The purpose of this study is to gain initial experience and information for proper planning and conduct of a confirmatory study (a multi-centre single-blind comprehensive cohort study of bracing).

The study has been completed.

Inclusion Criteria:

1. Diagnosis of AIS
2. Age ≥10 years
3. Risser sign 0-2
4. Cobb's angle 20 deg to <25 deg with documented deterioration of at least 5 deg within the past 4 months (with a maximum of 10 days deviation), or 25 deg to <30 deg

Exclusion Criteria:

1. History of treatment of AIS
2. >= 1 year postmenarchal (for girls only)
3. Physical or mental disability to adhere to bracing
4. Diagnosis of musculoskeletal or development illness that might be responsible for the spinal curvature
5. Structural thoracic scoliosis with apex above T7 (Note these patients are not suitable for under-arm brace)
6. Difficulty to read, understand, and complete the study questionnaires
7. Any criteria, which, in the opinion of the investigator, suggests that the subject would not be compliant with the study protocol