A logical coronal pattern classification of 2,000 consecutive idiopathic scoliosis cases based on the Scoliosis Research Society defined apical vertebra

Study Design. Two thousand consecutive idiopathic scoliosis records and radiographs were reviewed for coronal pattern typing and categorization, based on Scoliosis Research Society definitions of the apical vertebra. Apical frequency was determined for each of the patterns identified, and represents a database from a large series of cases for the already accepted Scoliosis Research Society definitions. Objectives. To identify and numerically pattern-type a large series of idiopathic coronal curves, for the basic purpose of written and oral communication. Some pattern types were not described previously. Summary of Background Data. Although spinal deformity must be considered three dimensional for treatment in 1998, no comprehensive, databased, and user friendly coronal or sagittal classification of idiopathic scoliosis has been reported. Methods. Two thousand idiopathic curve patterns from charts and radiographs were reviewed and the coronal patterns categorized by the apical vertebra. The resulting classification was tested for inter- and intraobserver reliability by 12 spine surgeons and 6 orthopedic residents. Apical frequencies were determined for each pattern type. Results. Twenty-one pattern categories were identified, and all were right or left mirror image patterns (except for a quadruple pattern) that permitted separation into 11 types. Incorporating the widely recognized five numbered King types made pattern recognition simple. Interobserver reliability testing was 98.2%. The left single thoracic curve pattern was included in this classification because only 9 [20.4%) of 44 patients with left thoracic curves had intraspinal pathology. Conclusion. Two thousand consecutive idiopathic coronal curve patterns separated into eleven readily identifiable types, and incorporating the widely referenced five King types, makes recognition simple for purposes of identification and communication. Sagittal and 3D factors excluded from this classification are equally important in the process of treatment decisions. Apical frequency data determined in this study lends credence to Scoliosis Research Society definitions for idiopathic curve patterns.