Progression in idiopathic scoliosis after conservative treatment.

One hundred patients with idiopathic scoliosis treated conservatively were reviewed for a mean period of 10.6 years after the end of treatment. The majority of curves had increased; 70% between 16 and 20 years of age and 60% after age 20. The mean progression per year was 3 degrees and 2 degrees for single and double curves, respectively, in the first 4 years after the end of treatment and 1 degree and 0.5 degrees, respectively, in adulthood. Curves above 40 degrees increased significantly more than smaller curves. It is concluded that curves of more than 40 degrees, especially thoracic single curves, should be treated operatively in adolescence. Conservative treatment of smaller curves should be continued towards 20 years of age, and the patients should be followed up during early adult life.