Did someone inform you that you have an abnormality in the length of your legs? It’s a common occurrence that affects between 40 and 70 percent of the population and is frequently blamed for causing running injuries, so many runners have probably experienced it.
Putting in a heel lift in the shoe with the shorter heel would seem to be a simple solution to the problem of unequal leg length. Is there really something here? Is there any proof that correcting a leg length inequality with a heel lift improves foot function?
If you read the entire post and look at the scientific research on leg length discrepancy, you’ll see that, as usual, things aren’t as cut-and-dry as they might seem. However, American Heelers, an over 100-year-old company that has modified thousands of shoes of variable heights, has given us the much-needed experience to modify your orthopedic shoes to perfection.
Runners’ Leg Length Discrepancy:
Measuring leg length discrepancy
The accuracy of the leg length measurements is the starting point for any discussion of whether or not a given runner has a leg length discrepancy. It looks simple on paper but is incredibly challenging in practice.
Most medical professionals, including physiotherapists, measure patients’ legs using a combination of a measuring tape and the prominences of their pelvis and ankles. The difference can then be calculated by taking the two numbers and subtracting them.
However, studies have repeatedly shown that this is an unreliable and inaccurate method of measurement. A different study showed that 75% of the time, manual measurement methods were off by more than a quarter of an inch.
Medical imaging is the only method of reliably diagnosing leg length discrepancies, especially those of minor severity. CT scans and x-rays have both been proven to be very reliable diagnostic tools.
The primary takeaway from this study is that even a seemingly insignificant difference in leg length when measured by hand cannot be trusted.
Is it possible for the human body to adjust for a leg length inequality?
Suppose your legs are different lengths. From a purely mechanical point of view, it seems obvious that you would be unbalanced, just like a car with one wheel that is much bigger than the others. But because the human body is a flexible machine, it can adapt to changes in running terrain, shoes, and even muscle strength.
There have been a number of studies looking at how well the human body can adjust to an imbalance in leg length.
It should come as no surprise that there are some discernible asymmetries in walking and running gait in people who have either a genuine or artificial leg length discrepancy. However, it is worth noting that these differences in leg length have been corrected using a heel lift, which provides a consistent benefit.
In an older study of walking gait, it was found that impact forces actually increased after the people, who had leg length discrepancies ranging from about 5-20mm, were given a heel lift to correct their discrepancy. This increase in impact forces will last for about a week, after which the body will adjust to having better balance, and the person will have an easier time walking or running.
Differences in leg length and running injuries:
Leg length discrepancies have, however, been linked to a few injuries—possibly due to the asymmetries in gait that they cause. The relationship between leg length inequality and low back pain has been extensively studied due to the widespread belief that bending the spine to account for a shorter limb is one of the body’s compensatory mechanisms.
Over a dozen studies have been conducted on the topic of low back pain and leg length discrepancies, and they have all reached different conclusions: some have found an increased prevalence of leg length discrepancies in people with low back pain, while others, including a well-designed prospective study of 257 college athletes, have found no connection at all.
However, leg length inequality is more reliably associated with hip pain.
A study conducted by one doctor revealed that there was a correlation between leg length inequality and hip pain, with 230 of 274 patients experiencing hip pain on the side of their longer leg.
The correlation between uneven leg lengths and stress fractures is strong. According to the findings of some studies, women who have stress fractures are more likely to have a difference in the length of their legs than other women who do not have these fractures. It is interesting to note, however, that the length of the leg that had the stress fracture did not correlate in any way with the location of the fracture. Different studies have found a connection between differences in leg length and stress fractures in military recruits.
Final Thoughts on Leg Length Disparity in Runners:
Overall, we think that leg length differences are overdiagnosed and overcorrected. Very few doctors or physical therapists use x-rays or CT scans to measure leg length differences, which probably leads to people getting incorrect heel lifts and blaming them for not working.
If your doctor or physical therapist suspects you have a leg length discrepancy, ask if an imaging study will confirm it. Burke Gurney’s review suggests that 20mm (just over 3/4 of an inch) is a good approximate breaking point for those who would benefit from a heel lift.
Furthermore, as with any orthotic intervention, runners will react differently to a heel lift. There is no foolproof way to tell whether a heel lift will make you more stable at the moment, but it is the most widely accepted non-invasive method for correcting leg length discrepancies.
 However, keep in mind the two conditions (hip pain and stress fractures) that have been consistently linked to leg length differences. For the time being, your best bet is to confirm that your leg length discrepancy is real, and if it is, try out our custom heel lift modification service, which most likely will solve your problems. Give us a call at 216-378-2686 or send an email to info@americanheeler.com for more information.