leg-length inequality

What causes leg-length inequality or leg-length discrepancy?

At C1 we’ve been having a run on patients presenting with “hip pain”.  This turns out to be classic leg-length inequality (LLI) or leg-length discrepancy rather than true hip joint pain.

Leg-length inequality is surprisingly common.  There’s a staggering 90% of us having some form of inequality.  23% of the general population have a discrepancy of over 1 cm – which is a fair discrepancy.  Treatment for LLI include getting back leg-length equality in order to get a level pelvis and improving function.

Guidelines set out by James J. McCarthy, MD, and G. Dean MacEwen, MD for treatment of leg-length inequality are as follows:

  • <2 cm — no treatment or a lift in the shoe (so nearly every case, ever);
  • 2 to 6 cm — an epiphysiodesis or shortening procedure is considered;
  • 6 to 15 cm — a lengthening procedure is considered but this is so rare as to be unique.  A leg length inequality of 15 to 20 cm — may require a staged lengthening, lengthening combined with epiphysiodesis, or even amputation!  There are numerous complications with limb lengthening procedures.  This is because they are so complex, and they occur frequently, even in experienced hands.

What causes LLI?  

Well, it is uncommon for your limbs just to grow to different lengths, so an anatomical LLI is usually caused by:

  1. Trauma – breaking a leg or ankle being the most likely cause.
  2. If this hasn’t happened that we’d look at the arch of the foot and see if they are symmetrical as a collapsed arch can lower a hip height.
  3. However, the most common cause of LLI we have seen at the clinic is caused by pelvic rotation at the sacroiliac joint.  This is usually treatable depending just on how much movement you can back into the joint and they have a tendency to resolve well if they can be moved.

I’d also resist a heel lift as they are a real pain.  They have to be moved between shoes and, on philosophical grounds, they also only treat a sign and not a cause in many cases.

We’ll talk more about this as it is an important and massively overlooked subject.  Here’s a later blog on the impact of LLI in athletes

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