Evaluation of the efficacy of the K2M MESA Rail™ Deformity System at improving coronal and sagittal correction of the adolescent idiopathic spine deformity in comparison to the side loading DePuy Synthes USS II pedicle screw system. This is a single-center, single-surgeon randomized controlled trial with follow-up evaluations of patients conducted at initial follow-up (2 weeks to 8 weeks), 3 months, 12 months and 24 months post-procedure. Adverse events will be monitored continuously.