How Does Brain Control The Limb Movement After The Deformity Correction Surgery?

hello and thank you for your time. My 15 year old son has extreme rotational deformity56 degree rotation. in his lower legs and is scheduled for surgery. dr Teitge dearborn, MI is performing the surger(ies) six months apart. he will cut the large bone in lower leg and rotate straight and pin together. My question is: is it a good idea? how does the brain still control the limb after cutting and reattachment? My son has anxiety is 6ft 2in and 270 lbs. thanks for any advice