Leg length difference (LLD) is primarily when the hips are not level, causing a limp from side to side. Most practitioners divide LLD into anatomical or functional. Anatomical is when there is a true difference in the length of the tibia/fibula or the femur bone, or both. While functional LLD are either the shortening or lengthening of a limb, secondary to joint contracture or muscle imbalances.
LLDs are very common. Sometimes the cause isn?t known. But the known causes of LLD in children include, injury or infection that slows growth of one leg bone. Injury to the growth plate (a soft part of a long bone that allows the bone to grow). Growth plate injury can slow bone growth in that leg. Fracture to a leg bone that causes overgrowth of the bone as it heals. A congenital (present at birth) problem (one whole side of the child?s body may be larger than the other side). Conditions that affect muscles and nerves, such as polio.
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.
There are several orthopedic tests that are used, but they are rudimentary and have some degree of error. Even using a tape measure with specific anatomic landmarks has its errors. Most leg length differences can be seen with a well trained eye, but I always recommend what is called a scanagram, or a x-ray bone length study (see picture above). This test will give a precise measurement in millimeters of the length difference.
Non Surgical Treatment
People with uneven leg lengths may be more prone to pain in their back, hips, and knees; uneven gait; and lower leg and foot problems. Due to its risks, surgery is typically not recommended unless the difference is greater than one inch. In cases where the difference is less than one inch, providing the same support for both feet is the most effective. This can be achieved by getting custom-fitted orthotics for both feet. Orthotics are inserts that you wear in the shoes. Your chiropractor will request to measure your feet and possibly your legs. You can step on a device that will take the measurements or you might have a plaster cast of your feet taken. Orthotics are typically made from plastic and leather, and function biomechanically with your foot. If a leg length discrepancy is not properly corrected with orthotics, your chiropractor may recommend a heel lift, also known as a shoe lift. You simply place it in the back of your shoe along with the orthotic. Typically, you will only wear the heel lift in one shoe to assist the shorter leg.
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.