What are the tibia and fibula?

tibia and fibula

Image source: Wikimedia Commons

The tibia and fibula are two bones that run in parallel through the lower part of the human leg. The two bones are connected to each other by the interosseous membrane; they form a type of joint called a syndesmosis, a fibrous joint that can move slightly but is not designed to bend.

The tibia, sometimes referred to as the “shankbone” or “shinbone,” is stronger and larger than the fibula. It is the second largest bone in the human body, running from the knee to the ankle. The tibia absorbs most of the weight of the human body as a person walks, runs, and jumps.

The fibula is the smaller of the two bones and is not designed to carry as much weight as the tibia. Its main purpose is to stabilize the tibia.

How can these bones break?

While it is strong, the tibia is still one of the most commonly broken bones in the human body. The fibula can help brace the tibia, but one or both can easily break due to a car accident, fall, sports accident, motorcycle accident, bicycle accident, or the repetitive stress of a weight-bearing sport.

The patterns of breakage may be different depending on the forces involved in an injury. Low forces may produce a stable fracture, in which the bone is cracked but not out of place. In a displaced fracture, the two ends of the broken bone are separated from each other. A very severe type of injury is a communited fracture, in which the bone is shattered into three or more pieces. Communited fractures can occur after crushing injuries or very high-speed collisions.

A fracture is called open or compound when a shard of broken bone protrudes through the skin. These types of fractures can be particularly dangerous; in addition to tearing through the delicate skin, muscle, and other soft tissues, they can spread infections that would normally not be able to penetrate so deep into the body. When a fracture is closed, the bone does not break the skin, although it may still tear through surrounding tissue including muscles and blood vessels. In severe fractures, a patient may be able to see the edges of a broken bone “tenting” the skin that covers the break.

A transverse fracture happens when the bone is broken straight across and displaced, while an oblique fracture happens when the bone breaks at an angle. An oblique fracture may start out as stable, but become displaced over time if the break is not treated immediately. A spiral fracture occurs when the bone is twisted, causing a spiral-shaped crack around the column of the bone.

How can a tibia or fibula fracture be treated?

If you suspect that you have fractured one or both of these bones, seek medical attention immediately. A stable fracture can be displaced over time if it goes untreated, leading to a longer healing process and possibly permanent damage. In the most extreme cases, a disrupted blood supply that goes untreated could make amputation a necessity, or an infection could lead to organ damage or even death.

The first step in treating a tibia or fibia fracture is usually getting an image of the bone. A doctor may begin with an x-ray to see the bone itself and diagnose the exact type of fracture. A computed tomography (CT) scan may also be necessary if your doctor is concerned about a fracture that could extend into the ankle or knee joint.

In severe cases, surgical treatment may be needed to draw the two or more fragmented ends of the bone together and keep them in place so they can heal. Intramedullary nails are long metal rods that go through the bone to keep it stable as it heals. Plates and screws can be used in cases where intramedullary nailing is not possible because a fracture extends into other joints. External fixation, in which internal pins or screws secure a metal rod outside the skin, may be used in certain cases but is unpopular with patients and doctors and can heighten the risk of infection.

In cases where the bone is shattered into many small pieces, additional surgeries may be necessary to remove bone fragments. Some patients who are allergic to metal, or whose metal hardware is improperly placed, may need to undergo additional surgeries to remove this hardware after the bone is stabilized.

Nonsurgical treatments may be available for patients with less severe fractures. These usually involve immobilizing the leg in a cast as it completes the initial phases of healing, then transitioning to a functional brace that allows some movement but still provides stability. In some cases, a surgeon may decide not to operate on a patient with a more severe fracture if their overall health would make surgery particularly risky for them.

How long will it take to heal from a tibia or fibula fracture?

Each patient’s case is different, and your doctor will be your best source of information on how long you should expect the recovery process to take. Some fractures may take 6 months or longer to heal fully, and after a severe fracture, a patient may feel some pain or weakness many months or even years after the initial injury. Some conditions like the use of certain steroids or tobacco products may slow the healing of skin and bones.

Many doctors will encourage their patients to be as active as possible early in the recovery period so that the soft tissues of the toes, foot, ankle and knee do not become too stiff. Some will write a prescription for physical therapy; a physical therapist or physiatrist can monitor a recovering patient’s progress and help them work on building up muscle strength.

Sources:

 "Arnold's Glossary of Anatomy." Anatomy Glossary. N.p., n.d. Web. 10 June 2016. 

 "Tibia (Shinbone) Shaft Fractures-OrthoInfo - AAOS." Tibia (Shinbone) Shaft Fractures-OrthoInfo - AAOS. N.p., n.d. Web. 10 June 2016.