There aren't a lot of studies to show how often negative outcomes occur. One study of several hundred children and teenagers reported a 19 percent rate of poor results. Most of these were caused by problems with the hardware used to hold the spine together. Sometimes a hook or screw loosens or just fails to do its job.

There has been some question of whether returning to sports or other physical activities too soon can cause problems. So far, there is no real proof that surgical failure occurs after returning to activities too soon. This is an area of new research, so perhaps more information will be available in the next 10 years.