Curve Progression in Adolescent Idiopathic Scoliosis With a Minimum of 2 Years’ Follow-up After Completed Brace Weaning With Reference to the SRS Standardized Criteria

Study Design A retrospective study. Objectives To investigate curve evolution after brace weaning in adolescent idiopathic scoliosis (AIS) with reference to the Scoliosis Research Society (SRS) criteria. Summary of Background Data Previous studies mainly focused on curve evolution during bracing in AIS. However, curve progression after brace weaning was not well addressed. Methods Braced AIS girls followed up for at least 2 years after brace weaning were reviewed. All patients had radiographs at initial visit, brace weaning, 6 months, 1 year, and 2 years after brace weaning, and last follow-up. Curve progression after brace weaning was separately defined as increase in Cobb angle <5 degrees and curve magnitude <45 degrees. The predictors for curve progression were identified using the independent t test. Results 200 AIS girls were reviewed. The average duration of follow-up after brace weaning was 51.4 ± 25.6 months. Compared with brace weaning, at 6 months, 1 year, 2 years and last follow-up after brace weaning, 50 (25.0%), 60 (30.0%), 93 (46.5%), and 87 (43.5%) patients, respectively, had curve progression >5 degrees; 0 (0%), 0 (0%), 2 (1%), and 2 (1%) patients, respectively, had surgery recommended; among those with Cobb angle ≤40 degrees at brace weaning, 7 (4.0%), 11 (6.3%), 16 (9.2%), and 18 (10.3%) patients, respectively, had Cobb angle >45 degrees; the mean progression magnitudes were 2.6 ± 5.8, 3.5 ± 5.8, 5.1 ± 6.5, and 5.4 ± 7.4 degrees, respectively; and the mean progression rates were 0.34 ± 0.83, 0.16 ± 0.56, 0.13 ± 0.39, and 0.006 ± 0.28 degrees/month, respectively. Cobb angle at brace weaning was associated with increase in Cobb angle <5 degrees (p =.033) and curve magnitude >45 degrees (p <.001) after brace weaning. Conclusions Curve progression after brace weaning is observed in 43.5% AIS patients. The highest risk occurs within 6 months after brace weaning whereas Cobb angle remains stable after 2 years’ follow-up. High Cobb angle at brace weaning indicates high risk of curve progression after brace weaning. Level of Evidence Level III.