I got given some Thera-bands by my physiotherapist, and am finding them a great help with my stretching and strengthening exercises. Thera-bands are like long elastic bands, which come in different thicknesses according to how much resistance you need; you can find more info about them here.
I found that using the bands helps prevent you from jerking or making sudden movements during exercise, which could cause a lot of pain and could potentially damage a fused spine. Instead, they provide gentle resistance which helps you to do exercises slowly and smoothly.
One of the best exercises I've found is this one - it really feels good to stretch out crunched-up oblique muscles that have been squished by a lumbar curve
There are all sorts of exercises that you can do with these bands, I really recommend them!
37 years old, diagnosed with infantile idiopathic scoliosis at 6 months old with curves of 62(T) and 40(L) degrees. Casting and Milwaukee braces until surgery at 10 - ant release/pos fusion T1-T12, halo traction. Post op cast and then TLSO. Further surgery at 18 (ant release/pos fusion extended to L3 to include lumbar curve, costoplasty) and 25 (another costoplasty). Fusion extended to L4 at 33 (XLIF with 4 pedicle screws and two short rods). Pre-op curves: 76(T) and 70(L). Post-op curves: 45(T) and 35(L). Diagnosed with Ehlers-Danlos Syndrome aged 34; scoliosis almost certainly due to this rather than being idiopathic.