It was most common at the L5/S1 level, and, of the abnormal group, 36% (n = 11) showed the most degenerative change. Disc height reduction was also found to be most common at the L5/S1 level. However, ...

a progressive and irreversible condition that leads to a loss of disc height that can compress the spinal nerves and cause excruciating, intractable pain with devastating social consequences.