The thighbone (femur) is the strongest bone in the body. It is usually obvious when the thighbone is broken because it takes so much force to break. But a break in the shinbone (tibia) or in the bone that runs alongside the shinbone (fibula) may be less obvious.

Signs and symptoms of a broken leg may include:

• Severe pain, which may worsen with movement
• Swelling
• Tenderness
• Bruising
• Obvious deformity or shortening of the affected leg
• Inability to walk

Toddlers or young children who break a leg may start limping or simply stop walking, even if they can't explain why.

When to see a doctor

If you or your child has any signs or symptoms of a broken leg, seek care right away. Delays in diagnosis and treatment can result in problems later, including poor healing.

Seek emergency medical attention for any leg fracture from a high-impact trauma, such as a car or motorcycle accident. Fractures of the thighbone are severe, potentially life-threatening injuries that require emergency medical services to help protect the area from further damage and to provide safe transfer to a local hospital.

A broken leg can be caused by:

• Falls. A simple fall can fracture one or both lower leg bones. A much higher impact is usually needed to break the thighbone.
• Motor vehicle accidents. All three leg bones can break during a motor vehicle accident. Fractures can occur when your knees become jammed against the dashboard during a collision or with damage to the car hitting your legs.
• Sports injuries. Extending your leg beyond its natural limits during contact sports can cause a broken leg. So can a fall or a direct blow — such as from a hockey stick or an opponent's body.
• Child abuse. In children, a broken leg may be the result of child abuse, especially when such an injury occurs before the child can walk.
• Overuse. Stress fractures are tiny cracks that develop in the weight-bearing bones of the body, including the shinbone. Stress fractures are usually caused by repetitive force or overuse, such as running long distances. But they can occur with regular use of a bone that's been weakened by a condition such as osteoporosis.

Stress fractures are often the result of repetitive stress to the leg bones from physical activities, such as:

• Running
• Ballet dancing
• Basketball
• Marching

Contact sports, such as hockey and football, also may pose a risk of direct blows to the leg, which can result in a fracture.

Stress fractures outside of sport situations are more common in people who have:

• Decreased bone density (osteoporosis)
• Diabetes
• Rheumatoid arthritis

Complications of a broken leg may include:

• Knee or ankle pain. A broken bone in your leg may produce pain in your knee or ankle.
• Bone infection (osteomyelitis). If a broken bone cuts through the skin and causes a wound, it is called an open fracture. If you have an open fracture, the bone may be exposed to germs that can cause infection.
• Poor or delayed healing. A severe leg fracture may not heal quickly or completely. This is particularly common in an open fracture of the tibia because of lower blood flow to this bone.
• Nerve or blood vessel damage. Leg fractures can injure nearby nerves and blood vessels. Seek immediate medical help if you notice any numbness, pale skin or circulation problems.
• Compartment syndrome. This condition causes pain, swelling and sometimes disability in muscles near the broken bone. This is a rare complication that is more common with high-impact injuries, such as a car or motorcycle accident.
• Arthritis. Fractures that extend into the joint and poor bone alignment can cause osteoarthritis years later. If your leg starts to hurt long after a break, see your health care provider for an evaluation.
• Unequal leg length. The long bones of a child grow from the ends of the bones, in softer areas called growth plates. If a fracture goes through a growth plate, that limb might eventually become shorter or longer than the opposite limb.

A broken leg can't always be prevented. But these basic tips may reduce your risk:

• Build bone strength. Calcium-rich foods, such as milk, yogurt and cheese, can help build strong bones. A calcium or vitamin D supplement also may improve bone strength. Ask your health care provider if these supplements are right for you.
• Wear proper athletic shoes. Choose the appropriate shoe for your favorite sports or activities. And replace athletic shoes regularly. Discard sneakers as soon as the tread or heel wears out or if the shoes are wearing unevenly.
• Cross-train. Alternating activities can prevent stress fractures. Rotate running with swimming or biking. If you run on a sloped track indoors, alternate the direction of your running to even out the stress on your skeleton.

During the physical exam, the health care provider will inspect the affected area for tenderness, swelling, deformity or an open wound.

