Hip Impingement Does Not Produce Neurovascular Symptoms During Straight Leg Raise Testing
The straight leg raise (SLR) test should not elicit neurovascular symptoms in patients with hip impingement, as this test is specifically designed to assess nerve root tension from lumbar radiculopathy, not hip joint pathology. If neurovascular symptoms appear during SLR testing in a patient with suspected hip impingement, this indicates coexisting lumbar spine pathology requiring separate evaluation.
Understanding the Straight Leg Raise Test
The SLR test is a procedure where the hip is flexed with the knee extended to passively stretch the sciatic nerve and elicit symptoms suggesting nerve root tension 1. A positive test is defined as reproduction of the patient's sciatica (pain radiating down the leg below the knee in the sciatic nerve distribution) when the leg is raised between 30 and 70 degrees 1.
What the SLR Test Actually Assesses
- The test has 91% sensitivity but only 26% specificity for diagnosing lumbar disc herniation causing nerve root compression 1, 2, 3.
- It evaluates for radiculopathy—dysfunction of a nerve root associated with pain, sensory impairment, weakness, or diminished deep tendon reflexes in a nerve root distribution 1.
- The sciatic nerve or its branches cross both the hip and knee joints, and the test places traction on these nerve roots 1, 4.
Hip Impingement vs. Lumbar Radiculopathy: Critical Distinction
Expected Findings in Hip Impingement
Hip impingement (femoroacetabular impingement) produces mechanical hip joint pain, not neurovascular symptoms 5. The appropriate tests for hip impingement include:
- Impingement sign test (hip flexion, adduction, and internal rotation) 5
- IROP test (Internal Rotation Over Pressure) 5
- FABER test (Flexion-Abduction-External Rotation) 5
- Resisted Straight Leg Raise (RSRL/Stinchfield) test 5
These tests provoke mechanical hip pain, not radicular symptoms 5.
Expected Findings in Lumbar Radiculopathy
When the SLR test is positive for nerve root pathology, the following neurovascular symptoms may occur 1, 2:
- Sciatica: Pain radiating down the leg below the knee in the sciatic nerve distribution 1
- Sensory impairment: Dermatomal sensory changes corresponding to specific nerve roots 1, 2
- Motor weakness:
Clinical Algorithm for Interpretation
If SLR Test is Negative in Hip Impingement Patient
- This is the expected finding 5
- Proceed with hip-specific examination tests 5
- No neurovascular symptoms should be present 5
If SLR Test is Positive in Hip Impingement Patient
This indicates coexisting lumbar spine pathology requiring separate workup 1, 2:
- Perform comprehensive neurological examination including knee strength/reflexes (L4), great toe/foot dorsiflexion strength (L5), and foot plantarflexion/ankle reflexes (S1) 1, 2
- Assess for crossed SLR test (88% specificity for herniated disc) 1, 2
- Evaluate for red flags: History of cancer, unexplained weight loss, fever, intravenous drug use, or recent infection 1
- Consider imaging if severe or progressive neurological deficits are present 2
Common Clinical Pitfall
The critical error is attributing radicular symptoms during SLR testing to hip impingement when they actually indicate lumbar nerve root pathology 1, 2, 5. The SLR test biomechanically loads the sciatic nerve through hip flexion and places the nerve under tension 6. Hip impingement is a mechanical joint problem that does not involve nerve root compression 5.
Perioperative Considerations
During positioning for hip surgery, stretching the hamstring muscle group beyond the normal comfortable range may increase risk of sciatic neuropathy 1. However, this represents a positioning injury risk, not a diagnostic finding related to hip impingement itself 1.