There are generally two kinds of leg length discrepancies. Structural discrepancy occurs when either the thigh (femur) or shin (tibia) bone in one leg is actually shorter than the corresponding bone in the other leg. Functional discrepancy occurs when the leg lengths are equal, but symmetry is altered somewhere above the leg, which in turn disrupts the symmetry of the legs. For example, developmental dislocation of the hip (DDH) can cause a functional discrepancy. In DDH, the top of the leg bone (femur) that is not properly positioned in the hip socket may hang lower than the femur on the other side, giving the appearance and symptoms of a leg length discrepancy.
Leg length discrepancies can be caused by poor alignment of the pelvis or simply because one leg is structurally longer than the other. Regardless of the reason, your body wants to be symmetrical and will do its best to compensate for the length difference. The greater the leg length difference, the earlier the symptoms will present themselves to the patient. Specific diagnoses that coincide with leg length discrepancy include: scoliosis, lumbar herniated discs, sacroiliitis, pelvic obiliquity, greater trochanteric bursitis, hip arthritis, piriformis syndrome, patellofemoral syndrome and foot pronation. Other potential causes could be due to an injury (such as a fracture), bone disease, bone tumors, congenital problems (present at birth) or from a neuromuscular problem.
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.
The doctor carefully examines the child. He or she checks to be sure the legs are actually different lengths. This is because problems with the hip (such as a loose joint) or back (scoliosis) can make the child appear to have one shorter leg, even though the legs are the same length. An X-ray of the child?s legs is taken. During the X-ray, a long ruler is put in the image so an accurate measurement of each leg bone can be taken. If an underlying cause of the discrepancy is suspected, tests are done to rule it out.
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.
Surgeries for LLD are designed to do one of three general things ? shorten the long leg, stop or slow the growth of the longer or more rapidly growing leg, or lengthen the short leg. Stopping the growth of the longer leg is the most commonly utilized of the three approaches and involves an operation known as an epiphysiodesis , in which the growth plate of either the lower femur or upper tibia is visualized in the operating room using fluoroscopy (a type of real-time radiographic imaging) and ablated , which involves drilling into the region several times, such that the tissue is no longer capable of bone growth. Because the epiphyseal growth capabilities cannot be restored following the surgery, proper timing is crucial. Usually the operation is planned for the last 2 to 3 years of growth and has excellent results, with children leaving the hospital within a few days with good mobility. However, it is only appropriate for LLD of under 5cm.