Knee Fractures

There are four bones that make up the knee joint: the thigh bone, the two leg bones, and the kneecap. The thigh bone is called the femur and is a weight-bearing bone of the knee.

The leg bone that bears all the weight is called the tibia. The fibula is the other leg bone and provides an attachment site for muscles and ligaments. The patella is the kneecap, which is an important part of the mechanism that extends or straightens the knee. A knee fracture can involve any one or more of these four bones.

Before we get into the names of knee fractures, there are many words that are used to describe the way a bone has fractured that can be used to describe fractures anywhere in the body; however, they apply to knee fractures as well.

The way that a bone is fractured is important when considering what treatment will be required for a good recovery. The key word for determining what treatment a fracture may need is “stability.” Ultimately, if a fracture is not stable, it may require surgery to keep it stable while it heals.

Some words used to describe fractures are:

• Stable fracture: When the broken bone remains in place and does not move out of position. This type of fracture may not require surgery. If a fracture is either stable on its own or can be made stable without surgery, non-operative treatment—such as a cast or brace—may be all that is required to allow the bone to heal properly.
• Unstable fracture: When the broken bone is broken in such a way that it no longer functions to provide stability or contribute to its normal function in the knee joint. Unstable fractures usually require a procedure such as surgery or “setting of the bone,” which is called a closed reduction to put them in a position to maintain their function after they heal.
• Displaced fracture: When the bone breaks and moves out of its normal position. Displaced fractures are often unstable fractures.This can cause significant pain and instability in the knee joint and often requires surgery for treatment.
• Comminuted fracture: This type of fracture occurs when the bone is shattered into multiple pieces. Comminuted fractures are often unstable and require surgery for treatment.
• Transverse fracture: A type of knee fracture that occurs when the bone breaks horizontally across the knee joint. This type of fracture can be caused by a sudden impact, such as a fall or a direct blow to the knee, and may or may not require surgery depending on whether or not the knee fracture is stable.
• Intra-articular fracture: When the bone is broken in such a way that the fracture involves the cartilage inside the knee joint. Intra-articular fractures are often unstable and often require surgery with some exceptions.
• Open fracture: When the broken bone breaks through the skin, creating an open wound. Open fractures should generally be treated with surgery with few exceptions.

Knee fractures involving the femur are usually distal femur fractures or fractures of the femur right above the knee joint. These are typically described by their location, and what part of the bone is involved.

Fractures just above the weight-bearing portion of the knee joint are called “supracondylar” femur fractures. Fractures of the femur that are higher on the bone are called “distal-third” femur fractures, or “distal femoral shaft” fractures, or even just “distal femur” fractures.

Some distal femur fractures involve the cartilage inside the joint and would then be called “intra-articular distal femur fractures.” Unstable or intra-articular femur fractures generally require surgery for treatment.

Knee fractures involving the kneecap, or the patella, are called patella fractures. Most patella fractures are intra-articular and involve the cartilage on the deep surface of the kneecap.

The main things that determine the treatment for a patella fracture is whether or not the fracture threatens the patient’s ability to straighten the knee, or whether or not the fracture is displaced. Displaced patella fractures, or fractures that disrupt knee extension often require surgery.

Knee fractures that involve the weight bearing leg bone, or the tibia, are usually either intra-articular tibia fractures that involve the bearing surface or the cartilage in the knee called “tibial plateau fractures.” Most tibial plateau fractures are unstable fractures and require surgery for treatment, but not all of them.

Fractures of the tibia bone just below the knee joint are called “proximal tibia fractures,” or proximal tibia shaft fractures.” Proximal tibia fractures are often unstable and often require surgery to treat them.

Knee fractures can also involve the smaller leg bone or the fibula. Sometimes, when the tibia is fractured, the fibula is also fractured along with it. Fibula fractures can happen on their own as well but are often treated without surgery.

The main things that determine what treatment is necessary for the fibula are whether or not the knee is stable despite the fracture. Some fibula fractures require surgery while many can be treated without surgery.