Unable to Lift Your Leg without Pain? There's a Test for That.

What is the Straight Leg Test?

A health practitioner administers the straight leg raise test.
A health practitioner administers the straight leg raise test. Eliza Snow/E+/Getty Images

If you can't lift your leg without getting either back pain, sciatica or a combination of the two, your doctor may suspect a herniated disc is responsible. One common manual test used by many health providers to determine if herniated disc (along with other spine related maladies) are at the root of your symptoms is the straight leg test.

In case you were wondering, 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 from diagnostic imaging tests, which use machines. Generally speaking, both methods are employed during the diagnostic process.

The straight leg 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 includes not only the straight leg test but others as well: These are called neurodynamic tests.

A Sciatica and Back Pain Manual Test

For patients trying to get rid of sciatica, the first step is diagnosis. What many people don't know is that sciatica has a number of possible causes, from a tight piriformis muscle (which, actually, is rare) to more common causes including herniated disc, spinal stenosis or spondylolisthesis.

A straight leg test, then, is one of several tools doctors use to determine whether leg symptoms are due to herniated disc, slipped disc, spinal instability, extra tight hip or back muscles, or something else. 

What Happens During a Straight Leg Raise Test

The straight leg test is 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 come up with the most accurate result by staying as relaxed as possible and also reporting honestly what you feel as your leg is lifted.

To start, the person examining you will ask you to lie on your back with your legs straight. She 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.

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 positive sign that a herniated disc is responsible for your back or leg symptoms. Depending on the angle of your hip when your symptoms start, your practitioner may determine that something other than a herniated disc is the cause.

Both legs are tested in a straight leg raise test. 

The examiner may repeat the test with your foot in a dorsiflexed position. (Dorsiflexion is the opposite of pointing your toes,) and again with your chin tucked into your chest.

 These variations may help her check for nerve involvement in specific locations: The dura mater (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.

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

Is the Straight Leg and other Neurodynamic Tests Accurate?

Unfortunately, not much research has been done on neurodynamic tests in general. And according to a 2017 review that looked at the accuracy of neurodynamic tests on predicting radiculopathy (i.e., symptoms that most of us call sciatcia, but that are only caused when a spinal nerve root is compressed or irritated in some way,) researchers have yet to reach a consensus as to whether the straight leg test is  effective for detecting herniated disc and/or spinal nerve root compression.

Source:

Magee, D. Orthopedic Physical Assessment. Enhanced Edition. 4th ed. Elsevier. St. Louis. 1997.

Tawa, N. et. al. Accuracy of clinical neurological examination in diagnosing lumbo-sacral radiculopathy: a systematic literature review. BMC Musculoskelet Disord. Feb. 2017. https://www.ncbi.nlm.nih.gov/pubmed/28231784

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