ObjectiveTo investigate the effect of vectors associated with main curve and overall curves preoperatively and postoperatively on coronal trunk balance（CTB） in adolescent idiopathic scoliosis (AIS).MethodsWe retrospective analyzed 22 AIS patients who received posterior pedicle screw and rod system treatment.All patients had pre- and postoperative spin radiograph of standing upright anteroposterior and lateral views, as well as preoperative supine left and right side-bending radiographs.Using the vector concept in physics, which has size and direction, we analyzed the vectors associated with all curves and the offset of coronal C7 plumb line (C7PL) relative to center sacral vertical line (CSVL) pre- and postoperatively.ResultsIn preoperation, the vector of C7PL-CSVL was significantly associated with the vector of major curve(r=0.447, P<0.05).In preoperation, the vector of C7PL-CSVL was significantly associated with the vector of overall curves (r=0.510,P<0.01).Correction amount of major curve was not significantly associated with the change amount of C7PL relative to CSVL(C7PL-CSVL) distance (P>0.05).Correction rate of major curve was not significantly associated with the change rate of C7PL-CSVL distance(P>0.05).In pre- and postoperation, the angle of curve had no significant effect on the offset distance of C7PL-CSVL(P>0.05).ConclusionsThe key of intervention (brace,operation) is to prevent the whole spine offset to the convex direction of major curve and overall curves in AIS patients, which tends to have coronal trunk imbalance.There is no direct relationship between the cobb angle of curves and the coronal trunk balance pre- or postoperatively in AIS patients.