Patient Education

What is limb Length Discrepancy?

Differences between the lengths of the upper and/or lower arms and the upper and/or lower legs are called limb length discrepancies (LLD). Except in extreme cases, arm length differences cause little or no problem in how the arms function. A limb length difference may simply be a mild variation between the two sides of the body. This is not unusual in the general population.

What are Cause of limb Length Discrepancy?

Previous Injury to a Bone

A broken leg bone may lead to a limb length discrepancy if it heals in a shortened position. This is more likely if the bone was broken in many pieces. It also is more likely if skin and muscle tissue around the bone were severely injured and exposed, as in an open fracture.

Infections of bones

Bone infections that occur in children while they are growing may cause a significant limb length discrepancy. This is especially true if the infection happens in infancy. Inflammation of joints during growth may cause unequal leg length. One example is juvenile arthritis.

Dysplasias

Bone diseases may cause limb length discrepancy, as well. Examples are:

• Neurofibromatosis

• Multiple hereditary exostoses

• Ollier disease

Other Causes

Other causes include inflammation (arthritis) and neurologic conditions

Sometimes the cause of limb length discrepancy is unknown, particularly in cases involving underdevelopment of the inner or outer side of the leg, or partial overgrowth of one side of the body.

How to Diagnosis limb Length Discrepancy?

Limb length discrepancy can be measured by a physician during a physical examination and through X-rays. Usually, the physician measures the level of the hips when the child is standing barefoot. A series of measured wooden blocks may be placed under the short leg until the hips are level. If the physician believes a more precise measurement is needed, he or she may use X-rays. In growing children, a physician may repeat the physical examination and X-rays every six months to a year to see if the limb length discrepancy has increased or remained unchanged. A limb length discrepancy may be detected on a screening examination for curvature of the spine (scoliosis). But limb length discrepancy does not cause scoliosis.

What are Symptoms?

The effects of limb length discrepancy vary from patient to patient, depending on the cause and size of the difference. Differences of 3 1/2 percent to 4 percent of the total length of the leg (about 4 cm or 1 2/3 inches in an average adult) may cause noticeable abnormalities when walking. These differences may require the patient to exert more effort to walk.

What are Treatment options?

For minor limb length discrepancy in patients with no deformity, treatment may not be necessary. Because the risks may outweigh the benefits, surgical treatment to equalize leg lengths is usually not recommended if the difference is less than 1 inch.

Surgical Treatment

In growing children, legs can be made equal or nearly equal in length with a relatively simple surgical procedure. This procedure slows down the growth of the longer leg at one or two growth sites. The procedure is performed under X-ray control through very small incisions in the knee area. This procedure will not cause an immediate correction in length. Instead, the limb length discrepancy will gradually decrease as the opposite extremity continues to grow and "catch up."In some cases, the longer leg can be shortened, but a major shortening may weaken the muscles of the leg. In the thighbone (femur), a maximum of 3 inches can be shortened. In the shinbone, a maximum of 2 inches can be shortened. Surgical lengthening of the shorter leg is another choice.