True Leg Length Discrepancy Test

Overview

Some people have an ?apparent? LLD which may make the affected leg seem longer than the other leg. There are several factors that can contribute to this feeling. Most commonly, contractures or shortening of the muscles surrounding the hip joint and pelvis make the involved leg feel longer, even when both legs are really the same length. Additionally, contractures of the muscles around the lower back from spinal disorders (i.e. arthritis, spinal stenosis), curvatures of the spine from scoliosis, and deformities of the knee or ankle joint can make one leg seem longer or shorter. In the general public, some people have an ?apparent LLD? as long as one half inch but usually don?t notice it because the LLD occurs over time. A ?true? LLD is where one leg is actually longer than the other. Patients can have unequal leg lengths of 1/4? to 1/2? and never feel it too! You can also have combinations of ?True? and ?Apparent? LLDs. During total hip replacement surgery, the surgeon may ?lengthen? the involved leg by stretching the muscles and ligaments that were contracted, as well as by restoring the joint space that had become narrowed from the arthritis. This is usually a necessary part of the surgery because it also provides stability to the new hip joint. Your surgeon takes measurements of your leg lengths on x-ray prior to surgery. Your surgeon always aims for equal leg lengths if at all possible and measures the length of your legs before and during surgery in order to achieve this goal. Occasionally, surgeons may need to lengthen the operable leg to help improve stability and prevent dislocations as well improve the muscle function around the hip.Leg Length Discrepancy

Causes

Leg discrepancy can develop from a medical issue in any portion of the femur or tibia. One leg may lengthen, but leg shortening is much more common. Factors that can cause leg length discrepancy include inherited growth deficiencies. Infections. A bone infection can cause delayed growth in the affected limb. Injury. If your child breaks a leg, it may be shorter once it heals. This is most likely to happen if the fracture or break was complicated, an open fracture, or an injury that affected the growth plate near the end of the bone. Alternatively, a break can cause bones to grow faster after healing, making a leg longer. Tumors. Legg-Calve-Perthes disease. This is a condition that affects the ball (femoral head) of the hip joint. The femoral head may be friable and damage easily, sometimes leading to shortening of the thigh bone. Hemihypertrophy. In children with this condition, one side of the body grows more quickly than the other. Vascular malformations. These are abnormal clusters of veins and arteries that can form close to the bone and stimulate growth. Juvenile arthritis. Inflammation from arthritis can stimulate growth in the affected leg and cause discrepancy.

Symptoms

The symptoms of limb deformity can range from a mild difference in the appearance of a leg or arm to major loss of function of the use of an extremity. For instance, you may notice that your child has a significant limp. If there is deformity in the extremity, the patient may develop arthritis as he or she gets older, especially if the lower extremities are involved. Patients often present due to the appearance of the extremity (it looks different from the other side).

Diagnosis

Leg length discrepancy may be diagnosed during infancy or later in childhood, depending on the cause. Conditions such as hemihypertrophy or hemiatrophy are often diagnosed following standard newborn or infant examinations by a pediatrician, or anatomical asymmetries may be noticed by a child's parents. For young children with hemihypertophy as the cause of their LLD, it is important that they receive an abdominal ultrasound of the kidneys to insure that Wilm's tumor, which can lead to hypertrophy in the leg on the same side, is not present. In older children, LLD is frequently first suspected due to the emergence of a progressive limp, warranting a referral to a pediatric orthopaedic surgeon. The standard workup for LLD is a thorough physical examination, including a series of measurements of the different portions of the lower extremities with the child in various positions, such as sitting and standing. The orthopaedic surgeon will observe the child while walking and performing other simple movements or tasks, such as stepping onto a block. In addition, a number of x-rays of the legs will be taken, so as to make a definitive diagnosis and to assist with identification of the possible etiology (cause) of LLD. Orthopaedic surgeons will compare x-rays of the two legs to the child's age, so as to assess his/her skeletal age and to obtain a baseline for the possibility of excessive growth rate as a cause. A growth chart, which compares leg length to skeletal age, is a simple but essential tool used over time to track the progress of the condition, both before and after treatment. Occasionally, a CT scan or MRI is required to further investigate suspected causes or to get more sophisticated radiological pictures of bone or soft tissue.

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.

Leg Length Discrepancy Insoles

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Surgical Treatment

In growing children, legs can be made equal or nearly equal in length with a relatively simple surgical procedure. This procedure slows down the growth of the longer leg at one or two growth sites. Your physician can tell you how much equalization can be gained by this procedure. The procedure is performed under X-ray control through very small incisions in the knee area. This procedure will not cause an immediate correction in length. Instead, the limb length discrepancy will gradually decrease as the opposite extremity continues to grow and "catch up." Timing of the procedure is critical. The goal is to reach equal leg length by the time growth normally ends. This is usually in the mid-to-late teenage years. Disadvantages of this option include the possibility of slight over-correction or under-correction of the limb length discrepancy. In addition, the patient's adult height will be less than if the shorter leg had been lengthened. Correction of significant limb length discrepancy by this method may make a patient's body look slightly disproportionate because of the shorter leg. In some cases the longer leg can be shortened, but a major shortening may weaken the muscles of the leg. In the thighbone (femur), a maximum of 3 inches can be shortened. In the shinbone, a maximum of 2 inches can be shortened.