X-rays can usually pinpoint the location of the break and determine the extent of injury to any adjacent joints. Occasionally, computerized tomography (CT) or magnetic resonance imaging (MRI) is needed for more detailed images. For instance, you may need a CT scan or an MRI for a suspected stress fracture, since X-rays often fail to reveal this injury.

Treatment of a broken leg will vary, depending on the type and location of the break. Stress fractures may require only rest and immobilization, while other breaks may need surgery for best healing. Fractures are classified into one or more of the following categories:

• Open fracture. In this type of fracture, the skin is pierced by the broken bone. This is a serious condition that requires immediate treatment to decrease the chance of an infection.
• Closed fracture. In closed fractures, the surrounding skin remains intact.
• Incomplete fracture. This term means that the bone is cracked but not separated into two parts.
• Complete fracture. In complete fractures, the bone has broken into two or more parts.
• Displaced fracture. In this type of fracture, the bone fragments on each side of the break are not aligned. A displaced fracture may require surgery to realign the bones properly.
• Greenstick fracture. In this type of fracture, the bone cracks but doesn't break all the way through — like when you try to break a green stick of wood. Greenstick fractures are more likely to occur in children because a child's bones are softer and more flexible than those of an adult.

Setting the leg

Treatment for a broken leg usually begins in an emergency room or urgent care clinic. Here, health care providers typically evaluate the injury and immobilize the leg with a splint. If you have a displaced fracture, the care team may need to move the pieces of bone back into their proper positions before applying a splint — a process called reduction. Some fractures are splinted at first to allow swelling to subside. A cast is then used once there is less swelling.

Immobilization

For a broken bone to heal properly, its movement needs to be restricted. A splint or a cast is often used to immobilize the broken bone. You may need to use crutches or a cane to keep weight off the affected leg for at least 6 weeks.

Medications

A pain reliever such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others), or a combination of the two, can reduce pain and inflammation. If you're experiencing severe pain, your health care provider might prescribe stronger pain medications.

Therapies

After your cast or splint is removed, you'll likely need rehabilitation exercises or physical therapy to reduce stiffness and restore movement in the injured leg. Because you haven't moved your leg for a while, you may even have stiffness and weakened muscles in uninjured areas. Rehabilitation can help, but it may take up to several months — or even longer — for complete healing of severe injuries.

Surgery and other procedures

Immobilization with a cast or splint heals most broken bones. However, you may need surgery to implant plates, rods or screws to maintain proper position of the bones during healing. This type of surgery is more likely in people who have:

• Multiple fractures
• An unstable or displaced fracture
• Loose bone fragments that could enter a joint
• Damage to the surrounding ligaments
• Fractures that extend into a joint
• A fracture that is the result of a crushing accident

Some injuries are treated with a metal frame outside the leg attached to the bone with pins. This device provides stability during the healing process and is usually removed after about 6 to 8 weeks. There's a risk of infection around the surgical pins.

Depending on the severity of the break, your health care provider may recommend examination by an orthopedic surgeon.

What you can do

You may want to write a list that includes:

• Detailed descriptions of the symptoms and what caused the injury
• Information about past medical problems
• All the medications and dietary supplements you or your child takes
• Questions you want to ask the health care provider

For a broken leg, some basic questions to ask your care provider include:

• What kinds of tests are needed?
• What is the best course of action?
• Is surgery necessary?
• What are the alternatives to the primary treatment you're suggesting?
• What restrictions need to be followed?
• Should I see a specialist?
• What pain medications do you recommend?

Don't hesitate to ask any other questions you have.

What to expect from your doctor

Your health care provider is likely to ask you questions, including:

• How and when did your injury occur?
• Were there any other injuries or areas of pain?
• Have you had broken bones in the past or a history of osteoporosis?
• Do you have any numbness, tingling or loss of sensation to the injured area?
• Were you able to get up and stand or walk, bearing weight on your leg, after your injury?
• How severe is the pain from your injury?
• What, if anything, seems to improve the pain?
• What, if anything, appears to worsen the pain?

For injuries to children, the evaluation often includes routine questions to rule out concerns for intentional injury or child abuse.