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Correcting Leg Length Discrepancy After Hip Replacement

July 1, 2017
Overview

Leg shortening is employed when LLD is severe and when a patient has already reached skeletal maturity. The actual surgery is called an osteotomy , which entails the removal of a small section of bone in the tibia (shinbone) and sometimes the fibula as well, resulting in the loss of around an inch in total height. Leg lengthening is a difficult third option that has traditionally had a high complication rate. Recently, results have improved somewhat with the emergence of a technique known as callotasis , in which only the outer portion of the bone (the cortex ) is cut, (i.e. a corticotomy ). This allows the bone to be more easily lengthened by an external fixation device that is attached to either side of the cut bone with pins through the skin. The ?ex-fix,' as it is sometimes called, is gradually adjusted by an orthopaedic surgeon, and healing can occur at the same time that the leg is being distracted , or lengthened over time. Unlike epiphysiodesis, leg lengthening procedures can be performed at almost any skeletal or chronological age.Leg Length Discrepancy

Causes

Limb-length conditions can result from congenital disorders of the bones, muscles or joints, disuse or overuse of the bones, muscles or joints caused by illness or disease, diseases, such as bone cancer, Issues of the spine, shoulder or hip, traumatic injuries, such as severe fractures that damage growth plates.

Symptoms

As patients develop LLD, they will naturally and even unknowingly attempt to compensate for the difference between their two legs by either bending the longer leg excessively or standing on the toes of the short leg. When walking, they are forced to step down on one side and thrust upwards on the other side, which leads to a gait pattern with an abnormal up and down motion. For many patients, especially adolescents, the appearance of their gait may be more personally troublesome than any symptoms that arise or any true functional deficiency. Over time, standing on one's toes can create a contracture at the ankle, in which the calf muscle becomes abnormally contracted, a condition that can help an LLD patient with walking, but may later require surgical repair. If substantial enough, LLD left untreated can contribute to other serious orthopaedic problems, such as degenerative arthritis, scoliosis, or lower back pain. However, with proper treatment, children with leg length discrepancy generally do quite well, without lingering functional or cosmetic deficiencies.

Diagnosis

The most accurate method to identify leg (limb) length inequality (discrepancy) is through radiography. It?s also the best way to differentiate an anatomical from a functional limb length inequality. Radiography, A single exposure of the standing subject, imaging the entire lower extremity. Limitations are an inherent inaccuracy in patients with hip or knee flexion contracture and the technique is subject to a magnification error. Computed Tomography (CT-scan), It has no greater accuracy compared to the standard radiography. The increased cost for CT-scan may not be justified, unless a contracture of the knee or hip has been identified or radiation exposure must be minimized. However, radiography has to be performed by a specialist, takes more time and is costly. It should only be used when accuracy is critical. Therefore two general clinical methods were developed for assessing LLI. Direct methods involve measuring limb length with a tape measure between 2 defined points, in stand. Two common points are the anterior iliac spine and the medial malleolus or the anterior inferior iliac spine and lateral malleolus. Be careful, however, because there is a great deal of criticism and debate surrounds the accuracy of tape measure methods. If you choose for this method, keep following topics and possible errors in mind. Always use the mean of at least 2 or 3 measures. If possible, compare measures between 2 or more clinicians. Iliac asymmetries may mask or accentuate a limb length inequality. Unilateral deviations in the long axis of the lower limb (eg. Genu varum,?) may mask or accentuate a limb length inequality. Asymmetrical position of the umbilicus. Joint contractures. Indirect methods. Palpation of bony landmarks, most commonly the iliac crests or anterior iliac spines, in stand. These methods consist in detecting if bony landmarks are at (horizontal) level or if limb length inequality is present. Palpation and visual estimation of the iliac crest (or SIAS) in combination with the use of blocks or book pages of known thickness under the shorter limb to adjust the level of the iliac crests (or SIAS) appears to be the best (most accurate and precise) clinical method to asses limb inequality. You should keep in mind that asymmetric pelvic rotations in planes other than the frontal plane may be associated with limb length inequality. A review of the literature suggest, therefore, that the greater trochanter major and as many pelvic landmarks should be palpated and compared (left trochanter with right trochanter) when the block correction method is used.

Non Surgical Treatment

Treatments for limb-length discrepancies and differences vary, depending on the cause and severity of the condition. At Gillette, our orthopedic surgeons are experts in typical and atypical growth and development. Our expertise lets us plan treatments that offer a lifetime of benefits. Treatments might include monitoring growth and development, providing noninvasive treatments or therapy, and providing a combination of orthopedic surgical procedures. To date, alternative treatments (such as chiropractic care or physical therapy) have not measurably altered the progression of or improved limb-length conditions. However, children often have physical or occupational therapy to address related conditions, such as muscle weakness or inflexibility, or to speed recovery following a surgical procedure. In cases where surgical treatment isn?t necessary, our orthopedists may monitor patients and plan noninvasive treatments, such as, occupational therapy, orthoses (braces) and shoe inserts, physical therapy, prostheses (artificial limbs).

Leg Length

leg length discrepancy lifts

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.

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