Type I DESCRIPTION• S shaped or double curve in which both the thoracic and lumbar curve cross the midline • Lumbar curve larger and stiffer than the thoracic curve TREATMENT• this type of curve is usually fuse down to L4 (via a posterior approach) or down to L3 (anterior approach) Type II DESCRIPTION• S shaped or double curve in which both the thoracic and lumbar curve cross the midline • Thoracic curve larger and stiffer than the lumbar curves. TREATMENT• often a thoracic fusion will suffice for these patients (or down to L1) Type III DESCRIPTION• Thoracic curve crosses midline and lumbar curve does not cross midline TREATMENT• thoracic fusion Type IV DESCRIPTION• Long thoracic curve in which L5 is centered over sacrum but L4 tilts into long thoracic curve TREATMENT• fuse thru L4 Type V DESCRIPTIONThoracic curve and T1 tilts to upper curve TREATMENTUse thru T2; do not assume that the upper (left) thoracic curve is non-structural without proof, and if there is any question, fuse the upper thoracic spine as well as the lower thoracic spine;