Apparent Leg Length Discrepancy Causes

Overview

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.

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

Often there are few or no symptoms prior to the age of 25-35. The most common symptom is chronic lower back pain, but also is frequently middle and upper back pain. Same-sided and repeated injury or pain to the hip, knee and/or ankle is also a hallmark of a long-standing untreated LLD. It is not uncommon to have buttock or radiating hip pain that is non-dermatomal (not from a disc) and tends to go away when lying down.

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 of leg length inequality involves many different approaches, which vary among osteopaths, physiotherapist and chiropractor and whether the LLD is functional or structural. Thus is a combination of myofascial release (massage) & stretching of shortened muscles. Manipulation or mobilization of the spine, sacro-iliac joint (SIJ), hip, knee, foot. Orthotics, shoe lifts can be used to treat discrepancies from two to six cm (usually up to 1 cm can be inserted in the shoe. For larger leg length inequalities, the shoe must be built up. This needs to be done for every shoe worn, thus limiting the type of shoe that the patient can wear). Surgery (epiphysiodesis, epiphyseal stapling,bone resection).



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.