Distal Femur Fracture

A distal femur fracture is a break in the lower end of your thigh bone, just above the knee. There are two very different patient groups: young adults whose bone is healthy but who took a high-energy hit (a fall from height, a sports collision, a car accident), and older adults with osteoporosis whose bone is fragile and breaks from a much smaller fall. A growing third group is periprosthetic fractures — breaks just above an existing knee replacement.

You'll have severe pain in your lower thigh and knee immediately after the injury, and you won't be able to put any weight on the leg. The area above and around the knee swells rapidly — often within the first hour — and there may be a visible angular deformity where the thigh looks shortened or bent at an unnatural angle.

Any attempt to move the knee is extremely painful. You may feel grinding or instability when the leg shifts. Bruising around the knee and lower thigh develops over the first 24 to 48 hours. In higher-energy injuries, watch for tight or worsening calf or thigh swelling — numbness, tingling, or pain that seems out of proportion may signal a compartment syndrome and requires immediate medical attention.

Severe knee pain, dramatic swelling, often a visible deformity, and you can't put weight on the leg. Standard knee X-rays from front and side are the primary studies. A CT scan with 3D reconstruction is added when the fracture has shattered into many pieces or extends into the joint surface — those need careful planning before fixation.

Most distal femur fractures that have shifted need surgical fixation — both to put the joint surface back together and to let you start moving the knee and getting up early, which is critical to overall recovery (especially in older patients, where prolonged bed rest carries serious risks of its own).

External patient-education references and related OSI pages for additional background:

• Britannica — Bone disease (fractures)
• Britannica — Knee (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language