A positive straight leg raise test in acute lower back pain suggests what condition?

A positive straight leg raise test is indicative of nerve root irritation, particularly when assessing for potential conditions affecting the lumbar spine. In the context of acute lower back pain, this test is most closely associated with a herniated disc. When the leg is raised straight, it creates tension in the sciatic nerve and can elicit pain if there is a herniated disc compressing or irritating the nerve root as it exits the spine.

This specific test helps differentiate the source of the pain. A patient experiencing pain below the knee, often described as radiating along the leg, typically points toward a herniated disc due to radiculopathy caused by a bulging or protruding intervertebral disc. The postural position during this assessment can aggravate the symptoms, confirming the suspicion of disc-related issues.

Muscle strain, sciatica, and spinal stenosis can also cause lower back pain, but these conditions would yield different clinical findings or pain patterns during the straight leg raise test. Thus, the positive result of this test strongly suggests a herniated disc as the underlying cause of the acute lower back pain.