Short leg treatment is no mystery

Conway McLEAN, DPM

Most people obtain much of their medical knowledge from advertisements, gossip, and a host of unreliable sources. For example, it can be seen as amusing how often people don’t know that a problem can occur on only one side of the body. Most know that some internal organs are found on only one side, but many find it surprising that even the extremities can have differences. Sometimes these can be minor and of little clinical significance, while others can lead to a lifetime of pain and problems.

Low back pain is an incredibly common malady in our culture, due to a whole host of reasons. Once again, I am obligated to use the “E” word: epidemic. Back pain is that common. About 80 percent of adults experience low back pain at some point in their lifetimes.

It is the most common cause of job-related disability and a leading contributor to missed work days. In a large survey, more than a quarter of adults reported experiencing low back pain during the past 3 months. How many activities can be performed that don’t involve the back. For example, how about breathing?

Our bodies were not made to spend long hours sitting, nor are they well-suited to walking on hard, flat surfaces the great majority of the time. Variations in the alignment of the legs and pelvis can lead to chronic back pain, which is logical to most.

An unexpectedly frequent explanation for chronic low back pain is a difference in length from one leg to the other. Yet this is so rarely measured, it might almost be seen as a plot. Many individuals go their entire lives, suffering to various degrees, from this terrible affliction, without being thoroughly evaluated for a leg length inequality.

Leg length differences are actually the rule, rather than the exception. Some estimates put the incidence of a leg length difference at 95%. Usually the differences are small, or the body is able to compensate in some fashion. Sometimes no symptoms develop. But frequently the body will develop compensatory mechanisms, which themselves can cause problems, or it is unable to fully make up for the difference.

In either case, symptoms eventually occur with time. Pain will typically be experienced first on the longer leg, and can include a variety of problems. Some common examples are buttock pain, arthritis of the knee or hip, inflammation of a gluteal muscle, tendonitis at the knee cap, patellofemoral pain syndrome, heel pain (plantar fasciitis), shin splints or chronic pain at the ball of the foot (metatarsalgia).

Men and women are equally affected by low back pain, which can range in intensity from a dull, constant ache to a sudden, sharp sensation that leaves the person incapacitated. Pain can begin abruptly as a result of an accident or by lifting something heavy, or it can develop over time due to age-related changes of the spine. Sedentary lifestyles can also set the stage for low back pain, especially when a weekday routine of getting too little exercise is punctuated by a strenuous weekend workout.

Unfortunately, back pain is frequently caused by a structural condition, one which will not resolve over time. Leg length discrepancies are in this category. This abnormality can be caused by poor alignment of the pelvis or simply because one leg is structurally longer than the other. Some children are born with legs that are of unequal length, or there may be bowing of a shin bone.

A length difference may result from how the body is functioning due to some abnormality present at birth. These may alter the alignment of the hips, and change how the structures that make up the leg and pelvis are working together. As you may have gathered, the anatomy is complex, further complicated by how everything is working together.

A variety of conditions can result in low back pain, including such disparate problems as a degenerated or ruptured disc, or a compressed nerve (a radiculopathy). A common condition, termed sciatica, is a nerve compression problem of the sciatic nerve. This pinching causes a shock-like sensation or burning through the buttocks and down one leg, occasionally reaching the foot. In the most extreme cases, when the nerve is pinched between the disc and the adjacent bone, the symptoms may involve not only pain, but numbness and muscle weakness in the leg because of interrupted nerve signaling.

Regardless of the reason, your body wants to be symmetrical and will do its best to compensate for the length difference. One of the most common ways to do that is by shortening the longer leg, and lengthening the shorter. How does it do that? The body has its own “elevator” system, which allows it to jack up the shorter side and lower the longer: it is the arch of the foot.

A frequent finding on an x-ray of the feet, when they are taken with the person weight bearing, is where one arch is lowered and the other raised. This is an obvious clue to the presence of a leg length difference. The individual so afflicted will have no idea why they have this difference, and generally will not even be aware of the asymmetry.

When present for a sufficient length of time, the compensation may develop its own set of problems, even though that is not the true root of the problem. As might be expected, this may cause problems in the foot. Arch or heel pain may result, or stress to particular tendons or joints, and subsequently symptoms from these structures occur. It is not enough to treat the foot pain; recognizing and evaluating limb length discrepancy is necessary for long term relief.

Chronic low back is often treated with anti-inflammatory medication, which does tend to help. If the cause is a transient strain of some of the musculature in the region, this approach may be sufficient. In some, there can be a structural pathology, such as the previously-discussed leg length difference, and so the benefits will not be lasting.

Physical therapy is commonly utilized, and is often beneficial. Appropriate exercises and stretches can help to relieve much of the pain that has developed, yet the benefits will again be transient if the structural difference is not compensated for.

Frequently, a steroid injection is used to treat the inflammation that has developed from the chronic stress to some of the joints of the back or the pelvis. Steroids are powerful anti-inflammatories, and so can produce significant relief of symptoms. Yet again, without addressing the underlying cause of the problem, the benefits are not lasting.

One solution is to surgically lengthen the shorter leg. The science of orthopedics has progressed to the point where we can do this. But this is a very specialized type of surgical procedure, and not commonly performed.

The solution is incredibly simple: a heel lift, which eradicates the need for compensation by the body. How much should be added under the heel is certainly a good question, but that’s where a thorough exam comes into play. Recognizing the cause, with a thorough evaluation, will allow a physician trained in musculoskeletal medicine to determine how much, and how quickly, to accommodate the shorter limb.

If you suffer from chronic low back pain, with pain that continues to recur, you may have a limb length discrepancy. Remember, the solution is simple. So have it checked out; you need your back to do most anything!

Editor’s note: Dr. Conway McLean is a podiatric physician now practicing foot and ankle medicine in the Upper Peninsula, having assumed the practice of Dr. Ken Tabor. McLean has lectured internationally on surgery and wound care, and is board certified in both, with a sub-specialty in foot orthotic therapy. Dr. McLean welcomes questions, comments and suggestions at drcmclean@penmed.com.