Distal femur and knee fractures often result from motor vehicle accidents, especially those involving pedestrians or bicyclists. They can also occur as a result of a fall.
The femur is the long thigh bone. Its lower end, or distal femur, flares out the end and joins with the tibia (shin bone) to form the knee joint.
What Types of Fractures Affect the Distal Femur?
The distal femur can fracture in different ways. When the bone breaks straight across, it is called a transverse fracture. If it breaks into many pieces, it is referred to as a comminuted fracture. When the fracture extends into the knee joint and separates the surface of the bone into several parts, this is called an intra-articular fracture, because it involves the articular cartilage, which normally allows the joint to bend and straighten smoothly. Because of the cartilage damage, these fractures are more difficult to treat.
Distal femur fractures can be closed or open. If the bone fragments are sticking out through the skin, it is an open fracture. Open fractures are likely to involve more damage to the muscles, tendons, and ligaments that support the knee and therefore take a longer time to heal. They also have a higher risk for complications.
When the distal femur breaks, the muscles of the thigh—the hamstrings and quadriceps muscles—often shorten and contract, causing the bone fragments to change position, making it difficult to align the fragments with a cast.
Nonsurgical Treatment Options
Traction and casting and braces are nonsurgical treatments for distal femur fractures. But fractures heal better and certain complications can be avoided if the patient is able to get up and move around. This isn’t possible with traction, in which a system of pulleys and weights hold the pieces of bone in place, using a pin in a bone to position the leg.
Casting and braces can be used to hold the bone in place, but only in a stable fracture limited to two parts and able to be aligned correctly with a brace.
Surgery Is Often the Best Way to Go
In most cases, surgery provides a better outcome. With soft tissue damage, the doctor will sometimes apply a temporary external fixator first, which is a frame to stabilize the fracture and hold the bones in position until the patient is ready for surgery.
When the soft tissue damage has resolved, the doctor will schedule internal fixation surgery. Surgery is followed by a course of physical therapy.
A distal femur fracture requires a year or more of treatment. Possible complications are infection, poor healing, stiffness, and arthritis. Sometimes it will be necessary to do a bone graft, or a total knee replacement.
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