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 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.
Many people walk around with LLD?s of up to 2 cm. and not even know it. However, discrepancies above 2 cm. becomes more noticeable, and a slight limp is present. But even up to 3 cm. a small lift compensates very well, and many patients are quite happy with this arrangement. Beyond 3 cm. however, the limp is quite pronounced, and medical care is often sought at that point. Walking with a short leg gait is not only unsightly, but increases energy expenditure during ambulation. It could also put more stress on the long leg, and causes functional scoliosis. Where the discrepancy is more severe, walking becomes grotesque or virtually impossible.
A qualified musculoskeletal expert will first take a medical history and conduct a physical exam. Other tests may include X-rays, MRI, or CT scan to diagnose the root cause.
Non Surgical Treatment
You and your physician should discuss whether treatment is necessary. For minor LLDs in adults 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 one inch. For these small differences, your physician may recommend a shoe lift. A lift fitted to the shoe can often improve your walking and running, as well as relieve back pain caused by LLD. Shoe lifts are inexpensive and can be removed if they are not effective. They do, however, add weight and stiffness to the shoe.
shoe lifts for height
Shortening techniques can be used after skeletal maturity to achieve leg length equality. Shortening can be done in the proximal femur using a blade plate or hip screw, in the mid-diaphysis of the femur using a closed intramedullary (IM) technique, or in the tibia. Shortening is an accurate technique and involves a much shorter convalescence than lengthening techniques. Quadriceps weakness may occur with femoral shortenings, especially if a mid-diaphyseal shortening of greater than 10% is done. If the femoral shortening is done proximally, no significant weakness should result. Tibial shortening can be done, but there may be a residual bulkiness to the leg, and risks of nonunion and compartment syndrome are higher. If a tibial shortening is done, shortening over an IM nail and prophylactic compartment release are recommended. We limit the use of shortenings to 4 to 5 cm leg length inequality in patients who are skeletally mature.