ANALYSIS OF THE UPPER THORACIC CURVE IN SURGICALLY TREATED IDIOPATHICSCOLIOSIS - 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-degrees. Group I (138 patients ) had po sitive T1 tilt and a spinal fusion which was extended over both the up per and lower thoracic curve with the diagnosis of double thoracic cur ve. Group II (43 patients) had positive T1 tilt, but the fusion was li mited to the lower thoracic curve. Group III (65 patients) had negativ e or neutral T1 tilt and the fusion was limited to the lower thoracic curve. The average age at operation was 15.9 years (range, 11.2-35 yea rs) and the average length of follow-up was 4.8 years (range, 2-29.5 y ears). Positive T1 tilt did not correlate well with left shoulder elev ation contrary to previous reports. The upper thoracic curve was more rigid than the lower curve in all groups and the lumbar curve was sign ificantly more flexible than the upper and lower thoracic curves in al l groups (P< 0.05). No significant difference in the flexibility of th e upper thoracic curve was found between the groups regardless of the direction of T1 tilt. When only the lower curve was fused (groups II a nd III), progression of the upper thoracic curve was less than 5-degre es, and spontaneous correction of the unfused upper curve occurred in the majority of the cases following the supine bending study. Correcti on and fusion on the lower curve (groups II and III) aggravated should er imbalance of all patients with left shoulder elevation. Based on th e findings of this study, the authors proposed that the diagnosis of i diopathic 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 double thoracic curves with left sho ulder elevation and/or a rigid upper thoracic curve.