Instep Dance Magazine Articles
Reprints of monthly column as first appearing in Instep Dance Magazine.
Are You Lopsided?
By Rick Allen, DC
Well, dancers, have you taken care of your bruises, blisters, tendonitis and sprains? This month, let's look at a more long term challenge -- the impact of leg length differences on your dancing and overall health.
More people than you might expect have a short leg. The problems they experience may be pain in the feet, legs, knees, hips, low back, all the way to the upper back and neck. Even headaches may be related! What ever you call it -- short leg syndrome, leg leg difference, leg length inequality, or LLI -- it is quite common and can have surprisingly profound effects. Let's take an overview of the incidence, causes, effects, examination and (next month) treatment of LLI. If you have such a problem, you will probably be able to correct it, or at least manage it, thereby improving your dancing performance.
Researchers differ in their methods of measuring leg length and their opinions as to the amount of leg length inequality which is clinically significant. In various studies, researchers have found 10 to 48 per cent of the individuals to have LLI of 5 to 10+ millimeters (mm). Although some people experience problems with LLI of only a few millimeters, differences of 5 mm (2/10 inch) or more are generally considered clinically significant. That is, they cause problems.
Studies of symptomatic people show significant correlation between LLI and mechanical back pain. In one study of 1000 soldiers with backache, 77 per cent had an average of 7 mm LLI, and a difference of 5 mm or more was significantly correlated with symptoms and disability. With a difference of 5 mm or more, you are two to three times as likely to have a related problem.
LLI can be categorized as structural or functional. Structural LLI is a true difference in the length of the legs, perhaps due to unequal growth rates, fractures, deformities or altered joint structure. Functional LLI results from excessive foot pronation (flat feet), muscle contractures or pelvic distortions.
Both types of LLI result in tilting the pelvis toward the short leg side and a compensating curvature of the lumbar spine. A LLI of 5 mm can be critical, perpetuating trigger points in the muscles of the pelvis, such as the psoas and piriformis, and back, such as the quadratus lumborum and paraspinals. As a dancer, you may notice foot, leg or back pain as the evening wears on. Long term, this can cause changes in the bones, such as spurs. Your shoes will wear abnormally, too. LLI can be a cause for scoliosis in growing children. Severe scoliois can lead to cardiopulmonary complications that can shorten life span.
The body's efforts to maintain balance in the presence of a short leg can cause a loss of energy. It has been documented that more oxygen is used by individuals with LLI and that shoe lift therapy could improve oxygen consumption. Could this contribute to your being overly tired?
Compensatory mechanisms disrupt the gait cycle of the foot's subtalar joint and, due to the altered timing sequence and overworked extrinsic musculature, may subject a dancer to injury. A recent study found that LLI of about 1/2 inch created changes in bones that precede stress fractures. These changes were visible on magnetic resonance imaging (MRI) in just two weeks after the normal subjects had a lift added to their shoe for the test. The changes went back to normal when the leg lengths were made equal.
Studies have also shown knee injuries to be more common in high school athletes with LLI. Often times this is due to excessive pronation or flattening of the arch of the foot, accompanied by excessive outward rotation of the foot, ankle, knee and hip. (As an aside, excessive outward rotation of the foot, also called foot flare or toe out, can make the difference in who wins a race - a 25 degree flare results in losing up to half a mile in a marathon.)
If the myofascial pain syndrome is treated without correcting the causes of physical stress, the patient is doomed to endless cycles of treatment and relapse. On the other hand, eliminating the causes of the stress can result in complete relief of the pain. For example, in a study of 63 obstetric patients with unequal legs, 53 complained of low back or flank pain and 90% were relieved with heel lifts.
So, LLI can have surprisingly wide ranging effects. You better get checked out!
A trained professional will examine your posture for symmetry, often using a plumb line or reference frame for more accuracy. They will take a measurement of your leg length, either from the front of the pelvis to the ankle bone (malleoli) or by comparing the position of your heels or shoes while lying face down. They will compare the length of your femur and tibia of each leg.
Conducting a biomechanical screening of your lower extremities, they will look for five "red flags":
- foot flare different from the normal 5 to 10 degrees,
- unusual wear of your shoes -- excessive pronation will result in greater wear on the outer edge of the heel,
- medial facing patellae -- "squinting" knee caps,
- medial bowing of the Achilles tendons, and
- lack of the medial arches or painful plantar fascia.
They will palpate spine, looking for tenderness, altered temperature, muscle spasm, and altered joint play. They will test reflexes, skin sensation, and muscle strength, which may indicate nerve involvement.
Taking you into action, they will evaluate your gait, looking for smooth, symmetrical body motion, a normal even stride, and proper alignment of the knee, ankle and foot. They may use a treadmill to evaluate your gait, but oftentimes a sufficient clinical picture can be obtained by just observing you walk or run.
If the problem is severe or difficult to treat, the doctor may take an x-ray. The most accurate way to determine LLI is by radiographic examination, so they may take an x-ray of your pelvis while you stand barefoot. Later they may take a comparison film with you wearing a corrective lift or orthotic.Error processing SSI file
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