Distal Femur Fracture

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Physical Therapy Videos - Femur

Basic Anatomy

The distal femur is the bottom part of your thigh bone. It is a trapezoidal shaped bone that makes up the top of your joint and sits just behind your knee cap. Your knee is the largest weight-bearing joint in the body. The end of the bone is covered with a smooth surface called articular cartilage. This cartilage cushions the knee joint and allows for your knee to bend. Strong muscles in the front of your knee and thigh (quadriceps) and the back of your knee and thigh (hamstrings) allow you to bend and straighten your knee.

X-ray showing the location of the distal femur and a normal knee joint
Figure 1: An x-ray showing the location of the distal femur and a normal knee joint. The knee joint is the area between the green and blue lines.

 

Views of the femur and the distal femur from the front as well as from the side
Figure 2: Views of the femur and the distal femur from the front as well as from the side.

Mechanism and Epidemiology

Fractures of the bottom part of your thigh bone (distal femur fractures) are not common; they make up only about 0.5 percent of all fractures. Since this bone is very strong in younger people, it takes a lot of force to break it (such as a motor vehicle crash), while the weaker bone of an elderly person can break after a ground level fall. Fractures of the distal femur can involve your knee joint.

Fracture of distal femur that does not extend into the knee joint
Figure 3: A fracture of distal femur that does not extend into the knee joint.

 

Fracture of the distal femur that does extend into the knee joint
Figure 4: A fracture of the distal femur that does extend into the knee joint.

Initial Treatment

Distal femur fractures hurt a lot when you try to move your leg or your knee joint. You usually can’t walk on the leg. You may see or feel a bump where the bone is broken, and your injured leg may appear shorter than the other. When you see a doctor, they will take x-rays to see if your bone is broken. A CT scan is often performed as well, to better understand the fracture pattern. Often you will be placed in a knee immobilizer to provide stability for your leg and make it hurt less. People are typically admitted to the hospital for definitive treatment.

General Treatment

Most distal femur fractures are treated with surgery. The broken bone will take a minimum of 2 months to heal. Some can take more than 6 months to heal. Surgery may take place anywhere from 1-5 days after your injury. However, it may be delayed even further if your leg is too swollen or you are not healthy enough for surgery. Rarely, the leg is placed in an "external fixator" (pins drilled into the bone and connected by bars that are outside of your skin) to get your bones lined up, decrease your pain, and let you move around more until your swelling goes down enough for surgery.

Surgery requires incisions on the front, and/or outside and/or inside of your knee and thigh. It may extend along the entire side of your thigh. The bones are realigned and are treated with metal plates and screws or a metal rod placed inside the canal of your bone.

X-rays of a distal femur fracture treated with an intramedullary rod
Figure 5: X-rays of a distal femur fracture treated with an intramedullary rod.

 

X-rays of a patient with a distal femur fracture treated with plates and screws
Figure 6: X-rays of a patient with a distal femur fracture treated with plates and screws.

 

X-rays of a patient with a distal femur fracture 6 months after surgery
Figure 7: X-rays of a patient with a distal femur fracture 6 months after surgery. The patient has healed with abundant extra bone. They had no pain, full motion, and returned to normal activities of daily living.

Postoperative Care

While your broken distal femur is healing, you may not be able to put all or any of your weight on that leg for 6 to 12 weeks. However, some fractures are stable enough for weightbearing right away. Your surgeon will make this decision. Most of the time you can begin to move the knee after surgery. Sometimes a hinged knee brace is placed over your knee. It is important during recovery to work on moving your ankle, as this can become very stiff. Once you begin to bear weight, you may need to use an assistive device such as a walker or cane. Physical therapy may be used to help your recovery. In order as much function of your knee as possible, it is important to follow the instructions you are given by your physician.

Long Term

Your leg will become significantly weaker than the other, unaffected leg while you are recovering and healing. This may take many months to improve. After surgery, you may have numbness around the scar and your leg may be very swollen. The swelling may continue for months or it may never completely go away. The plates and screws can sometimes become bothersome, especially around the outside and the inside of your knee. These may need to be removed after the fracture has healed, and this requires an additional surgery. If the hardware does not bother you, there is usually no reason to have it taken out.

Long-term issues after distal femur fractures can include failure of the fracture to heal. This can cause pain, weakness, and deformity of the knee. If this occurs, it is very important to be evaluated by your treating physician, and likely will require more surgery.

Failure of the plates and screws causing a deformity of the leg
Figure 8: Failure of the plates and screws causing a deformity of the leg.

 

Physical Therapy Videos - Femur

More Information

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Christopher Lee, MD
Edited by the OTA Patient Education Committee and Justin Haller, MD (section lead)
All x-rays and pictures taken from the personal collections of Dr. Lee and Christopher Domes, MD