Leg Length Discrepancy Tests

Overview

The two major categorizations of LLD are structural and functional. A third more minor category is environmental. In structural LLD there is an actual anatomical difference in the bones of the lower extremities where one side becomes shorter than the other. This type of LLD may be genetic, where the person is born in this way. In other cases it may be due to injury or infection through the growth phases of early childhood or adolescence. Some spinal abnormalities like scoliosis can also cause this condition. Functional LLD is where the bones are not the cause of difference but a muscle or pelvic condition has the effect of weakening the leg on one side. Conditions that can cause this are muscle inflexibility, adduction contractures and pelvic obliquity (amongst others). The third less severe category of environmental LLD is caused by discrepancies in the surface that the feet and legs are resting or walking on. Banked, uneven or curved surfaces can all cause environmental LLD. In LLD the asymmetric nature of the legs in relation to hips and back caused the centre of gravity to shift from its natural position. This then results in the body attempting to compensate by either tilting the pelvic areas towards the shorter side, increased knee flexing on the longer side, flexion of the ankle plantar and foot supination towards the shorter side.Leg Length Discrepancy

Causes

Leg length discrepancies can be caused by poor alignment of the pelvis or simply because one leg is structurally longer than the other. Regardless of the reason, your body wants to be symmetrical and will do its best to compensate for the length difference. The greater the leg length difference, the earlier the symptoms will present themselves to the patient. Specific diagnoses that coincide with leg length discrepancy include: scoliosis, lumbar herniated discs, sacroiliitis, pelvic obiliquity, greater trochanteric bursitis, hip arthritis, piriformis syndrome, patellofemoral syndrome and foot pronation. Other potential causes could be due to an injury (such as a fracture), bone disease, bone tumors, congenital problems (present at birth) or from a neuromuscular problem.

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

A doctor will generally take a detailed medical history of both the patient and family, including asking about recent injuries or illnesses. He or she will carefully examine the patient, observing how he or she moves and stands. If necessary, an orthopedic surgeon will order X-ray, bone age determinations and computed tomography (CT) scans or magnetic resonance imaging (MRI).

Non Surgical Treatment

In some circumstances, the physician will recommend a non-surgical form of treatment. Non-surgical treatments include orthotics and prosthetics. Orthotics are a special type of lift placed in or on a shoe that can be used in the treatment of leg length discrepancies between two and six centimeters. In pediatric patients who have large discrepancies and are not good candidates for other treatment forms, prosthetics can be helpful.

Leg Length

shoe lifts for men's shoes

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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