This term is used to describe pain radiating from the back down one leg caused by pressure on a nerve. The pain usually goes down to the foot but might only radiate to the knee. It is usually caused by a slipped disc in the lower back. The extend to which it travels down the leg depends on the nerve root involved. Most lumbar disc protrusions occur in the lower lumbar spine which causes the pain to go down to the foot. In the case of higher lumbar disc protrusions it may only involve the thigh.

There are, of course other causes for leg pain. So-called ‘referred pain’ often originates from the small joints in the back of the spine (facet joints – see ‘The normal structure of the spine’). This pain is felt in the buttock area and back of the thigh.

For further information see ´lumbar disc protrusion’.