What Is Leg Length Discrepancy?

Kids with a leg length discrepancy have legs that are different lengths. This happens because the thigh bone (femur), shinbones (tibia or fibula), or both are shorter in one leg.

What Are the Signs & Symptoms of Leg Length Discrepancy?

Signs and symptoms of a leg length discrepancy depend on the cause and how much shorter one leg is. A small difference in leg length might not be noticeable at all. A bigger difference can cause a limp or pain. It can also lead to arthritis as an adult.

Depending on how old a child is and the cause of the discrepancy, the difference may stay the same or get worse as the child grows.

What Causes Leg Length Discrepancy?

Leg length discrepancy can be present at birth (called congenital) but might not be noticeable until a child gets older. It also can develop when a child is older (called acquired).

Causes of congenital leg length discrepancy include:

• fibular hemimelia (when a baby is born with a short or missing shinbone)
• focal femoral deficiency (when a baby is born with a short or missing thighbone)
• hemihypertrophy (when one side of the body grows larger than the other)

Causes of acquired leg length discrepancy include:

• a broken leg bone
• a bone infection

An idiopathic leg length discrepancy is one where the cause isn't known.

How Is Leg Length Discrepancy Diagnosed?

To diagnose a limb length discrepancy, orthopedic  specialists (doctors and other health care providers who treat bone and muscle problems):

• talk to the family and the child (if they're old enough to understand)
• do a physical exam
• measure both legs
• watch how the child walks
• take X-rays

How Is Leg Length Discrepancy Treated?

Treating a slight difference in leg length can mean lengthening the shorter leg or shortening the longer leg. A shoe lift can even out small differences, and might be all that some kids need. But if the difference in leg length is more than 1 inch (2.5 cm) or gets worse as the child grows, surgery can help. Kids may need more than one surgery as they grow.

An option for kids who are still growing is epiphysiodesis (pronounced: ep-i-fiz-ee-uh-DEE-sis). In this relatively simple outpatient surgery, one or two of the growth plates (areas at the end of bones where new growth happens) in the longer leg are scraped or compressed with surgical plates and screws. The surgery slows or stops the longer leg from growing so the shorter leg can catch up.

If a child has stopped growing, orthopedists can sometimes correct a leg length discrepancy by shortening the longer leg. This is done by removing a piece of bone from the longer leg.

Limb lengthening surgery also can be done. In this surgery, the shorter limb is lengthened through a device on the outside of the body (an external fixator) or a device placed inside the bone (limb lengthening device). This surgery requires a stay in the hospital and weeks to months of follow-up care and rehabilitation.

How Can Parents Help?

Fixing leg length discrepancy can take many years. Parents and the orthopedic care team play a big role in treatment.

Here are things you can do:

• Talk to your child's care team about treatment and healing. Ask questions. Find out what each surgery is for and how to care for your child afterward.
• Take your child to all scheduled medical visits.
• If your child is old enough, talk about treatments and what to expect. Include older kids in surgery decisions when you can.

What Else Should I Know?

Your orthopedic team will help you find the best treatment for your child. Take time to understand exactly what will happen at each stage of the treatment plan. This way, you and your child know what to expect and can follow the plan. The orthopedic care team is there to answer any questions and help you get the best result for your child.