Distal Femur Fracture (Knee End of Thighbone)

Description

This is a break at the lower end of the femur (thighbone), near the knee. It often involves the growth plate there — an especially important one, because it produces a large share of the leg’s length and helps keep the knee straight.

How it happens (the mechanism)

A significant force near the knee — a fall, a sports injury, or a collision — breaks the lower femur, often along or through its growth plate. That growth plate is one of the most productive in the body, which is exactly why this fracture is treated and followed with extra care: lining up the growth plate and joint surface well protects both straight growth and a smooth knee.

What matters

Because this growth plate contributes so much to the leg’s length and alignment, a small number can grow unevenly after an injury here. That is why these are followed more closely and for longer — sometimes until a child finishes growing — so any growth difference is caught early, while it is still simple to manage. The longer follow-up is a safeguard, not a sign something is wrong.

Symptoms

Pain, swelling, and tenderness at the lower thigh and knee, with reluctance to bear weight or bend the knee.

Doctor examination and imaging

The doctor checks alignment and the circulation and feeling of the leg and foot. X-rays show the fracture; sometimes additional views or a CT are used to judge joint or growth-plate involvement.

Treatment

A well-aligned fracture may be treated in a cast. A shifted fracture, especially one crossing the growth plate or joint, is usually realigned and held with pins or screws for precise healing.

Recovery and long-term outlook

Most heal well. The careful alignment and the longer follow-up are what protect growth and knee motion over time.

When to call the doctor

Call the office right away if your child’s toes become numb, pale, blue, or cold; pain keeps worsening even after raising the leg and giving medicine; swelling does not improve with elevation; the cast feels too tight, cracked, or wet, or smells bad; or your child develops a fever.

Learn more

OrthoInfo (AAOS) — Thighbone (Femur) Fractures in Children: orthoinfo.aaos.org

OrthoInfo (AAOS) — Growth Plate Fractures: orthoinfo.aaos.org

This information is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. For specific concerns about your child, consult a board-certified, fellowship-trained pediatric orthopaedic surgeon.