Your child has been diagnosed with a leg-length discrepancy. This means that your child?s legs are slightly different lengths, with one leg longer than the other. The difference in lengths can vary widely. The larger the difference in lengths, the more problems that can result as the child gets older. Because of this, your child may be referred to a pediatric orthopedist (doctor specializing in treating bone and joint problems in children) for evaluation and possible treatment.
Sometimes the cause of LLD is unknown, yet the pattern or combination of conditions is consistent with a certain abnormality. Examples include underdevelopment of the inner or outer side of the leg (hemimelias) or (partial) inhibition of growth of one side of the body of unknown cause (hemihypertrophy). These conditions are present at birth, but the limb length difference may be too small to be detected. As the child grows, the LLD increases and becomes more noticeable. In hemimelia, one of the two bones between the knee and the ankle (tibia or fibula) is abnormally short. There also may be associated foot or knee abnormalities. Hemihypertrophy or hemiatrophy are rare conditions in which there is a difference in length of both the arm and leg on only one side of the body. There may also be a difference between the two sides of the face. Sometimes no cause can be found. This type of limb length is called idiopathic. While there is a cause, it cannot be determined using currect diagnostic methods.
Faulty feet and ankle structure profoundly affect leg length and pelvic positioning. The most common asymmetrical foot position is the pronated foot. Sensory receptors embedded on the bottom of the foot alert the brain to the slightest weight shift. Since the brain is always trying to maintain pelvic balance, when presented with a long left leg, it attempts to adapt to the altered weight shift by dropping the left medial arch (shortening the long leg) and supinating the right arch to lengthen the short leg.1 Left unchecked, excessive foot pronation will internally rotate the left lower extremity, causing excessive strain to the lateral meniscus and medial collateral knee ligaments. Conversely, excessive supination tends to externally rotate the leg and thigh, creating opposite knee, hip and pelvic distortions.
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 object of treatment for leg length discrepancy is to level the pelvis and equalize the length of the two limbs. Inequalities of 2-2.5 centimeters can be handled with the following. Heel lifts/ adjustable heel lifts can be used inside a shoe where shoes have a full heel counter. Heel lifts may be added to the heel on the outside of the shoe along with an internal heel lift. Full platforms along the forefoot and rearfoot area of a shoe can be added. There are many different adjustable heel lifts available on the market. For treatment of a leg length discrepancy, consult your physician. They may refer you to a Physiotherapist or Chiropractor for determination of the type of LLD. A Certified Pedorthist (Canada) will treat a structural leg length discrepancy with a heel lift or in larger discrepancies a footwear modification.
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.