A Leg Length Inequality or Leg Length Discrepancy is exactly as it sounds. One or more bones (the Femur or thigh bone, the Tibia or shin bone, and/or the joint spacing within the knee) are unequal in total length when measured in comparison to the same structures on the opposite side. It is common for people to have one leg longer than the other. In fact, it is more typical to be asymmetrical than it is to be symmetrical.
The causes of LLD are many, including a previous injury, bone infection, bone diseases (dysplasias), inflammation (arthritis) and neurologic conditions. Previously broken bones may cause LLD by healing in a shortened position, especially if the bone was broken in many pieces (comminuted) or if skin and muscle tissue around the bone were severely injured and exposed (open fracture). Broken bones in children sometimes grow faster for several years after healing, causing the injured bone to become longer. Also, a break in a child?s bone through a growth center (located near the ends of the bone) may cause slower growth, resulting in a shorter extremity. Bone infections that occur in children while they are growing may cause a significant LLD, especially during infancy. Bone diseases may cause LLD, as well; examples are neurofibromatosis, multiple hereditary exostoses and Ollier disease. Inflammation of joints during growth may cause unequal extremity length. One example is juvenile rheumatoid arthritis. Osteoarthritis, the joint degeneration that occurs in adults, very rarely causes a significant LLD.
The most common symptom of all forms of LLD is chronic backache. In structural LLD the sufferer may also experience arthritis within the knee and hip are, flank pain, plantar fasciitis and metatarsalgia all on the side that is longer. Functional LLD sufferers will see similar conditions on the shorter side.
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.
Non Surgical Treatment
The treatment of LLD depends primarily on the diagnosed cause, the age of the patient, and the severity of the discrepancy. Non-operative treatment is usually the first step in management and, in many cases, LLD is mild or is predicted to lessen in the future, based on growth rate estimates in the two legs. In such cases, no treatment may be necessary or can be delayed until a later stage of physical maturity that allows for clearer prognostic approximation. For LLD of 2cm to 2.5cm, treatment may be as simple as insertion of a heel lift or other shoe insert that evens out leg lengths, so to speak. For more severe cases, heel lifts can affect patient comfort when walking, decrease ankle stability, and greatly increase the risk of sprains. For infants with congenital shortening of the limb, a prosthetic ? often a custom-fit splint made of polypropylene ? may be successful in treating more severe LLD without surgery. In many instances, however, a surgical operation is the best treatment for LLD.
Surgery to shorten the longer leg. This is less involved than lengthening the shorter leg. Shortening may be done in one of two ways. Closing the growth plate of the long leg 2-3 years before growth ends (around age 11-13), letting the short leg catch up. This procedure is called an epiphysiodesis. Taking some bone from the longer leg once growth is complete to even out leg lengths. Surgery to lengthen the shorter leg. This surgery is more involved than surgery to shorten a leg. During this surgery, cuts are made in the leg bone. An external metal frame and bar are attached to the leg bone. This frame and bar slowly pull on the leg bone, lengthening it. The frame and bar must be worn constantly for months to years. When the frame and bar are removed, a leg cast is required for several months. This surgery requires careful and continued follow-up with the surgeon to be sure that healing is going well.