Your daughter being 13 years of age with a 50 degree curve most likely will need to be fixed. I assume this is a scoliosis and not a hyperkyphosis (a curve from the side view).
The reason scoliosis needs to be surgically fixed in a young girl is that the curve will most likely advance. Over the years with a significant spinal deformity- real problems will occur that you don’t want your daughter to face. Yes- scoliosis surgery replaces a curved but supple spine with a straight (or straighter) but stiff spine at the levels fixed.
I never think a second opinion is a bad idea and there are many places in Texas that do a good job with scoliosis surgery. Good luck.
Dr. Corenman