Apparent Leg Length Discrepancy Following Hip Replacement

posted on 27 Apr 2015 01:47 by encouragingjour93
Overview

A difference in the length of your lower and/or upper legs is called a leg length discrepancy. This is fairly common, actually. One study reported that 32 percent of 600 individuals had a difference in their leg lengths ranging from one-fifth to three-fifths of an inch. A person might not even notice if one leg is slightly longer than the other. However, if the difference is not minimal, treatment may be required.Leg Length Discrepancy

Causes

The causes of LLD may be divided into those that shorten a limb versus those that lengthen a limb, or they may be classified as affecting the length versus the rate of growth in a limb. For example, a fracture that heals poorly may shorten a leg slightly, but does not affect its growth rate. Radiation, on the other hand, can affect a leg's long-term ability to expand, but does not acutely affect its length. Causes that shorten the leg are more common than those that lengthen it and include congenital growth deficiencies (seen in hemiatrophy and skeletal dysplasias ), infections that infiltrate the epiphysis (e.g. osteomyelitis ), tumors, fractures that occur through the growth plate or have overriding ends, Legg-Calve-Perthes disease, slipped capital femoral epiphysis (SCFE), and radiation. Lengthening can result from unique conditions, such as hemihypertrophy , in which one or more structures on one side of the body become larger than the other side, vascular malformations or tumors (such as hemangioma ), which cause blood flow on one side to exceed that of the other, Wilm's tumor (of the kidney), septic arthritis, healed fractures, or orthopaedic surgery. Leg length discrepancy may arise from a problem in almost any portion of the femur or tibia. For example, fractures can occur at virtually all levels of the two bones. Fractures or other problems of the fibula do not lead to LLD, as long as the more central, weight-bearing tibia is unaffected. Because many cases of LLD are due to decreased rate of growth, the femoral or tibial epiphyses are commonly affected regions.

Symptoms

Many people walk around with LLD?s of up to 2 cm. and not even know it. However, discrepancies above 2 cm. becomes more noticeable, and a slight limp is present. But even up to 3 cm. a small lift compensates very well, and many patients are quite happy with this arrangement. Beyond 3 cm. however, the limp is quite pronounced, and medical care is often sought at that point. Walking with a short leg gait is not only unsightly, but increases energy expenditure during ambulation. It could also put more stress on the long leg, and causes functional scoliosis. Where the discrepancy is more severe, walking becomes grotesque or virtually impossible.

Diagnosis

Asymmetry is a clue that a LLD is present. The center of gravity will shift to the short limb side and patients will try to compensate, displaying indications such as pelvic tilt, lumbar scoliosis, knee flexion, or unilateral foot pronation. Asking simple questions such as, "Do you favor one leg over the other?" or, "Do you find it uncomfortable to stand?" may also provide some valuable information. Performing a gait analysis will yield some clues as to how the patient compensates during ambulation. Using plantar pressure plates can indicate load pressure differences between the feet. It is helpful if the gait analysis can be video-recorded and played back in slow motion to catch the subtle aspects of movement.

Non Surgical Treatment

Treatment depends on the amount and cause of the leg length discrepancy as well as the age of your child. Typically, if the difference is less than 2 cm we don?t recommend immediate treatment. We may recommend that your child wear a heel lift in one shoe to make walking and running more comfortable. If the leg length discrepancy is more significant, your doctor may recommend surgery to shorten or lengthen a leg. The procedure used most often to shorten a leg is called epiphysiodesis.

Leg Length

Surgical Treatment

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.