BackFix Tips from Dr. Jeff Keysar, DC

The Most Overlooked Cause Of Lower Back Pain

Back pain is extremely common. As we already know, it’s a condition that most of us will face at some point during our lifetime. And as you’ve probably seen, there is no shortage of pills, rubs, shots, and treatment devices available to manage back pain.

However, the majority of back pain treatments do nothing to address WHY someone has back pain. These treatments only seek to reduce the symptoms felt by the patient instead of eliminating the source of those symptoms.

Since we are bipedal creatures — meaning, we walk upright on two feet — it’s vital we have a level foundation for our spine to rest on. By default, this means our pelvis must be level, which means our legs must be of equal length when standing up barefooted on a level surface. (See figure below)

Due to the inherent nature of our bodies, we aren’t perfectly symmetrical from one side to another. You might notice this on yourself, or when looking at other people, how, perhaps, one ear may look slightly lower than the other, or one eye might be slightly smaller or larger than another. On women, it’s not unusual sometimes for one breast to be larger than another or for one to be positioned lower than the other. These variances are extremely common, but most are simply not big enough to be seen with the naked eye.

So what happens when someone has a difference in length on one leg versus the other? The result is an unlevel pelvis when that person is standing or walking. The pelvis will tilt downward on the lower leg side, which causes the lower spine to lean in the same direction. It’s common, then, for the rest of the spine to begin to bend back the other direction away from the short leg side in an attempt to find postural balance. This can result in what’s known as a postural scoliosis.

In a postural scoliosis, there are uneven forces being placed on the muscles, joints and discs. And while the body may be very good at compensating for these forces over the short term, long term imbalanced forces allow the degenerative aging process to be accelerated, causing premature wear and tear responsible for many of the aches and pains patients see us for. In effect, staying in a crooked position for extended periods of time causes your muscles, joints, and discs to age rapidly and become older than the rest of you.

Knowing this, we must then evaluate leg length inequality in chronic lower back pain cases whenever possible. The average person has a leg length difference of approximately 3 millimeters, while back pain sufferers with leg length inequality will often have a difference of 6 millimeters or more. The most severe case of leg length difference I have seen in practice was an 18 year old female in excellent physical condition except for the lower back pain she suffered from.

After x-ray analysis, it was determined that one of her legs was 36 millimeters shorter than the other. That’s about an inch and a half! To know what that felt like, go find one of your shoes that has a sole thickness of about an inch and a half, put it on, but leave the other shoe off. Now walk for five minutes. That crazy, crooked and twisted feeling you’d experience is what her young spine had gotten used to.

Whenever leg length inequality is suspected, a standing lumbar x-ray that shows the hip joints is necessary to determine the actual amount of difference. Some health care providers opt for an eyeball measurement of the leg length difference by simply checking visually if one leg is longer than the other while the patient is laying down on a table. Some PTs and even some MDs have been taught to use a tape measure to evaluate the length from the bony point at the front of the hip to the outside edge of the ankle and comparing each side. Both this and the “eyeballing it” method are extremely error prone and not accurate enough to determine a measurement for treatment. Only the standing x-ray, done properly, has enough accuracy to observe the actual amount of leg length difference. Functional leg length differences- caused by tight or spasmed muscles and often evaluated with a face-down leg check - will cause an artificial leg length difference that can "appear" to improve after an adjustment, but this method is unreliable as a means to determine true, real leg length differences.

Once the leg length difference has been identified, a rubber heel lift is usually given to the patient to wear in their shoe. This heel lift raises the short leg side up so that it matches the length of the other leg, essentially balancing the pelvis and providing a level base for the spine to rest on. In cases where the leg length difference is 12 millimeters or less, a heel lift is the preferred method of leveling the pelvis. When the leg length difference is more than 12 millimeters, a sole lift on the entire shoe is recommended to correct the first 12 millimeters. The sole lift is preferred over the heel lift alone because lifting the heel more than 12 millimeters causes excessive strain on the ankle joint that can be avoided by lifting the entire shoe.

Once the first 12 millimeters is corrected with a sole lift, any remaining difference can be finished with a heel lift. Of course, the entire amount of leg difference can be corrected with only a sole lift, but many people opt for the smallest sole lift possible so their shoe modification isn’t so obvious when they’re out in public. Personal preference plus the doctor’s recommendation will determine the right course of action.

I call leg length difference the most common overlooked cause of back pain because that’s exactly the case. So many health care providers focus on immediate pain relief via spinal manipulation, massage, electrical stimulation, ultrasound, traction, stretching, and exercises. And while these modalities are all excellent when it comes to pain relief, the end result of their use is a flexible, pain free but imbalanced spine that, given enough time, will build up enough wear and tear to start the pain cycle all over again or cause a greater risk of injury when performing normal daily tasks. Correcting any structural deficiencies caused by a leg length difference is the best way to ensure that gravity places minimal forces on our backs and we are maximizing the useful life of our discs, muscles, bones and joints.