COMPARISON OF THE USE OF SUPINE BENDING AND TRACTION RADIOGRAPHS IN THE SELECTION OF THE FUSION AREA IN ADOLESCENT IDIOPATHIC SCOLIOSIS

Study Design. A study was done to evaluate the use of voluntary supine side bending radiographs and Risser table traction radiographs in ado lescent patients undergoing posterior spinal fusion for idiopathic sco liosis. Objectives. To compare the usefulness of supine side bending a nd traction radiographs in assessing curve flexibility and determining fusion levels in patients undergoing posterior spinal fusion for adol escent idiopathic scoliosis. Summary of Background Data. Supine side b ending radiographs have been used in the preoperative evaluation and f usion area. Traction films have been used to determine the flexibility of large curves and neuromuscular curves where active side bending is not possible. No study to date has compared the use of these films in patients with adolescent idiopathic scoliosis undergoing surgery. Met hods. Seventy-five patients with more than a 2-year follow-up period a fter surgery were included in this study. Preoperative radiographs inc luded a standing posteroanterior and lateral film and both supine maxi mal voluntary side bending films and a traction film done on a Risser table. A preoperative review of these radiographs was done to determin e curve flexibility and fusion levels. At follow-up evaluation, the pa tients were examined for any evidence of decompensation or ''adding-on '' of levels. Result. For curves less than 60 degrees, side bending ra diographs showed greater curve correction than traction radiographs, w hereas the opposite was true for curves greater then 60 degrees. For K ing I and II curves, side bending radiographs were superior for determ ination of lumbar curve flexibility and for distinguishing these two t ypes of curves. On traction radiographs, the stable vertebra was 1.4 v ertebral levels higher than on the standing film. When the fusion leve l was moved proximally because of the traction radiograph, decompensat ion or ''adding-on'' commonly occurred. Conclusions. Supine bending ra diographs are superior to traction radiographs for assessing curve fle xibility except for curves more than 60 degrees. The selection of the distal extent of fusion based on the traction radiograph gave a large number of poor results. The selection of fusion levels in adolescent i diopathic scoliosis is best determined by a combination of standing po steroanterior and lateral radiographs and the supine maximum voluntary bend films.