Persistent low back pain is complicated and difficult. One of the most common clinical findings I see with persistent low back pain is an undiagnosed leg length discrepancy (LLD). Basically, one leg is longer, either structurally or functionally, and produces strain in the low back that is bothersome in standing and walking activities. It’s usually the long side that is painful in most cases, with the shorter side rarely having problems.

LLD has been a source of controversy in the medical community and correcting LLDs for Low Back Pain have fallen in and out of favor several times in the last 100 years. My mother, for example, had a leg that was ¾ inch longer. She had to go outside the medical community in the 1950s to have somebody who would correct it, but they fixed it when she had her total hip replacement in 2012.

I have worked with many providers who argue back and forth on this topic, and you will find many different opinions of what is the best way to manage, if at all, these conditions. I actually was scolded once by a fellow colleague when I was a novice clinician for even wanting to address a LLD with a client. (“they don’t exist and inserts don’t work”)

When I perform my initial exam on the first visit, I will always look at leg length. Over the years, I’ve gotten pretty good about how to do this consistently and reliably

There are three kinds of leg length discrepancies:

  • Uncompensated: LLDs are straight forward problems with no compensation in the surrounding joints. A common one I see is a patient that has a total knee or total hip replacement and the leg, as a result of the surgery, is either shorter or longer.
  • Compensated: LLDs are where the increase length of bone cause some other dysfunction in the joints to compensation for the increased height and try to get some kind of symmetry to the body.

Compensated LLDs can be broken down into two categories:

  1. LLDs that hide in the low back and pelvis. From my experiences, this is more common in female patients.
  2. LLDs that hide in the foot. From experience, this is more common in male patients.

A third potential category is functional LLDs which is a problem where there is technically no structural LLD, but one leg is short due to a knee flexion contracture or a foot deformity.

Because the body has a funny way of fooling clinicians, I usually like to see the same distance on the same side at least two to three visits so I can assure there is truly a LLD that needs to be addressed.

The simple way to deal with LLDis to add something to make the legs even. The most traditional device is called a heel lift with can be placed in a shoe and the most common product is called an Orthoheel. However, I have had much more success with a full length insert that I make with some special material that I order from Germany. It has less stress of the metatarsals (bones in your feet) and feels more natural to walk or run.

Large LLDs are hard to make a quick insert that fits in the shoe. 4-6mm can sometimes be manageable with an insert, but anything bigger than 6mm always requires an external lift on a shoe as adding material changes the volume of the shoe and can sometimes cramp the toe and cause pain.

The difficult aspect of LLDs is that adding material to the short leg is only one part of the problem. In some cases, back pain quickly goes away with adding material. In other cases, addressing the LLD is only one part of a complete treatment program.

Case Study:

65 year old male, retired CEO, presented to the clinic with persistent low back pain on the right side. He had previous injections that did not offer any long term improvement and failed prior physical therapy at a dedicated spine physical therapy clinic. He was recommended to have a surgery, but was really trying to avoid any additional procedures.

We identified a moderately large LLD on the right side that was about 10-11mm. He was very reluctant to use a full length insert initially, but he was eventually convinced to try a trial period to use it on a consistent basis. We added 6mm to the left shoe to see if this would affect his pain. Over the course of a long weekend, 90% of his pain was resolved with consistent use of the insert. He was discharged with full resolution of his symptoms in 6 visits. The treatment plan consisted of a strong lumbar stabilization program, manual therapy to address lumbar and pelvic joint problems, and patient education on how to manage his low back pain and avoid a future event of low back pain.