Testing for the Cause of Back Pain When You Raise Your Leg

If you can't do a leg raise without getting either back pain, sciatica, or a combination of the two, your doctor may suspect a herniated disc is responsible. The straight leg raise test is one common manual test used to determine if a herniated disc or another spine-related malady is at the root of your symptoms.

Purpose of the Straight Leg Test

Sciatica has a number of possible causes, from a tight piriformis muscle to more common causes including herniated disc, spinal stenosis, or spondylolisthesis. For patients dealing with sciatica, the first step is diagnosis.

A manual exam procedure is one in which the testing practitioner uses her hands to position you, move you and/or give pressure against which you resist.

This is a much different approach to determining the source of pain or of a spinal problem than diagnostic imaging tests, which use machines. Generally speaking, both methods are employed during the diagnostic process.

The straight leg raise test is one of the most common manual test procedures performed during a physical exam. Like many of its kind, the goal is to check for nerve movement and sensitivity of nerve tissue to compression.

In fact, there's a name for this type of manual test, which is neurodynamic. Neurodynamic testing includes not only the straight leg raise but others as well.

During the Straight Leg Raise Test

The straight leg raise test seeks to reproduce your pain or other symptoms, so be prepared to experience them for a moment or two while your provider evaluates you. The test is a passive one; you can help her achieve the most accurate result by staying as relaxed as possible and giving an honest summary of what you feel as your leg is lifted.

Procedure:

1. To start, the person examining you will ask you to lie on your back with your legs straight.
2. They will then ask you to turn one of your legs in. It’s important to turn the entire lower extremity. This is so the examiner can accurately correlate the position of your hip and low back with the symptoms you report. The examiner will also ask you to bring your leg in towards the center of your body.
3. Next, the examiner will lift your straight leg up until you complain of pain. If you don’t have pain during the straight leg raise, great. But if the maneuver does cause discomfort, this may be a sign that a herniated disc is responsible for your back or leg symptoms.
4. Depending on the angle of your hip when your symptoms start as you're being tested, your practitioner may determine that something other than a herniated disc is the cause.
5. Both legs are tested in a straight leg raise test, so the steps are repeated with the other leg.

Variations

The examiner may repeat the test with your ankle in a dorsiflexed position, and again with your chin tucked into your chest. (Dorsiflexion is the movement that occurs at your ankle joint when you raise your foot. It is the opposite of pointing your toes.)

These variations may help the examiner check for nerve involvement in specific locations, including the dura mater, or covering, of the spinal cord and/or the spinal cord itself.

A positive sign for nerve involvement from the spinal cord or its covering would present itself as your usual pain in your back or leg, but not in your chin, neck, or foot.

Modifications

If you are unable to lift your leg up while it's straight, or you have difficulty lying on your back, take heart. The straight leg raise test has modifications. This is why it’s vitally important to speak up and let the examiner know your limitations. Another reason to speak up is to avoid an injury during the testing.

Accuracy

Unfortunately, not much research has been done on neurodynamic tests in general.

A 2017 review that looked at the accuracy of neurodynamic tests on predicting radiculopathy, i.e., symptoms that most of us call sciatica, but that are only caused when a spinal nerve root is compressed or irritated in some way. The study found that researchers have yet to reach a consensus as to whether the straight leg raise test is effective for detecting herniated disc and/or spinal nerve root compression.

The straight leg raise test is also widely used to determine how stiff a patient's hamstrings are. But a 2018 study published in the International Journal of Sports Medicine found that hamstring stiffness is not actually an underlying factor in the results of most or all straight leg raise test results.