A crossed straight leg raise test has a specificity of greater than 0.8 for which condition?

• A. Herniated lumbar disc
• B. Spinal stenosis
• C. Sacroiliac joint dysfunction
• D. Lumbar muscle strain

Answer: (A)

The crossed straight leg raise test is a clinical assessment used to evaluate for lumbar disc herniation, specifically the presence of nerve root involvement. When the patient is in a supine position, the clinician raises the unaffected leg while keeping the affected leg relaxed. A positive test occurs if raising the unaffected leg elicits radiating pain down the affected leg, suggesting a significant level of nerve root irritation or herniation.

The specificity of greater than 0.8 indicates that this test is quite accurate in ruling in the diagnosis of a herniated lumbar disc, meaning that when the test is positive, it is highly likely that a herniated disc is present. This high specificity makes the crossed straight leg raise test a valuable tool in distinguishing herniated discs from other conditions such as muscle strains or joint dysfunctions that may not produce the same radiating leg pain with this specific maneuver.

In contrast, conditions like spinal stenosis, sacroiliac joint dysfunction, and lumbar muscle strain may not produce a positive response in the same way this test indicates herniation. Thus, while the test may not be definitive for these other conditions, its high specificity for herniated lumbar discs gives clinicians a reliable indicator in their differential diagnosis.