Leg Length Difference – What is a Leg Length Discrepancy?

Leg Length Differences

Seeing movement therapy clients is a source of fascination for me. For one thing, I get to observe the attitudes people harbor in relationship to their condition. And how vastly different these attitudes can be between people – for the very same body problem.

Let’s take leg length difference as an example. A leg length difference, called leg length discrepancy in the clinical realm, occurs when one leg is shorter than the other. Uneven leg length problems come in two types.

First there’s the type you can often do something about. This type of leg length difference is due to your body’s adaptation to some change in alignment. The change in alignment is often introduced by a shift in positioning (to help you balance or stay out of back pain, for example) or a condition like scoliosis.

Generally the alignment change begins as a compensation for a lack of support or balance somewhere in your body. In other words, the functional leg length discrepancy (aka functional shortening) as it’s called is due not to your biomechanical structure, but to something you did along the way. Your legs really are the same lengths, but your structure took a shift in alignment and made it (and/or its repercussions) a part of your posture. For example, sometimes scoliosis creates or contributes to a leg length difference. Because the spine curves to the side (abnormally) in a scoliosis, the muscles on the convex side tighten, which causes the pelvis on that side to lift up. The leg on that hip also rises and result is that it can look like one leg is shorter than the other.

Note: this has nothing to do with guilt! It’s about musculoskeletal adaptation, a natural process for all of us.

So, if you have a functional leg length difference, you’ll probably have one hip hiked up higher than the other.

What specifically might create a functional leg length difference in your body? Contracture is a big one. Contracture may be present in the spine, legs or butt. Taking the hip hiking example further, if your inner thigh muscles (adductors) are tight, it will tend to bring the pelvis on that side closer to the leg, lifting the hip –and leg- on that side. Especially if you happen to be standing on that leg.

If your muscles are weak, and/or you are obese, it may be more difficult to accurately measure and determine a leg length difference. But physical therapists and orthopedic doctors have their ways, and are usually able to accurately determine if you have a leg length discrepancy.

The other type of leg length discrepancy is the true leg length discrepancy. This one is actual – your thigh or leg bones are not the same length. It’s due to a congenital problem. In other words you were born with it.

The American Academy of Orthopedic Surgeons says that once the leg length difference is 1.66” or 3.5-4% of your other leg, you may start getting problems walking, etc. They also note that while some people think their back pain and/or susceptibility to back injury is due to a leg length discrepancy, study results are mixed. What this means is they really can’t say definitively if a leg length difference causes a bad back or not.

So what’s so fascinating about all this?

Some people don’t take the time to understand the distinction between the types of leg length differences, and therefore are unclear about what’s causing theirs. These people just want a fix. Is that how you are?

My circle of acquaintances generally does not include the type of people who automatically elect surgery, although I know they’re out there. The American Academy of Orthopedic Surgeons backs me up on this. They say the risks of surgery outweigh the possible benefits.

Another possible cure is either a shoe lift or custom orthotics. My observations fall into 2 categories:

• Orthotics for Leg Length Difference
• Leg Length Discrepancy Common Sense

Some people with extreme attitudes on the other side of the question from those who prefer surgery are convinced that they can move and exercise their leg length difference away. I believe they are correct, as long as their leg length difference is the functional type. These die hards won’t consider an orthotic or shoe lift no matter how uncomfortable they are without them. To them I say – be sure you understand exactly how your leg length discrepancy is created in your body. We all have different configurations, and by knowing which muscles are tight and which are weak, you’ll better be able to determine how to go about releasing yourself from your leg length difference.

Also, the body learns by doing and feeling. You might want to reconsider your adamant resistance to a shoe lift or custom orthotic – it isn’t the worst idea in the world. A shoe lift or custom orthotic may help your body experience and adapt to the more balanced aligned configuration, and make it easier for you to completely stretch and strengthen out of your leg length difference.

For those who want the quick fix, beware of the surgery. Remember, even the orthopedic doctors say the surgery is risky, and to operate is their business.

Wearing a custom orthotic or shoe lift may be an effective quick fix. I’ve had experience with Foot Levelers and I liked them a lot. Again, you really need to know how your leg length difference is created in your body to effectively determine if, for example, a shoe lift is the most appropriate aid, or if you need custom orthotics. It will also help you pick out the best shoe lift for you, if that’s what you decide to do.

Source:
Kinser, C., Colby, LA, Therapeutic Exercise: Foundations and Techniques. 4th ed. F.A. Davis Company. Philadelphia. 2002.

Magee, D.J. Orthopedic Physical Assessment. 4th ed. Elsevier Sciences. 2006. St. Louis MO.

Vaccaro, A. Spine: Core Knowledge in Orthopaedics. Elsevier Mosby.2005. Philadelphia PA.

Limb Length Discrepancy. Your Orthopedic Connection. AAOS website. Last Reviewed and Updated: July 2007. Accessed: June 29, 2010.