As a child, Denise Marandola of Wilmington, Del., could pinpoint the pain to her midback, on the right half, at the tips of her ribs. When she bent over, the bulge on that right side rose higher than on the left. Marandola was 12 when she learned she had scoliosis.

Not everyone experiences pain. Most people who have scoliosis, an abnormal curvature of the spine, don't. At its worst, scoliosis can interfere with the function of organs, diagnosed when children are entering puberty, most often in females. Three-to-five out of every 1,000 children develop scoliosis. Rarely does it begin to occur in adults.

While thought to be hereditary, the cause of most cases of scoliosis is unknown, says Dr. Peter Gabos, co-director of Alfred I. duPont Hospital for Children's Center for Spine and Scoliosis Surgery in Wilmington.

Scoliosis affects girls twice as often as boys, while the ratio of severe curves from scoliosis in girls to boys is about 7 to 1, Gabos says.

"Typically, a sixth-grade girl will have very long legs and a very short trunk," Gabos says. "After that, they basically grow into their trunk, and during that very rapid phase of spine growth, the spine grows basically to meet the (growth) of the lower half of the body."

Surgery is typically performed on children with a spine curvature that exceeds 50 degrees. The main goal is to stop the curve from increasing. A secondary goal, Gabos says, is to rebalance the spine toward a more common contour.

"We're taking a lot of little, crooked bones and turning them into one straight solid bone," he says. "We don't treat the entire spine, only the part that's curved. The part above the curve and below the curve is left untouched."