Degenerative Disc Disorder

Anatomy

The bones of the spine, called vertebrae, are separated from one another by discs.  The discs serve as shock absorbers and serve to accommodate motion in the spine.  Spinal motion occurs in segments that include the disc, the vertebral bodies adjacent to the disc, spinal ligaments, facet joints and deep stabilizing muscles of the spine.

The Problem

Degenerative disc disorder involves weakening of one or more discs and can develop due to injury or to aging.  Age related changes begin to be seen in the discs in one’s 20s or 30s.  Recall that the soft, jelly-like core of the disc (nucleus) is mainly composed of water.  With aging, water content is lost and the disc becomes thinner and more stiff.  This changes the structural relationship between the nucleus and the firm outer rim of the disc (annulus).

Small tears appear in the annulus and can result in back pain.  These tears heal and scar over.  If repeated injuries to the low back occur, the process of repeated tearing and scar formation progressively weakens the outer disc wall and increases the risk of disc herniation.

Thinning and stiffness in the discs also allows neighboring vertebrae to draw closer together and can lead to loosening of spinal ligaments and local instability.  This process changes the loading forces across the facet joints and can cause facet joint injury.  Pain from these joints can generate signals to the spinal cord that can lead to weakness and atrophy of deep stabilizing muscles of the spine.

Spurs can form along the edges of the vertebrae and along the facet joints.  These bone spurs may lead to narrowing of the central canal of the spine and nerve root canals, known as spinal stenosis.

Diagnosis

Diagnosis begins with a thorough history and physical examination.  X-rays of the low back can indicate the presence of decreased disc space height and can provide a general indication of bone spur formation, but more advanced imaging, such as an MRI, is required to visualize the full extent of degenerative changes involving the disc, vertebral bodies, spinal ligaments and facet joints.

Treatment

Treatment begins with methods to decrease pain and inflammation.  This may include ice, heat, pain medications or anti-inflammatories.  Additional treatment strategies depend on whether the degenerative disc changes have led to secondary problems, such as disc herniation, facet arthritis or spinal stenosis.  Please refer to those sections for general treatment strategies.

Once acute pain has been treated, it is important to direct attention to reconditioning and strengthening the stabilizing core muscles to restore more normal function to the back and to decrease the frequency and severity of future pain flares.