Analysis of the upper thoracic curve in surgically treated idiopathic scoliosis-a new concept of the double thoracic curve pattern

The authors reviewed 246 idiopathic scoliosis patients with the upper thoracic curve of more than 20°. Group I (138 patients) had positive T1 tilt and a spinal fusion which was extended over both the upper and lower thoracic curve with the diagnosis of double thoracic curvc. Group II (43 patients) had positive Tl tilt, but the fusion whs limited to the lower thoracic curve. Group III (65 patients) had negative or neutral T1 tilt and the fusion was limited to the lower thoracic curve. The average age at operation was 16.9 years (range, 11.2-36 years) anrl the average length of follow up wss 4, B years (range-, 2-29.5 years), Positive T1 lilt did not correlate well with left shouldor olevation contrary to previous reports, The upper thoracic curve was more rigid than the lower curve in all groups and the lumbar curve was significantly more flexible than the upper and lower thoracic curves in all groups (P< 0.Q5) No significant difference in the flexibility of the upper thoracic curve was found between the groups regardless of the direction of T1 tilt, When only the lower curve was fused (groups II and III), progression of the upper thoracic curve was less than. 5% a net spontaneous correction of the unfused upper curve occurred in tho majority of the ch5bs following tho supine bending study. Correction and fusion on the lower curve (groups II and IIJI aggravated shoulder imbalance of all patients with left shoulder elevation. Based on the findings-of this study, the authors proposed that t?ie diagnosis of idiopathic double thoracic patterns should be limited to those patterns which require fusion of both the upper and lower curves. This pattern of idiopathic scoliosis Includes doub e thoracic curves with loft shoulder elevation and/or a rigid upper thoracic curve.