Primary Hypothesis and expected outcomes: Use of Floseal will reduce blood loss and surgical time in patients undergoing spine surgery for adolescent idiopathic scoliosis (Level-I evidence). Cost benefit analysis will most probably show that the use of Floseal is cost effective. E.g. the value of one allogenic Red Blood Cell unit is 400€. If no red blood cell units are needed instead of the usual three, the reduced blood product use alone will cover the extra costs of Floseal use. In addition, if no allogenic blood infusions are needed, the risk of infections will probably be significantly less. Reduced surgical time and shorter hospital stay may also be cost reducing findings in patients receiving Floseal.