I've been reading up on surgical fusion procedures for scoliosis. Our niece is going to have one of these operations. I see there's some concern about over correcting the curve. How do they avoid this problem?

Surgeons evaluate each case very carefully in order to avoid overcorrection or undercorrection. They use the results of the clinical exam and X-rays to carefully plan each step of the procedure.

For example, angles, flexibility, and magnitude are calculated for each curve. In your niece's case, it sounds like there may be more than one curve. This is fairly common. When one curve progresses far enough, a second spinal curve will develop. The body tries to keep the head and sacrum in the middle. This means the spine makes the necessary adjustments to accomplish that goal.

Undercorrecting the spine can lead to chronic deformity. The surgeon isn't always able to get 100 per cent correction. Overcorrecting may off-balance the head and spine's position over the sacrum. Experience helps guide the surgeon in avoiding either of these errors. X-rays are used throughout the procedure to check and double check spine position, angles, and correction.