Degenerative disk disease is a general classification including herniated or ruptured disk, prolapsed intervertebral disk, and others.
The disks in the spine are like small sponges that rest between each vertebrae and act as shock absorbers. When arthritis compresses a disk, it tends to bulge out of its alignment; sometimes, it will rupture. When it does, the rupture will usually occur posteriorly. The displaced disk segment may then press on the spinal nerve as it emerges from the spinal cord, or on the cord itself.
A ruptured disk often results in a pinched nerve because of the pressure it puts on nerve tissue. The symptoms that result from a pinched nerve vary according to the location and severity of the injury: a jerking knee, a weak fist, or a numb foot can all be signs of a pinched nerve, and thus, degenerative disk disease.
Diagnosis can be made with simple X-rays. However, if nerve damage is a concern, the doctor may perform an MRI to assess the extent of the damage. Another test to detect a ruptured disk in the lower back is the straight-leg-raise test. The doctor lifts the patient’s heel with his or her leg passively extended. This stretches the sciatic nerve, which is located at the back of the hip and goes down the back of the leg. If it elicits pain, the patient probably may have a ruptured disk.