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.
Common causes include bone infection, bone diseases, previous injuries, or broken bones. Other causes may include birth defects, arthritis where there is a loss of articular surface, or neurological conditions.
In addition to the distinctive walk of a person with leg length discrepancy, over time, other deformities may be noted, which help compensate for the condition. Toe walking on the short side to decrease the swaying during gait. The foot will supinate (high arch) on the shorter side. The foot will pronate (flattening of the arch) on the longer side. Excessive pronation leads to hypermobility and instability, resulting in metatarsus primus varus and associated unilateral juvenile hallux valgus (bunion) deformity.
Infants, children or adolescents suspected of having a limb-length condition should receive an evaluation at the first sign of difficulty in using their arms or legs. In many cases, signs are subtle and only noticeable in certain situations, such as when buying clothing or playing sports. Proper initial assessments by qualified pediatric orthopedic providers can reduce the likelihood of long-term complications and increase the likelihood that less invasive management will be effective. In most cases, very mild limb length discrepancies require no formal treatment at all.
Non Surgical Treatment
In order to measure for correction, use a series of blocks or sheets of firm material (cork or neoprene) of varying thickness, e.g., 1/8", 1/4", and 1/2". Place them under the short limb, either under the heel or the entire foot, depending on the pathology, until the patient feels most balanced. Usually you will not be able to correct for the full amount of the imbalance at the outset. The longer a patient has had the LLD, the less likely he or she will be able to tolerate a full correction immediately. This is a process of incremental improvements. 2 inch External Platform Lift Bear in mind that the initial lift may need to be augmented as the patient's musculoskeletal system begins to adjust. It is often recommended that the initial buildup should be 50 percent of the total. After a suitable break-in period, one month say, another 25 percent can be added. If warranted, the final 25 percent can be added a month later. Once you determine how much lift the patient can handle, you then need to decide how to best apply it. There are certain advantages and disadvantages to using either internal or external heel lifts.
Epiphysiodesis is a surgical option designed to slow down the growth of the long leg over a period of months to years. It is only used in growing children. The operation involves a general anaesthetic. Small incisions are made around the knee near the growth plates of the thigh bone and the shin bone. The growth plates are prevented from growing by the use of small screws and plates (?8 - plates?). The screws are buried beneath the skin and are not visible. Stitches are buried beneath the skin and do not need to be removed. The child is normally in hospital for 2-3 days. The child can weight bear immediately and return back to normal activity within a few weeks. Long term follow up is required to monitor the effects of the surgery. The timing of the surgery is based on the amount of growth predicted for the child. Therefore, this procedure can under- and over-correct the difference in leg length. Occasionally the screws have to be removed to allow growth to continue. This procedure can be used on one half of the growth plate to correct deformity in a limb e.g. knock-knees or bow legs. This is known as hemiepiphysiodesis.