a: A single thoracic curve (Lenke 1). Disc T11/T12 opens in supine bending. T11 is distal LIV. In anteroposterior standing radiograph the apex is disc T8/T9. There are three vertebrae (T9, T10,T11) distal to the apex and therefore three proximal vertebrae (T6, T7, and T8) need to be included in the proximal arm. b: Radiographs and clinical pictures preoperatively and at 5-year follow-up.