I have a problem with slipping vertebrae and slipping discs. After two operations to fuse two separate levels, I still have low back pain. The doctor says my low back is “too flat.” Why does this make a difference?

There are three main curves in the spine. One is along the back of the neck. It dips inward and is called a cervical lordosis. The second is the upper-to-mid back, which is more of a hump-curve. This is called kyphosis. The third is the lumbar lordosis of the low back. Some people call this a “swayback.”

The low back becomes flat if there’s not enough curve or lordosis. The lordotic curve places each bone at just the right angle to keep the disc spaces open. It also maintains the right amount of tension on the ligaments, joints, and muscles.

Kyphosis of the lumbar spine causes an increase in the amount of pulling load on the posterior soft tissues. The muscles respond by tightening up or increasing their tone. The constant tension of the protective muscles can cause even more low back pain called tonicity lumbago.