A New Operative Classification of Idiopathic Scoliosis: A Peking Union Medical College Method

Study Design. A retrospective radiographic study on the type of surgically treated idiopathic scoliosis, with a prospective study on the reliability of the type-related fusion guide. Objectives. To identify and classify surgically treated idiopathic scoliosis, and define its related fusion levels by a new classification system. Summary of Background Data. Some classification methods for idiopathic scoliosis have been suggested. However, poor intraobserver reproducibility and interobserver reliability were experienced in these studies, and were not appropriate for guiding surgical planning. Methods. A total of 427 surgically treated idiopathic scoliosis cases were reviewed. Preoperative and postoperative standing anteroposterior, lateral, and preoperative supine side-bending radiograph were analyzed using the Scoliosis Research Society definition of scoliosis and curve apex. The resulting classification was tested for intraobserver reliability and interobserver reliability, and by 6 surgeons. Apical frequencies were determined for each type, and prospective surgical testing of the new type and its related fusion guide was performed. Results. Three major types and 13 subtypes were identified, of which the Peking Union Medical College type I accounted for 56.62%, type II 42.16%, and type III 1.22%. The interobserver reliability testing was 85% (kappa coefficient 0.832), while intraobserver reproducibility was 91% (kappa coefficient 0.898). Each type had its corresponding fusion levels. A prospective study of 152 cases was performed according to the classification. All of these cases were followed over 18 months, and no postoperative decompensation was noted. Conclusion. The Peking Union Medical College classification of idiopathic scoliosis is one system to combine each type with its corresponding fusion level, and it had much higher interobserver reliability and intraobserver reproducibility than the King system. Further prospectivestudies would help to clarify and expand this system.