Anterior instrumentation for correction of adolescent thoracic idiopathic scoliosis: historic prospective study.

AIM: To compare the results of anterior instrumentation and standard posterior procedure for correction of adolescent thoracic idiopathic scoliosis.
METHODS: The study included 50 patients with adolescent thoracic idiopathic scoliosis who underwent corrective spinal surgery. Anterior spinal fusion by use of modified Zielke ventral derotation system (anterior approach to spine through thorax) was performed in 25 patients, whereas posterior approach was used in 25 patients. The average preoperative thoracic curve in coronal plane was 66.7 +/- 9.9 degrees and 65.0 +/- 11.7 degrees in the anterior and posterior correction groups, respectively. The median age of patients before surgery was 14 years (range, 12-18) in the anterior and 16 years (range, 13-18) in the posterior correction group. Women-to-men ratio was 22 to 3 in each group. Coronal and sagittal correction, apical vertebral body rotation, rib hump, and rib depression correction were measured before surgery and at the first (30 days after surgery) and at the second follow-up visit (at least 2 years after surgery). Posteroanterior and laterolateral radiographs of the erect spine were used (according to the method of Cobb and Nash-Moe) to assess coronal, sagittal, and horizontal plane corrections. Rib hump and rib depression were measured with Thulbourne-Gillespie measuring device. The differences in scoliosis correction parameters in the two groups were tested with Student two-tailed t test.
RESULTS: In the coronal plane, the thoracic curve of 66.7 +/- 9.9 degrees before surgery in the anterior correction group was reduced to 14.8 +/- 8.7 degrees after surgery (78.1 +/- 12.4% relative correction), and the curve of 65.0 +/- 11.7 degrees in the posterior correction group was corrected to 29.2 +/- 7.8 degrees after surgery (55.1 +/- 8.6% relative correction) (P<0.001). Apical vertebral body rotation correction according to the Nash-Moe classification from 2.0 +/- 0.4 degrees to 0.8 +/- 0.6 degrees was achieved in the anterior correction group (62.0 +/- 26.6% relative correction) and from 1.7 +/- 0.5 degrees to 1.4 +/- 0.5 degrees in the posterior correction group (12.0 +/- 21.8% relative correction) (P<0.001). Rib hump correction from 22.4 +/- 15.5 mm to 5.4 +/- 5.2 mm was found in the anterior correction group (70.9 +/- 26.0% relative correction) and from 25.3 +/- 7.0 mm to 13.6 +/- 6.8 mm (48.4 +/- 16.5% relative correction) in the posterior correction group (P = 0.084).
CONCLUSION: Compared with the standard posterior approach, the anterior approach resulted in better three-dimensional correction of idiopathic thoracic scoliosis.