Correcting an Anatomical Short Leg Could be the Answer to Chronic Low Back Pain Relief

Low back pain affects 80% of adults at some point in their lifetime and is the primary medical reason for disability and medical expenses. There are many potential causes of low back pain including but not limited to degenerative disc disease, degenerative joint disease, nerve injury/compression, referred visceral pain, disc herniation or bulge, scoliosis, instability, lower extremity pathology and leg-length discrepancy (LLD)[1].

LLD is when one leg is anatomically shorter than the other, frequently causing un-leveling of the sacrum and pelvic called sacral obliquity.  This un-leveling of the spine and pelvic causes stress, strain, and alteration of normal biomechanics.  Alterations in biomechanics cause altered workload on muscles, ligaments, joint capsules, joints, and discs.  The altered biomechanics results in structural changes such as changes in facet joint surfaces, facet arthrosis, bone spurring, disc bulging and compression and secondary and degenerative scoliosis.

A research paper published in the Archives of Physical Medicine and Rehabilitation Conservative correction of leg-length discrepancies of 10mm or less for the relief of chronic low back pain, looked at if correcting leg-length discrepancies of 10mm or less was effective in treating low back pain.  Here are some of the key findings:

“It is suggested that LLD causes asymmetry in the lower extremity joints and in the spine and pelvis, leading to stress and strain with derangement of normal biomechanical function and functional alterations.”

A common result:  “Pelvic obliquity that can be associated with postural or structural scoliosis, which increases the working load exerted on different structures in the back region (e.g. Muscles, ligaments, joint capsule) and on joints and disk.”  A sacral obliquity is one factor that can contribute to scoliosis as well.

“Mild LLD is common, being found in as many as 96% of the adult population”. Yes, you read it right, 96% of the population is found to have a leg-length discrepancy!! Let that sink in!!!

“Discrepancy of 10 mm or less can cause arthritic changes in the lumbar spine.”

Additionally:

• LLD of 9 mm induces a change in the angle of the lumbar facet joints.
• LLD of 6 mm causes pelvic tilt and scoliosis.
• LLD as small as 3 mm will induce postural changes.

“Most patients with a herniated disc have a LLD of 5 mm, and their pain projects to the shorter leg.”  Almost nobody looks for or considers this for patients with disc herniations!!

“The prevalence of low back pain among adults with mild LLD is significantly higher compared with those without LLD.”

Key Point:

“The uniqueness of this study is that LLD was corrected with shoe inserts, as opposed to heel lifts to prevent unnecessary shortening of the Achilles’ tendon.”  Wearing a heel lift is basically like standing on your toes, using a full-length shoe insert is much better.  We always prescribe shoe inserts over heel lifts for this very reason.

This study took 33 patients with chronic low back pain who had an LLD of 10mm or less.  In 22 patients the LLD was corrected with a shoe insert and 11 patients did not receive a shoe insert.  The shoe inserts significantly reduced both pain intensity and disability!!  Patients also reported that the shoe insert was comfortable and did not interfere with their activities of daily living proving that “shoe inserts are noninvasive, inexpensive, and readily available therapeutic measures.”

Summary:  Leg Length Difference (LLD) affects the lumbar spine in the following ways:

1. Causes pelvic obliquity with or without associated lumbar scoliosis.
2. Causes sacroiliac malalignment.
3. Causes a compensatory asymmetry in the work performed by the muscles and ligaments that stabilize the low back.
4. Causes uneven forces in the sacroiliac joints.
5. Causes pathologic changes in the lumbar and sacral spine and in soft tissues.
6. “The asymmetry leads to facet arthrosis, lumbar endplate concavity, wedging of the L5 vertebra, lateral disc compression and other changes all of which may lead to low back pain.
7. Most patients with herniated disks have a leg-length discrepancy of at least 5 mm or more.
8. Shoe insert to the shorter leg can potentially correct these problems.

 

1. Defrin, R., et al., Conservative correction of leg-length discrepancies of 10mm or less for the relief of chronic low back pain. Arch Phys Med Rehabil, 2005. 86(11): p. 2075-80

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