What is Limb Length Discrepancy (LLD)?

A limb length discrepancy (LLD) is when one arm or leg is longer than the other arm or leg. A difference in leg lengths is more likely to be noticed and to affect activities of daily living. There are many different reasons to have a leg length discrepancy, but there are two main causes: 1) your child was born with a condition that caused one leg to grow slower than the other or 2) something happened during your child’s lifetime that affected the length of the bone (i.e. a fracture) or affected the growth center of the bone (trauma, infection, etc.). Often as babies grow and start standing or walking, their parents will notice a difference. Your doctor should be able to help you determine the cause of your leg length discrepancy.

Leg length discrepancies are very common. In fact, many of us have a small difference in our leg lengths. However, most people don’t notice the difference or require any treatment. When the difference measures more than 1.5 to 2.0 cm (5/8 of an inch), most physicians recommend having the discrepancy evaluated. In order to assess the limb length discrepancy, your child will have a thorough physical exam. Often, the team will obtain standing x-ray films in order to get a more exact measurement of the limb discrepancy.

If your child’s limb length discrepancy is great enough and affects their daily living, they may need treatment. There are both non-surgical and surgical treatment options. One non-surgical option is a shoe lift. A simple shoe lift can either be added to the bottom of the shoe or inserted into the shoe and can help to correct some leg length differences. Of course, this treatment method does not correct the discrepancy whenever the lift is not being worn. While shoe lifts can be a helpful non-surgical option, some children have differences in leg lengths that are too great and may benefit from surgical treatment. Each of these techniques produces a permanent correction of the leg length. Depending on your child’s condition, you and your doctor may choose to shorten the long leg or lengthen the short leg.

X-ray of lower extremities showing a leg length discrepancy