Disc Center Weakens: Over time, the nucleus (or center) of the disc becomes damaged and loses some of its water content. This center is called the pulposus, and its water content is needed to keep the disc functioning as a shock absorber for the spine.
Nucleus Collapses: Unable to act as a cushion, the nucleus collapses. The vertebrae above and below this damaged disc slide closer together. This improper alignment causes the facet joints – the areas where the vertebral bones touch – to twist into an unnatural position.
Bone Spurs Form In time, this awkward positioning of the vertebrae may create bone spurs. If these spurs grow into the spinal canal, they may pinch the spinal cord and nerves (a condition called spinal stenosis). The site of the injury may be painful.
Symptoms Some people experience pain, numbness or tingling in the legs. Strong pain tends to come and go. Bending, twisting and sitting may make the pain worse. Lying down relieves pressure on the spine.