What To Do If You Have a Leg Length Discrepancy

author : AMSSM
comments : 2

My left leg is significantly shorter than my right by 7mm. For the bike I got an extra shim in my cleat, so I'm wondering if orthotics would be called for in my running shoes?

Member Question

Last weekend I had my first bike fit done and in the process learned that my left leg is significantly shorter than my right by 7mm. For the bike I got an extra shim in my cleat, so I'm wondering if orthotics would be called for in my running shoes? Overall, I am a healthy runner, but when something does hurt, it is pretty much always on the left side. I have been dealing with piriformis syndrome in my left leg for well over a year now (PT helped, but didn't totally eliminate it).

That said, are "over the counter" orthotics helpful? Any recommended brands? Or is it safer to go straight to the doctor for custom fit ones?

Answer by Rachel Biber Brewer, MD
Member AMSSM

Leg length discrepancies are actually quite common in the general population. Most people adapt to the difference without any adverse effects, but some runners with a discrepancy experience lower extremity problems such as IT band syndrome, piriformis syndrome, hip pain, or low back pain.  A difference of under a quarter inch is not grossly abnormal and usually does not require intervention.  However, your leg length difference is just above that threshold, and you may benefit from an orthotic or heel lift.

In order to determine if your leg length discrepancy is altering your gait and leading to injury, it is helpful to have a gait/running evaluation.  Gait evaluations can be done by healthcare providers like a physical therapist or your sports medicine physician.  Likely you are experiencing a functional leg length discrepancy (as opposed to congenital or structural), meaning that the difference occurs as a result of muscular weakness or inflexibility at the pelvis or lower leg, or other mechanical issues like flat feet or high arches.  Having someone grossly evaluate your gait assists in targeting such issues.

Since your leg length discrepancy could be contributing to your lower extremity problems as evidenced by your history of left-sided pain, you may benefit from an orthotic.  If you have a neutral gait, you should try a simple heel lift (any brand over the counter) in your left shoe.  If you pronate, using an over the counter insert in both feet (such as Superfeet) would help eliminate the pain.  Custom orthotics are generally not necessary unless you have abnormally high arches.  Again, having someone assess your gait will help you tease out the biomechanical issues in your lower extremities and determine what insert is right for you. 

Also, functional leg length discrepancies respond well to continued physical therapy with a focus on core strength and lower extremity flexibility.  Continue with the exercises you have learned in PT and make them a part of your routine during both your peak training and off-season. 

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date: March 28, 2012

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The American Medical Society for Sports Medicine (AMSSM) was formed in 1991 to fill a void that has existed in sports medicine from its earliest beginnings. The founders most recognized and expert sports medicine specialists realized that while there are several physician organizations which support sports medicine, there has not been a forum specific for primary care non-surgical sports medicine physicians.

FIND A SPORTS MEDICINE DOCTOR

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