Degenerative disc disease is a condition that is commonly misunderstood. A degenerated disc is not actually a disease—it is part of the normal aging of the spine. When a spinal disc degenerates, it loses its ability to function efficiently as part of the spinal joint, which in turn can lead to back pain and possibly pain that radiates through the extremities. As a disc degenerates, the soft inner gel in the disc can leak back into the spinal canal. This is known as disc herniation, or herniated disc. Once inside the spinal canal, the herniated disc material then puts pressure on the nerve, causing pain to radiate down the nerve leading to sciatica or leg pain (from a lumbar herniated disc) or arm pain (from a cervical herniated disc).