People with leg length discrepancy, when one leg is longer than the other, usually have a waddling-type gait where the hips seem to move up and down during walking as the body tries to compensate for the inequality. There are two types of leg length discrepancy. The first type of leg length discrepancy involves a structural defect, where one bone is longer or shorter than the corresponding bone of the other limb. This can occur within the femur (upper leg bone) or the tibia and fibular (lower leg bones). Functional leg length discrepancy results from altered mechanics due to a malalignment in the spine or lower extremity.
Leg length discrepancies can be caused by: hip and knee replacements, lower limb injuries, bone diseases, neuromuscular issues and congenital problems. Although discrepancies of 2 cm or less are most common, discrepancies can be greater than 6 cm. People who have LLD tend to make up for the difference by over bending their longer leg or standing on the toes of their shorter leg. This compensation leads to an inefficient, up and down gait, which is quite tiring and over time can result in posture problems as well as pain in the back, hips, knees and ankles.
In addition to the distinctive walk of a person with leg length discrepancy, over time, other deformities may be noted, which help compensate for the condition. Toe walking on the short side to decrease the swaying during gait. The foot will supinate (high arch) on the shorter side. The foot will pronate (flattening of the arch) on the longer side. Excessive pronation leads to hypermobility and instability, resulting in metatarsus primus varus and associated unilateral juvenile hallux valgus (bunion) deformity.
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.
what is a shoe lift?
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.