometimes occur after a ground level fall, leg hyperextension or twisting injuries. Child abuse is another common cause of femur fractures in infants and young children. In older children and adolescents, a femur fracture usually requires a high-energy injury, such as a car crash, contact sports, or fall from height.
Examination
The doctor will carefully look at the skin around the leg as well as touch different areas to see what hurts. He or she may also try to gently move the joints. The doctor will also test the nerves and circulation to the foot.
Other Tests
Most of the time, x-rays are all that is needed to diagnose a femur fracture. X-rays will include the top of the femur (hip and pelvis) and the knee, as doctors want to see the joint above and below the injury. Sometimes breaks of the femur near the growth plate are hard to see on x-rays. Your doctor may choose to “stress” the leg by pulling on it in the x-ray, to further evaluate for this injury.
Treatment
Femur fractures are treated based on the location of the break and the age of the child. In children younger than 6 months, most femur fractures are treated in a Pavlik Harness. This is a soft harness that holds the baby’s leg still. The bones in this age group have the ability to heal, reshape, and remodel to an amazing extent. From 6 months to 4 years of age, most femur fractures are treated by setting the bone (manipulating) and placing a body cast. Fractures that are around the knee are treated with a long leg cast, and fractures of the midportion and upper end of the femur are treated with a body cast (hip spica cast). Fractures that are treated in a cast usually do not heal straight and “end on end”. This is OK because the bone can grow straight over time with normal leg function.
Figures: (a) displaced injury films, (b) healed fracture with overlap and angulation, (c) remodeled x-ray 10 months later
(a) 
(b) 
(c) 
In younger children, surgery may be needed in some circumstances:
- There is a cut in the skin near the broken bone
- The bones will not stay lined up even in a cast
- The bones have started to heal in a bad position
In older children and adolescents, surgery is chosen to align the bone with metal implants. Different types of implants may be used in surgery to keep the bones aligned. This may include flexible nails (rods), rigid nails (rods) or even plates and screws. Children and teenagers who are still growing should not get the same rods that adults would get. The placement of adult rods can risk damaging the blood supply to the top of the femur bone and cause long-term problems with the hip joint.
After surgery, a cast or splint may still be used to protect the bones in place during healing.
Figures: 5 year old children with a femur fracture treated with flexible rods (a) after initial surgery (b) healing at 8 weeks; (c) complete healing at 5 months.
(a) 
(b) 
(c) 
Outcomes
Children usually recover from their femur fractures within a few months. If necessary, your doctor may watch your child for a few years to be sure that their bones grow straight. Growth plate fractures at the knee are more likely to cause long-term growth problems than in other parts of the body. Your doctor may also want check that the child’s leg lengths because some femur fractures can heal short and some can grow longer than the other leg during the healing process. Most growing children will not require physical therapy but may need pins or flexible nails removed to regain full motion.
Children are not just small adults and need expert care. The Pediatric Orthopaedic surgeon should be involved in the care of femur fractures in children due to increased risks of treatment to the growing child.