Lumbosacral Angle Overview

The lumbosacral angle describes the degree between the lumbar and sacral portions of the spine. It can have an impact on back pain and on the risk of a slipped disc in the lower back.

Quick Spinal Anatomy Review

The entirety of the spine from the neck down through L5, the lowest lumbar vertebra, rests on the top of the sacrum. This bottom joint, L5 - S1, is also known as the lumbosacral joint.

The sacrum is a triangular bone that is wedged in between the back of the two hip bones. It helps stabilize the spinal column and eases the load on your spine by distributing the weight of your body throughout the pelvis and down into the lower extremity.

The spine has four main curves, categorized by regions:

• Cervical, at the neck
• Thoracic, which is the upper and mid-back area
• Lumbar, which is your low back
• Sacral curve, located at the base of your spine

The directions of these curves alternate—one right after another. This helps provide both support and balance to your body in many different positions. Common movements such as sitting, standing, walking, bending reaching, twisting, and lifting are stabilized and made easier by the alternating directions of the spinal curves.

The Lumbosacral Angle Defined

Your whole spine sits on top of the lowest sacrum bone. The top of the sacrum bone is called the sacral base and it is not horizontal—rather, it tilts at an angle. The degree of sacral base tilt varies between individuals and can range between steep and flat.  

As the base of support for the spine, this sacral angle determines, at least in part, the degree of curve in the lumbar, thoracic and cervical areas. Starting at the foundation at the top of the sacrum and going up the spine, one angle influences another. 

The Lumbosacral Angle and Spondylolisthesis

One common spinal problem, spondylolisthesis, can affect the spine at any level. It is one of the common problems at the L5-sacrum joint. Spondylolisthesis is forward slippage of the top bone, the L5, relative to the bottom bone, the sacrum. 

This condition can occur at any age, but the cause at each age differs.

• In children and adolescents, it tends to start as injury, like a hairline fracture, to a small area at the back of the spinal vertebral bone known as the pars interarticularis. Young athletes are most at risk, especially when their sports require repetitive forward and back spinal movements. Over time, the pars injury can develop into spondylolysis and finally spondylolisthesis.
• In older people, spondylolysis and spondylolisthesis tend to be caused by degenerative changes in the spine. 

These changes and injuries can affect anyone, and the lumbosacral angle may have some effect on the risk. A study published in 2020 showed that a steeper tilt of the lumbosacral angle was associated with a higher risk of disc slippage of the lower spine.

Can Exercise Improve a Lumbosacral Angle?

If you have back pain, you may be wondering if it's possible to correct an excessive lumbosacral angle with exercise.

A 2018 study published in the Journal of Physical Therapy Science looked at the results of a twelve-week lumbar stabilization exercise program.

The researchers found that while the program helped strengthen core muscles, i.e., those muscles most responsible for stabilizing the spinal column, especially in the upright position, it did not actually alter the lumbosacral angle. The study authors surmise that the reduction in pain after the twelve weeks of work was likely due to increased muscle strength and joint flexibility, lessening the load placed on the spine.

For people who have high-grade spondylolisthesis, surgical reduction of the angle may reduce the risk of slippage. But this is major surgery, and the procedure has risks, so it is not typically considered an option in terms of risks and benefits unless there are severe symptoms.

A Word From Verywell

It's unlikely that you would know what the extent of your lumbosacral angle is unless you've already had imaging tests. A good rule of thumb is to take care of your spine by avoiding excessive repetitive motions or poor posture for prolonged periods of time. Exercising regularly can also build muscle strength, which stabilizes your spine so that unexpected movements will be less likely to cause pain or injuries,