What it is
Intervertebral discs are composed of a tough outer ring (annulus fibrosus) and a gel-like center (nucleus pulposus). With age, the disc gradually loses water content, height, and flexibility — a process called degeneration. The term "degenerative disc disease" is somewhat misleading; it describes a normal aging process that happens to become painful in some people and not others.
On MRI, disc degeneration appears as darkened discs (reduced T2 signal) and reduced disc height. These findings are common: by age 50, most adults have at least some degenerative changes on imaging. The presence of these changes on an MRI does not by itself explain someone's pain — correlation requires careful clinical evaluation.
When surgery is considered
Surgery for axial (back pain only) degenerative disc disease is genuinely controversial. Spinal fusion can reduce pain in carefully selected patients, but patient selection is critical, outcomes are variable, and surgery is not appropriate for most people with this diagnosis.
Surgery is more appropriate when degenerative disc disease has contributed to adjacent instability, significant spondylolisthesis, or refractory stenosis, and less appropriate as a treatment for back pain alone. An honest conversation about realistic expectations — and the evidence — is a necessary part of any surgical discussion.