 Most disc herniations occur when a person is in their thirties or forties when the "nucleus pulposus" is still a gelatin-like substance.With age the "nucleus pulposus" changes ("dries out") and the risk of herniation is greatly reduced.After age 50 or 60, osteoarthritic degeneration (spondylosis) or spinal stenosis are more likely causes of low back pain or leg pain.