Leg Length Discrepancy Influences On Running

Overview

Limb deformity or leg length problems can be treated by applying an external frame to the leg. The frame consists of metal rings which go round the limb. The rings are held onto the body by wires and metal pins which pass through the skin and are anchored into the bone. During this operation, the bone is divided. Gradual adjustment of the frame results in creation of a new bone allowing a limb to be lengthened. The procedure involves the child having an anaesthetic. The child is normally in hospital for one week. The child and family are encouraged to clean pin sites around the limb. The adjustments of the frame (distractions) are performed by the child and/or family. The child is normally encouraged to walk on the operated limb and to actively exercise the joints above and below the frame. The child is normally reviewed on a weekly basis in clinic to monitor the correction of the deformity. The frame normally remains in place for 3 months up to one year depending on the condition which is being treated. The frame is normally removed under a general anaesthetic at the end of treatment.Leg Length Discrepancy

Causes

Some causes of leg length discrepancy (other than anatomical). Dysfunction of the hip joint itself leading to compensatory alterations by the joint and muscles that impact on the joint. Muscle mass itself, i.e., the vastus lateralis muscle, pushes the iliotibial band laterally, causing femoral compensations to maintain a line of progression during the gait cycle. This is often misdiagnosed as I-T band syndrome and subsequently treated incorrectly. The internal rotators of the lower limb are being chronically short or in a state of contracture. According to Cunningham's Manual of Practical Anatomy these are muscles whose insertion is lateral to the long axis of the femur. The external rotators of the hip joint are evidenced in the hip rotation test. The iliosacral joint displays joint fixations on the superior or inferior transverse, or the sagittal axes. This may result from many causes including joint, muscle, osseous or compensatory considerations. Short hamstring muscles, i.e., the long head of the biceps femoris muscle. In the closed kinetic chain an inability of the fibula to drop inferior will result in sacrotuberous ligament loading failure. The sacroiliac joint dysfunctions along its right or left oblique axis. Failure or incorrect loading of the Back Force Transmission System (the longitudinal-muscle-tendon-fascia sling and the oblique dorsal muscle-fascia-tendon sling). See the proceedings of the first and second Interdisciplinary World Congress on Low Back Pain. Sacral dysfunction (nutation or counternutation) on the respiratory axis. When we consider the above mentioned, and other causes, it should be obvious that unless we look at all of the causes of leg length discrepancy/asymmetry then we will most assuredly reach a diagnosis based on historical dogma or ritual rather than applying the rules of current differential diagnosis.

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

A systematic and well organized approach should be used in the diagnosis of LLD to ensure all relevant factors are considered and no clues are overlooked which could explain the difference. To determine the asymmetry a patient should be evaluated whilst standing and walking. During the process special care should be used to note the extent of pelvic shift from side to side and deviation along the plane of the front or leading leg as well as the traverse deviation of the back leg and abnormal curvature of the spine. Dynamic gait analysis should be conducted during waling where observation of movement on the sagittal, frontal and transverse planes should be noted. Also observe head, neck and shoulder movements for any tilting.

Non Surgical Treatment

Treatment depends on what limb has the deformity and the amount of deformity present. For example, there may be loss of function of the leg or arm. Cosmetic issues may also be a concern for the patient and their family. If there are problems with the arms, the goal is to improve the appearance and function of the arm. Treatment of leg problems try to correct the deformity that may cause arthritis as the child gets older. If the problem is leg length, where the legs are not "equal," the goal is equalization (making the legs the same length). Treatment may include the use of adaptive devices, prosthesis, orthotics or shoe lifts. If the problem is more severe and not treatable with these methods, then surgery may be necessary.

Leg Length Discrepancy

Surgical Treatment

Shortening techniques can be used after skeletal maturity to achieve leg length equality. Shortening can be done in the proximal femur using a blade plate or hip screw, in the mid-diaphysis of the femur using a closed intramedullary (IM) technique, or in the tibia. Shortening is an accurate technique and involves a much shorter convalescence than lengthening techniques. Quadriceps weakness may occur with femoral shortenings, especially if a mid-diaphyseal shortening of greater than 10% is done. If the femoral shortening is done proximally, no significant weakness should result. Tibial shortening can be done, but there may be a residual bulkiness to the leg, and risks of nonunion and compartment syndrome are higher. If a tibial shortening is done, shortening over an IM nail and prophylactic compartment release are recommended. We limit the use of shortenings to 4 to 5 cm leg length inequality in patients who are skeletally mature.

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