Adolescent Idiopathic Scoliosis: A New Classification to Determine Extent of Spinal Arthrodesis *

An understanding of the three-dimensional nature and spectrum of spinal deformity is a prerequisite to the use of segmental spinal arthrodesis, and the determination of the number of levels to be fused in the management of adolescent idiopathic scoliosis (AIS). The new Lenke system is not entirely comprehensive in utilizing objective criteria to consider AIS as a three-dimensional deformity. Rotation is of paramount importance when differentiating structural curves from nonstructural curves. This system was created, however, at a time when cross-sectional imaging was not universally available, and an attempt to create a reliable lumbar alignment modifier within the axial plane was not successful. The new Lenke system was designed to standardize treatment. An assessment of 7 operative AIS cases reviewed by 28 scoliosis surgeons resulted in high variability in selection of both operative approach and fusion level, illustrating the lack of standardized treatment paradigms at the time.