disc disease (DDD) is characterized by biochemical and structural changes of
the intervertebral disc which lead to altered appearance and physical
properties of the disc. The cause is multifactorial and is associated with
aging. A degenerative disc may be asymptomatic or may be associated with local
neck or back pain and in some cases extremity pain due to radiculopathy. The
loss of disc volume and vertebral disc height may be associated with secondary
complications such as a spinal joint pain syndrome and nerve encroachment. A
degenerative disc becomes more vulnerable to disc fiber disruption (annular
tears) which can lead to disc herniation.
When discs degenerate, they flatten out much like a cushion
flattens out over time. Magnetic
resonance scans (MRI) of degenerated discs show a loss of water content in the stuffing
(disc material/nucleus pulposus). If the wall of the cushion, the annulus,
degenerates, it weakness and bulges and is called a bulging disc. If the stuffing of the cushion (disc)
begins to come out of the cushion all the way through the outermost layer of
the cushion (annulus) it is called a herniated disc.
characteristic features of disc degeneration include disc dehydration
(dessication), fibrosis, narrowing of the disc space, diffuse bulging of the
disc and the development of annular tears. It also includes the development of
bone spurs (osteophytes along the boney margin of the disc and thickening
(sclerosis) of the vertebral endplates. Degeneration weakens the intervertebral
disc and renders it more vulnerable to compromise with normal stress and strain
and to injury. The term spondylosis deformans may be used to describe
age-related disc changes. The term intervertebral osteochondrosis may be used
to describe disc degeneration secondary to a pathologic (disease) process.
Disc degeneration occurs with equal prevalence in males and
females. The back pain associated with degenerative disc disease (DDD) occurs
most frequently between the ages of 45 and 65. Most individuals over 40 years
of age are found to have one or more degenerative discs. They are most often
detected in the low back (lumbar spine).