Known also as the Lasegue’s Sign, the straight leg test stretches the sciatic nerve to look for the source of your pain. If you experience pain going down the back of the leg to below the level of the knee when the leg is raised, this could indicate that one or more of the nerve roots that lead to the sciatic nerve is compressed or irritated.
What to Expect
Before performing the straight leg test to determine if you may have sciatica, your physician should ask you about when the pain began. Questions from your physician will include the following:
- How would you describe the pain (e.g. burning, sharp, dull, throbbing, aching, stabbing)?
- How long have you had the pain?
- Were there any inciting injuries or events?
- Has the pain been getting better, worse, or staying the same?
- Do you have any associated numbness, tingling, or weakness?
- Do you have any associated urinary retention (inability to fully empty your bladder) or bowel incontinence?
- Have you had any recent fevers, chills, night sweats, or unexplained/unexpected weight loss?
- Is there anything that makes it better or worse?
How is the Straight Leg Test Performed?
The straight leg raise test can be performed while you are seated or laying down on your back. Your physician will check first check the range of motion on your non-painful side. Then, your physician will flex your hip with your knee straightened. Your physician may have you extend your foot (dorsiflexion) and flex your neck forward. These movements apply stretch to your lumbar nerve roots. If you experience pain while your knee is flexed between 30 and 70 degrees, this is considered a positive test result.
Next, your physician will slowly raise the leg on the side where your pain is until you inform him or her of pain in your back. Your physician might ask you to dorsiflex your ankle and flex your neck along with lifting your leg. This stretches the nerve root. If the added neck flexion affects your pain—either making it worse or causing it to go away—then this is a clear sign. It is important that you do not raise your pelvis from the exam table while doing the movements.
Doctors can also perform this test on patients in a seated position by stretching the sciatic nerve through knee extension.
How to Interpret the Straight Leg Raise Test?
A positive result happens when pain radiates down the leg to at least below the knee when your afflicted leg is raised between 30 degrees to 70 degrees. Many times, patients feel pain all the way down to the big toe. The sensitivity might improve when you extend your foot upward between 10 and 30 degrees toward your shin. This movement uses muscles in the front part of your lower leg. Relevant history and decreased range of motion are also taken into consideration.
A negative straight leg raise test (i.e., no pain radiating down the leg with the test maneuver), may indicate that your pain is not due to a significant herniation, however it is only one of several potentially useful pieces of information Depending on the results of your physical exam, your physician may feel the need to order more diagnostic tests.
A negative or non-positive test result is when the lower back is the only place you experience pain and you do not have the radiated pain below the knee. Some physicians may order more tests based on your straight leg test.
The straight leg test is a simple way to determine if sciatica is the source of your pain in your buttocks, lower back, and leg. Your doctor may recommend other diagnostic tests to pinpoint your pain and determine if it is sciatica. If your doctor diagnoses you with sciatica, pain is typically managed with relative rest. While complete bed rest is not recommended, you may be advised to modify activity to avoid or limit aggravating activities. Most people with sciatica don't require surgery and 70-80 percent of patients improve within a 4 to 6 weeks.