Which physical finding indicates a high probability of a herniated lumbar disc?

A positive crossed straight-leg raise is a significant indicator of a herniated lumbar disc, as it suggests nerve root irritation or compression on the opposite side of the straight leg being raised. This test is particularly indicative of a lumbar disc herniation that is affecting the lumbar nerve roots (usually L4-L5 or L5-S1), making it an important finding when evaluating back pain.

Decreased thoracolumbar range of motion further supports the diagnosis, as patients with a herniated disc often exhibit limitations in movement due to pain and muscle guarding. Additionally, a positive straight-leg raise at 30° indicates a high level of sensitivity for lumbar disc herniation as it demonstrates that even a slight elevation of the leg exacerbates symptoms, correlating strongly with nerve root involvement.

The combination of these physical findings provides a robust clinical picture supporting the likelihood of a herniated lumbar disc in the patient being assessed.