One is not like the other: Leg-length inequality

One is not like the other: Leg-length inequality

“Just long enough to reach the ground,” Abraham Lincoln famously replied to the question, “How long should a man’s legs be?” But what if the right leg reaches the ground sooner than the left one does? It happens more often than most people might think. Disparities in leg length, in fact, may be relatively common: a study published in Spine in 1983 found that 43.5 percent of people with no back pain symptoms had leg-length inequality of five millimeters or more, while a whopping 75.4 percent of study subjects with chronic low-back pain had similar leg-length discrepancies.

“Leg-length inequality is a significant factor in chronic low-back pain. But it’s associated not only with lumbar spine pain but hip joint pain, as well,” says Leo Bronston, DC, who practices in La Crosse, Wisconsin, and serves as vice president of the ACA’s Council on Orthopedics. “It can also affect the knee, but most of the time you’re going to find that a patient will have chronic lower-back pain and hip pain.”

In the hip area, the leg that is longer carries more weight, making it vulnerable to abuse in weight-bearing activities like walking or running. “Long-standing leg-length inequality has been shown to lead to hip joint arthritis. There are some studies on that, but they aren’t indexed studies,” says Dr. Bronston.

Despite its apparent prevalence, leg-length inequality is all too often overlooked in diagnosing chronic back and hip pain. “Experts in the field will tell you that anyone suffering from chronic back, hip, knee, or leg pain should be evaluated for leg-length inequality,” Dr. Bronston says. “It should be a standard rule out.”

When one leg is shorter than the other, you may be dealing with either a functional leg-length discrepancy, which can often be completely corrected by manipulation, or an anatomical leg-length discrepancy, which is a permanent leg-length deficit.

Functional discrepancies, explains Dr. Bronston, have a variety of causes. “You can have muscle spasms in one hip; you can have hip capsule tightness; you can have adductor muscle spasm on one side; and you can have pronation of one foot and supination of the other foot. Those are the main sources of a functional disparity,” he says.

“Anatomical discrepancies also stem from a variety of sources,” says Henry West, DC, an ACA state delegate representing Idaho. “There can be a difference in the length of the femur or the tibia, for example. Also, if the patient has had knee surgeries or ankle injuries or fractures, that can lead to leg-length discrepancies.” Polio and other disease processes, says

Dr. Bronston, can also render one leg shorter than the other.

The effects of leg-length discrepancies, Dr. West says, can often be seen in the quirks of an athlete’s performance. “My father used to treat a lot of the baseball players for the Class D Pocatello Cardinals, and was very good friends with the coach,” he recalls. “If a right-handed ballplayer was consistently hitting pop flies, often we’d find that his right leg would be short-so when he’d swing, he’d be undercutting. If his left leg was too short, he’d be hitting ground balls because he was overcutting.” Much the same thing happens in other sports, like basketball and golf. “If your right leg is short and you tend to shoot off the right leg, even though you’re a jump shooter, you’ll fall short and hit the rim instead of putting it through the hoop,” Dr. West says. “If you’re a golfer, you’re not going to hit the ball where you’re aiming it because of a shift of the pelvis, which may relate to a functional or an anatomical short leg.”

A Functional or Anatomical Problem?

Many of us may have these leg-length disparities and never notice them, like the study subjects in the Spine article who had no low-back pain. “It’s clinically significant when you have symptoms,” says Dr. West, and at that point, the DC must determine the extent of the leg-length discrepancy and its origins. This involves a combination of clinical and radiographic examination. “The mainstay is the clinical examination; that’s going to give you most of the information. A radiographic exam will confirm a leg-length deficiency when clinically correlated,” Dr. Bronston adds.

To assess an actual (rather than a functional) leg– length disparity, the chiropractor should measure from a landmark on the pelvis – usually the anterior superior iliac spine – out to the medial maleolus, and then compare each side. Dr. West advises placing the patient on a high-low table, without shoes, for this measurement. “Experts will tell you that an eighth of an inch to a quarter inch could be a physiological `normal,'” Dr. Bronston says. “There can be some variables, including examiner error or the technique of the measuring. But anything over about 3/16 of an inch, or five millimeters, is clinically significant, and it can definitely affect the outcomes of your patient’s pain.”

