Traditional treatment at a Cobb angle of 26-50 degrees consists of corrective therapy: to correct the abnormal curvature as much as possible and stop the progression of the curvature, a redressing orthosis or a replacement corset is used for grade 3 scoliosis. 
There are various types of corsets for corrective fixation of the spinal column and its stabilization, but one of the most effective over the past 40 years has been the Chenot corset for grade 3 scoliosis in children and adults. The corset is made individually, taking into account the anatomical features of each patient, using an X-ray image with the corresponding measurements of the trunk or its 3D scanning. The orthosis corrects the scoliotic arch in three planes at once, which makes it easier to breathe and avoid muscle atrophy.
Treatment of scoliosis of the 3rd degree is complex, and it combines: Exercise therapy - special exercises for scoliosis of the 3rd degree; with S-shaped scoliosis - gymnastics according to Katharina Schroth (with asymmetric exercises); yoga and therapeutic massage (which helps to normalize the tone of the muscles of the back and lower back); physiotherapy treatment (with the use of electromyostimulation). Manual therapy can be used to improve the extensibility of muscle tissue and increase the range of motion of the joints of the spine. 
Experts recommend swimming for grade 3 scoliosis, which has a positive effect on the entire musculoskeletal system. What exercises in the pool are best done, orthopedists will tell you, see the publication - Exercises for the back in the pool 
Surgical treatment used for scoliosis in many cases makes it possible to correct the deformity of the spinal column by increasing the stability of the vertebral joints. In children, scoliosis with a curvature angle of 45 degrees or more requires surgical intervention. What kind of surgery is necessary for grade 3 scoliosis depends on the type of curvature, and it can be spinal fusion with metal implants, epiphysis spondylodesis, corrective vertebrotomy, etc. More information in the materials:
What can not be done with grade 3 scoliosis?
Experts' answers to questions frequently asked by patients or parents of children with a given degree of spinal deformity.
- How long can you sit or stand in one position?
No more than 20-25 minutes, after which the position of the body must be changed.
- Can I carry something in one hand or a bag on the shoulder?
Better not to.
- How to sleep with grade 3 scoliosis?
You need to sleep on a semi-rigid mattress, ideally on an orthopedic one.
The heel height should be 3-4 cm maximum.
- Is childbirth possible with grade 3 scoliosis?
If a woman with this disease becomes pregnant and was able to maintain the pregnancy until the required time, then the delivery is carried out by cesarean section.
- What sport is prohibited for grade 3 scoliosis?
Football, all contact and power sports, athletics, artistic gymnastics, acrobatics for scoliosis of the 3rd degree are excluded.
- Are they drafted into the army with scoliosis?
Even with grade 2 scoliosis, conscripts are considered unfit for military service, and grade 3 scoliosis and the army are simply incompatible.
- Scoliosis grade 3 and disability
With a given degree of scoliotic deformity, disability is given.