Treatment decisions are primarily based on the skeletal maturity of the patient (or rather, how much more growth can be expected) as well as the degree of curvature.
The cause of idiopathic scoliosis is unknown (idiopathic literally means 'cause unknown'), but the way curves behave is fairly well understood. The younger the patient and the bigger the curve, the more likely the curve is to progress.
There are essentially three treatment options for adolescents with scoliosis: observation, bracing, and scoliosis surgery. There have been large trials of other forms of treatments, none of which have been shown to be effective. Electrical stimulation, physical therapy, chiropractic manipulation, osteopathic manipulation, or other manual treatments have not been shown to reduce the curvature or to prevent progression.
Because idiopathic scoliosis is considered a deformity, scoliosis treatment is largely centered on reducing or limiting the progression of the deformity and is not focused on treatment of pain.
However, having said all that there are many treatments available that are non surgical for Scoliosis.
When I had my surgery in 1989 there were no other options available as my curve had progressed too far, so I would be interested to hear from anyone that has been down the non surgical road.