Interpretation and utility of traction radiography in scoliosis surgery - Analysis of patients treated with Cotrel-Dubousset instrumentation

Study Design. An analysis of a standardized method of traction radiography for the evaluation of reducibility of scoliosis. Objectives. To determine whether and how preoperative traction radiography can provide objective information and to compare traction radiography with supine side-bending og radiography. Summary-of Background Data. Flexibility of scoliosis deformity remains arbitrary concept. No objective method of preoperative evaluation of reducibility has been established. Methods. The utility of a standardized method of traction radiography was evaluated in 74 patients with idiopathic scoliosis who were aged 14-22 years and treated with Cotrel-Dubousset instrumentation. Results. In thoracic curves, the postoperative Cobb angle-was highly correlated with the preoperative Cobb angle in traction (r = 0.82). However, such correlation was much lower with lumbar curves (r = 0.54). The reducibility of the thoracic curve by traction as expressed by the ratio to the original curve was dependent on the magnitude of the original curve (P = 0.005), and this parameter proved less informative than the absolute angle values. Time-related analysis of 30 patients who were observed for more than 5 years revealed that the high correlation between the preoperative angle of thoracic curves in traction and their postoperative angle decreased with the follow-up time (r = 0.80-0.65). A comparison of traction radiography and supine side-bending radiography showed that these two tests were practically equivalent in terms of evaluating the reducibility of curves. Conclusion. The results provide an objective interpretation of traction radiographs for Scoliosis.