Functional Leg Length Discrepancy Symptoms

Overview

Differences between lengths of the two upper extremities (upper and/or lower arms) or between the lengths of the two lower extremities (upper and/or lower legs) are called limb length discrepancy (LLD). A limb length discrepancy may be due to a normal variation that we all have between the two sides of our bodies, or it may be due to other causes. Some differences are so common that they are normal and need no treatment. For example, one study reported that 32 percent of 600 military recruits had a 5mm to 15mm (approximately 1/5 to 3/5 inch) difference between the lengths of their two lower extremities; this is a normal variation. Greater differences may need treatment because a discrepancy can affect a patient?s well being and quality of life.Leg Length Discrepancy

Causes

Leg length discrepancies can be caused by: hip and knee replacements, lower limb injuries, bone diseases, neuromuscular issues and congenital problems. Although discrepancies of 2 cm or less are most common, discrepancies can be greater than 6 cm. People who have LLD tend to make up for the difference by over bending their longer leg or standing on the toes of their shorter leg. This compensation leads to an inefficient, up and down gait, which is quite tiring and over time can result in posture problems as well as pain in the back, hips, knees and ankles.

Symptoms

Patients with significant lower limb length discrepancies may walk with a limp, have the appearance of a curved spine (non-structural scoliosis), and experience back pain or fatigue. In addition, clothes may not fit right.

Diagnosis

There are several orthopedic tests that are used, but they are rudimentary and have some degree of error. Even using a tape measure with specific anatomic landmarks has its errors. Most leg length differences can be seen with a well trained eye, but I always recommend what is called a scanagram, or a x-ray bone length study (see picture above). This test will give a precise measurement in millimeters of the length difference.

Non Surgical Treatment

In some circumstances, the physician will recommend a non-surgical form of treatment. Non-surgical treatments include orthotics and prosthetics. Orthotics are a special type of lift placed in or on a shoe that can be used in the treatment of leg length discrepancies between two and six centimeters. In pediatric patients who have large discrepancies and are not good candidates for other treatment forms, prosthetics can be helpful.

Leg Length Discrepancy Insoles

Surgical Treatment

Surgeries to lengthen a leg are generally only performed when there is a difference in leg length of greater than four centimeters. These types of surgeries can be more difficult and have more complications, such as infections, delayed healing, dislocations, and high blood pressure. In a several step process, bone lengthening surgeries involve cutting a bone in two in order to allow new bone growth to occur. After the bone is cut, a special apparatus is worn with pins that will pull the bone apart at approximately one millimeter per day. This causes osteogenesis, or new bone growth, in between the cut bone segments. A cast or brace may be required for several months after surgery to allow the new bone growth to harden and provide extra support.

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