Natural course of moderate adolescent idiopathic scoliosis: a mean 25-year follow-up study

This study aimed to determine the natural course of moderate adolescent idiopathic scoliosis (AIS) in terms of curve progression and health-related quality of life (HRQOL).

The inclusion criteria were nonoperatively treated patients with AIS who had a major curve between 30° and 40° at skeletal maturity (Risser ≥ 4) and age ≥ 30 years at the survey. Fifty-eight patients (55 women) were included (follow-up rate, 37.4%). The mean age was 14.2 years at skeletal maturity and 39.9 years at the survey, with a mean 25.7-year follow-up. The HRQOL scores were compared with age- and sex-matched healthy volunteers (n = 112).

The median magnitude of the major curve was 36.5° at skeletal maturity (n = 58), 40° at the age of 18 years (n = 30), and 45.5° at the survey (n = 47) with a progression rate of 0.5°/year. The major curve at the survey was over 50° in 46.7% of patients, 82.4% of whom had already had major curves ≥ 40° at the age of 18 years. Despite their curve progression, patients demonstrated comparable HRQOL scores with control participants, except for the SRS-22 self-image score (AIS 2.8 vs. Control 3.4, p < 0.001).

Moderate AIS progressed slowly but significantly throughout adulthood. Over 40% of the curves were > 50° during the mean 25-year follow-up period. Although the HRQOL scores of adult patients with moderate AIS at skeletal maturity were comparable with those of the controls, their cosmetic concerns could not be disregarded. Therefore, moderate curves, especially those ≥ 40° at the age approximately 18 years, warrant long-term follow-up.