“In many cases, your patients may be already aware of the problem. Many times you can adjust the patient and it takes care of itself, maybe with just a shift of a sacroiliac joint, but if it’s not holding, you need to look at a heel lift or an orthotic shoe.”

In some patients, particularly the elderly, hip and knee replacements can lead to anatomical leg– length discrepancies. “We see a lot more patients today who’ve had knee and hip replacements, and the majority of them do present with leg-length inequality that sometimes is the source of their chronic low-back pain,” says Dr. Bronston. “The joint is replaced and the hip and knee pain goes away, but then the patient may start presenting with low-back pain due to inequality in the limbs because of the replacement. Although surgeons try to make sure the leg with the replacement is of the same length as the other, there’s no guarantee. After surgery, muscular imbalances can change, so follow-up with these patients is important.”

Treatment for the Long Term

Treatment of chronic low-back pain or knee pain that stems at least in part from leg-length inequality is a two-step process, Dr. Bronston says. “The first consideration is spinal manipulation to reduce the misalignments and muscular tightness within the lower back and pelvis, which are normal occurrences with leg-length inequality. The second would be utilization of a heel lift under the short-leg side to stabilize and level the pelvis. A lift gives the spine a more level foundation on which to rest, reduces stress on spinal joints and distortions of the vertebrae, and normalizes muscular balance.” In fact, he believes that 75 percent of patients with low– back pain would find their symptoms normalized by this process. “Hip pain treatment would use the same two-step process, although I would work more on the musculature of the pelvis and hip using some direct exercises of flexibility, either passive or active, in order to increase some of the flexibility of the hip joint. That would be the only difference.”

Heel lifts may not be necessary for the patient with a functional leg-length inequality, which can in many cases be remedied fully by manipulation. “But if there’s an anatomical inequality, there are going to be recurrent problems without a shoe lift or a shoe correction,” Dr. West says. “Probably two to four times a week in my practice alone, I’ll have a patient say, ‘I had no idea that was causing so much of a problem! I feel so much better since you put that lift in.'”

Heel lifts don’t have to completely correct the discrepancy in order to achieve these results. “Let’s say there’s a half-inch deficiency in a standing x-ray of the right femoral head, as compared to the left femoral head,” Dr. West says. “When creating the lift, make it one-half to maybe two-thirds of the difference, and it works out fine.” Dr. Bronston agrees, and both note that extreme discrepancies will require a lift in the sole, as well as the heel. “If the leg-length difference is greater than a half inch, then you have to build the sole up, as well. For some patients, you may have to not just provide a heel lift, but also have a cobbler add to the sole so they’re not tripping over their toes,” Dr. Bronston says.

Although the heel lift corrects the problem, chiropractic manipulation will speed the recovery process. “You can just assume that these patients will be treated with manipulative therapy for the nominate distortion pattern, electrical stimulation for the muscle rehabilitation, and ultrasound,” Dr. West says. “And they get over their pain much faster with this combination of treatment and therapies than just with the heel lift alone. But then they continue with the heel lift as a correction.”

Some patients are recalcitrant about permanently adding lifts to their footwear wardrobe. “I wear glasses. I wish I didn’t have to, but it’s sure better than the alternative,” Dr. West says. “A lot of people only want to wear a heel lift a month or two to get relief, but it doesn’t work that way. You need to keep wearing it. When you forget the heel lift, or your corrective shoe, then you’re more likely to get symptoms back. After two or three recurrences, people usually learn.”

“We walk on the foundation of our feet. We’re not suspended by sky hooks,” Dr. West comments. “Doctors of chiropractic should realize that leg length is very important as it relates to the balance of the pelvis and the structural stress that is a consequence of leg-length inequality.”

Copyright American Chiropractic Association Feb 2003

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