Straight Leg Test to Check for Strength and Stability

The straight leg raise test is done to gauge several aspects of your legs' strength and stability. It's most often performed to check nerve and muscle function, and it may reveal why you're unable to raise your leg.

This article takes you through what a straight leg raise test is, why it is performed, and common conditions diagnosed using it.

What Is a Straight Leg Test?

The straight leg raise test is a commonly performed diagnostic maneuver used as part of a physical exam. It provides important information about lower body functionality and helps guide referral and therapeutic decision-making.

The test is typically performed while you lie flat on an exam table or bed. Either you or your healthcare provider then raises your leg, possibly with light resistance, to assess the leg's strength and performance capability.

Who Should Have a Straight Leg Test?

A straight leg raise test can help diagnose multiple conditions, like lumbar disc issues, nerve root irritation, and muscle tightness or injury. It is typically used when people present with low back pain and nerve pain that radiates down the leg.

Performing this maneuver helps to determine whether imaging may be necessary (e.g., X-rays, MRI) and any potential need for a specialist. 

Testing Nerve Irritation

The straight leg test can be altered to test sciatic nerve function rather than muscle and tendon function. The sciatic nerve exits from the lumbar spine (lower back), and then passes behind the hip and down the back of your leg.

Conditions that cause sciatic nerve irritation include:

• Spinal stenosis
• Disc herniations
• Sciatica

Rather than having you attempt the leg raise, the examiner lifts your heel with the knee in a straight position. When it's as high as possible, the examiner points your toes toward your head. 

This stretches the nerve and can recreate symptoms of nerve pain going down the leg. This type of test is called a tension sign and can be very helpful in determining the best treatment for a nerve condition. 

Testing the Extensor Mechanism

The straight leg raise test can be used to assess the function of the quadriceps muscle and its attachment to the shin bone.

An inability to perform a straight leg raise can be caused by disruption of the following:

• Quadriceps tendon
• Patella (knee cap)
• Patellar tendon

If you have a condition such as a torn quadriceps tendon or a patella fracture, you'll likely be unable to perform this maneuver. 

Because of the disruption of the extensor mechanism, despite your effort to lift the leg, there is nothing to pull against, and therefore you can't perform this function. A straight leg raise test is the key diagnostic test to assess for these conditions.

Summary

The straight leg raise test is a maneuverability test that gauges strength and stability. If you are unable to raise your leg, this test may be a key factor in your diagnosis. It is relatively simple to perform and helps determine the need for further testing or possible referral to a specialist.