The intervertebral disc is a fibrocartilaginous structure found between the bodies of the vertebra. There is a disc between each pair of vertebra in the lumbar spine. Think of this disc as being a jelly doughnut: there are the outer fibrous rings that surround a soft inside. The outer annular rings are thinnest posterior and lateral. Most disc herniations occur here due to the weakness of the disc wall. The disc functions as a cushion, allows for movement, and serves as a cartilaginous joint between adjacent vertebrae. Inflammation, damage or degeneration of a disc can cause a range of symptoms that vary based on the severity of the problem. The lumbar fourth and fifth (L4-L5), and lumbar fifth and sacrum (L5-S1) levels have the highest rate of disc degeneration and herniation.
Disease Degenerative disc disease is not an actual disease but is the term used to describe the progression of changes, gradual wear-and-tear, and dysfunction associated with symptoms secondary to disc degeneration. Degeneration of the disc is normal with aging but can be accelerated in certain situations as a result of trauma, repetitive strain or injury and musculo-skeletal imbalances like scoliosis. Disc degeneration itself is not a problem, but the associated conditions that may develop as it progresses can be symptomatic and debilitating.