Leg Length Differences-Does it Matter?

By David Coletta, MPT, CMPT
david@excelptmt.com

There is no doubt that leg length differences (LLDs) exist, but a lack of agreement exists about diagnosing the condition, their functional importance, and how to treat them.  How many of us have been to the physical therapist, massage therapist, or chiropractor and were told that our legs were not of equal length?  Lying face up on the exam table, we ponder what to do about this recent revelation.

Most experts agree that 0.5 centimeters (1/8 inch) or less of leg length difference is not significant.  Furthermore, most clinicians agree that mild to modest discrepancies should not be corrected in the absence of pain or dysfunction.  If it doesn’t hurt, then don’t fix it.  But what if the difference is causing problems?  How reliable is a clinician’s assessment of your LLD?

LLDs can be either anatomical or functional.  An anatomical LLD is present because of a structural (bone; cartilage) difference, comparing one leg to the other.  For example, an individual may have broken a bone in his or her leg at a young age, creating a disturbance in the growth plate, ultimately leading to an alteration in that bones final, mature length.  A functional leg length occurs when a limb only presents longer or shorter because of being forced into this position by changes in muscles or other soft tissues of the low back, hips, or feet.   Tight muscles in the right side of your low back can draw up the right leg, making it present as shorter. 

Clinically, physical therapists can pick up a LLD by looking at your leg lengths in standing and lying down with the use of visual inspection and tape measurement.  There have been several studies looking at the accuracy of LLD clinical assessment and the evidence seems to point towards our ability in picking up these discrepancies.  However, clinical accuracy is limited.  I can say “Mrs. Jones, your left leg is around 1 to 1.5 centimeters longer on the right.”  I cannot say “Mrs. Jones, your left leg is exactly 1 centimeter longer on the right.”  Only obtaining an x-ray or CT-Scan of the legs can give you a fairly accurate number on LLD.

Most of us are walking around with some type of LLD, which is more likely functional, rather than anatomical.  Don’t be surprised if someday you are told that one leg is longer or shorter than the other.  In the presence of pain, a LLD can be addressed by placing a heel lift in the shoe or adding to the sole on the outside of the shoe.  Use caution when correcting a LLD.  A good rule of thumb is to correct for no more than ½ of the suspected LLD and only make an alteration of 3 to 5 millimeters at one time.  Wait several weeks to month a month before trying additional lift height.  Your physical therapist or other health care professional can assist you in this process.

To reach David Coletta, MPT, CMPT with any LLD questions, please contact him at “david at excelptmt dot com” or call our Excel Physical Therapy Bozeman office at 406.556.0562.

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