Hereditary Leg Length Discrepancy

Overview

Having one leg shorter than the other is a common physical condition. It has two primary causes--structural or functional problems. Structural differences in length can be the result of growth defect, previous injuries or surgeries. Functional differences in length can result from altered mechanics of the feet, knee, hip and/or pelvis. These altered mechanics from functional leg length discrepancy often stem from having an unbalanced foundation.Leg Length Discrepancy

Causes

There are many causes of leg length discrepancy. Structural inequality is due to interference of normal bone growth of the lower extremity, which can occur from trauma or infection in a child. Functional inequality has many causes, including Poliomyelitis or other paralytic deformities can retard bone growth in children. Contracture of the Iliotibial band. Scoliosis or curvature of the spine. Fixed pelvic obliquity. Abduction or flexion contraction of the hip. Flexion contractures or other deformities of the knee. Foot deformities.

Symptoms

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.

Diagnosis

The doctor carefully examines the child. He or she checks to be sure the legs are actually different lengths. This is because problems with the hip (such as a loose joint) or back (scoliosis) can make the child appear to have one shorter leg, even though the legs are the same length. An X-ray of the child?s legs is taken. During the X-ray, a long ruler is put in the image so an accurate measurement of each leg bone can be taken. If an underlying cause of the discrepancy is suspected, tests are done to rule it out.

Non Surgical Treatment

Treatment for an LLD depends on the amount of difference and the cause, if known. The doctor will discuss treatment options carefully with you and your child before any decisions are made. It is important to note that treatment is planned with the child?s final height and leg lengths in mind, not the current leg lengths. Treatment is generally not needed if the child?s final LLD is predicted to be 2 centimeters or less at full height. However, the child should return to an orthopaedic doctor by age 10 for re-evaluation. Treatment is often recommended for LLDs predicted to be more than 2 centimeters at full height. If treatment is done, it usually doesn?t begin until the child starts walking. Possible treatment options include, A ?lift? in one shoe to level the child?s hips. This is often the only treatment needed for small discrepancies.

LLD Shoe Inserts

Surgical Treatment

Surgical options in leg length discrepancy treatment include procedures to lengthen the shorter leg, or shorten the longer leg. Your child's physician will choose the safest and most effective method based on the aforementioned factors. No matter the surgical procedure performed, physical therapy will be required after surgery in order to stretch muscles and help support the flexibility of the surrounding joints. Surgical shortening is safer than surgical lengthening and has fewer complications. Surgical procedures to shorten one leg include removing part of a bone, called a bone resection. They can also include epiphysiodesis or epiphyseal stapling, where the growth plate in a bone is tethered or stapled. This slows the rate of growth in the surgical leg.

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