Degenerative disc disease, as the name explains, is the resulting pain of discs degenerating or deforming in shape over time. There are many reasons for discs to degenerate; injury, infection, smoking, aging being the most common cause found among patients.
A degenerated disc also causes the vertebra bone to significantly grow, also known as a bone spur or osteophytes. This increased bone structure then causes spinal or foraminal stenosis-narrowing causing pain and restricting movement.
Degenerative disc disease is NOT really a disease; it is a misnomer. With several symptoms and severity of the resulting pain, there is no set definition for degenerative disc disease found, and pain management specialists have varying opinions on the matter.