How a Normal Lumbar Lordosis Angle Is Determined

Woman's back

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Lumbar lordosis—the forward low back curve as seen on a profile view of the human body—is a key element of posture, whether good or bad.

Most people have at least a vague awareness that a small amount of curve in their low back is normal. But when it comes to a standard measurement that everyone can relate to, spine doctors and researchers do not agree on exactly what "normal" is. Nor are they clear on how to accurately test for it.

That said, the range, according to the website Physiopedia, is between 39 and 53 degrees, but, they add, lumbar lordosis angles vary wildly between people.

What This Means for You

The first step to measuring the angle of your low back curve is to get an X-ray. But even this can be problematic. A 2014 study published in Spine journal found that positioning during testing as well as the number of spinal bones included in the measurement may contribute to skewed results.

Adding to the confusion are characteristics you bring to the X-ray table. According to the study authors anything from age, gender, ethnicity, engagement in sports and physical activity and how strong and flexible your muscles are can make it difficult, if not impossible, to determine and measure a normal lumbar angle.

Another characteristic that confuses the issue is your body mass index, which is a height to weight ratio used to determine if you are underweight, average weight, overweight or obese.

Interpreting the X-Ray

If you are a math geek, you may be wondering which method or methods are used for interpreting an X-ray in an effort to determine the exact degree of lumbar lordosis. It turns out that a number of systems may be helpful, including:

  1. Determining the lumbar curve's Cobb angle from an X-ray taken in profile.
  2. Using centroid, tangential radiologic assessment of lumbar lordosis method (TRALL)
  3. Using the Harrison posterior tangent line-drawing methods

A 2001 study found that determining the Cobb angle is usually the most accurate for the low back. 

What's the Benefit of Coming Up With a Normal Value?

If coming up with normal values for a very normal phenomenon such as the lumbar curve is so hard, why do it at all?

Basically, it's useful information. Spine surgeons use the lumbar lordosis angle when making decisions about where and how to operate. Researchers from the 2014 studies mentioned above found an association between the lumbar lordosis angle and spine conditions such as spondylolysis and isthmic spondylolisthesis.

Similar to the case of spine surgery and lumbar lordosis mentioned above, knowing the exact amount of lumbar lordosis may possibly inform treatment choices for these two back conditions.

And a 2017 systematic review and meta-analysis identified a strong relationship between low back pain and the loss of the lumbar lordosis angle, especially when the decreased lumbar angle was associated with disc degeneration or herniation.

A Word From Verywell

For those of us who wish to be pro-active about addressing our posture issues, this lack of decisiveness about "normal" for the all-important low back curve can be frustrating. To that end, here are a few things to keep in mind.

In and of itself, a lumbar lordosis does not present a problem But once it becomes excessive, it can tighten back muscles and cause pain. And it may increase your risk for facet joint pain or spinal arthritis.

Conversely, if your lumbar lordosis decreases, perhaps because you have a habit of sitting with a slouch every day at work, you may increase your risk for a disc injury.

While it is possible to be born with an excessive or minimal lumbar curve, this is rare.

Most of the time, posture habits and conditioning is at the root of a lumbar curve angle that is out of the normal range.

Based on this, likely the best way to get your low back curve in line is with a core exercise program. Strengthening your core may be just what you need to keep your low back posture in the normal range, even though the exact numbers may not be available to you.

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