The vast majority of neck and lower back pain occurs idiopathically, meaning there is no known cause. In these cases, people were not involved in a car accident, they didn’t slip and fall, their pain simply just started happening. In the past, although most of these people got great results from chiropractic care, there was a small number that felt better after their treatments, but didn’t feel like their adjustments lasted for long periods. Recently we have determined that many of these problems were the result of having a leg length discrepancy, meaning they had one leg that is longer, or shorter, than the other.
What is Leg Length Discrepancy?
If there is a difference of 3 mm or more between the length of your legs, the difference is considered significant. A difference of 1 or 2 mm is not likely to cause many problems. This discrepancy between leg lengths can either be anatomical or functional.
Anatomic Leg Length Discrepancy
An anatomic leg length discrepancy is defined as having either one, or both, bones of the leg measuring shorter than the other. This can be the result of either having the bones naturally grow different lengths, or in some cases can be the result of a prior fracture or other injury.
Functional Leg Length Discrepancy
A functional short leg occurs when there is no anatomical difference between legs, meaning the bones are the same length. Functional short legs are usually the result of pelvic misalignments or muscle imbalances between legs. A functional short leg is usually the result of long term daily activity that is unbalanced.
Can You Have Both?
Yes, absolutely. In cases where patients have an anatomic short leg, we usually find that they also have a functional component as well. In this case, both the functional and anatomic short legs are treated, and great results are obtained.
How Do You Know if You Have A Leg Length Discrepancy?
An anatomic leg length can only truly be determined by taking a specific set of x-rays. This consists of an x-ray at the hips, knees and ankles. Measurements are then made of the femur, the upper leg bone, and tibia, one of the lower leg bones, to determine if there is a difference between the left and right leg. If there is a difference of 3 mm or more, the presence of an anatomic short leg is verified. For more information on leg length x-rays, click here.
If there is a difference of less than 3 mm on this x-ray, a functional leg length discrepancy is still possible. A functional leg length discrepancy can be determined through a thorough examination, and a pelvic AP (front to back) x-ray.
What Are The Effects of Having a Short Leg
The most common effect of having a short leg is lower back pain, usually in the sacroiliac (SI) joints. Other common effects of a short leg are sciatica, knee and ankle/foot pain. Since a short leg often affects the pelvis, which is the foundation of the spine, it can also lead to pain in other areas of the spine, such as the neck and upper back.
Treatment of Leg Length Discrepancy
A functional leg length can often be corrected with a combination of chiropractic adjustments and stretching. The chiropractic adjustments will properly align the pelvis, which may be the cause of the leg length difference. Stretching, especially the hamstrings and hip rotators, can also help correct any muscular imbalance that led to the pelvic misalignment. In addition, altering the daily activities that caused the problem is important. Adjustments will not be as effective if you continue to do the same thing over and over that caused the misalignments in the first place. You can find more information on chiropractic care here.
Unfortunately, an anatomic leg length discrepancy can not be corrected with chiropractic care alone. Although adjustments can help properly align the pelvis, correcting a functional leg length if you have both types of discrepancies, it can not make one leg grow longer. In this case, a heel lift is recommended. A heel lift is a small insert that goes inside your shoe, usually under the insole, that helps raise the short leg up, correcting a leg length difference.
If the anatomic difference is 7 mm or less, a heel lift can correct the difference. However, more than a 7 mm heel lift can lead to ankle and Achilles tendon issues over time. For this reason, if you have an anatomic difference of more than 7 mm, the outside of your shoe will likely need to be built up. Don’t worry, a skilled cobbler can usually accomplish this without anyone even noticing.