Selection of distal fusion levels in the surgical management of thoracolumbar/lumbar adolescent idiopathic scoliosis

Abstract

To investigate the efficacy and safety of a new method which determines the exact distal fusion level in the treatment of adolescent idiopathic scoliosis (AIS) with posterior pedicle screw fixation and to assess its clinical outcome. This prospective clinical study analyzed 31 AIS patients who met the inclusion criteria enrolled from July 2005 to September 2008. Based on the principle of our new criteria for selection of distal fusion level of AIS, all patients had posterior spinal fusion and instrumentation with pedicle screws. Cobb angle of the curve, tilt angle of the LIV, intervertebral angle and trunk shift were measured and analyzed. Preoperative (42 + or - 17) degrees of thoracic curve was corrected to (12 + or - 7) degrees , with a curve correction of 70.6%. Preoperative (44 + or - 7) degrees of lumbar curve was corrected to (9 + or - 4) degrees , with a curve correction of 80.2%. The trunk shift were significantly improved from (13 + or - 8) mm to (9 + or - 7) mm before and after surgery respectively (P < 0.05). The tilt angles of the LIV before and after surgery were (20.8 + or - 5.7) degrees and (1.5 + or - 3.1) degrees respectively. The thoracic Cobb angle was (14 + or - 8) degrees and the lumbar Cobb angle was (9 + or - 5) degrees at latest follow up. The changes were of significance in the tilt angle of the LIV after surgery compared with that before surgery (P = 0.000). This angle averaged (0.8 + or - 3.7) degrees at final follow up, but the change was not significant compared with that after surgery (P > 0.05). This is an effective method with the advantage of shortening the fusion level, reserving the distal motion segments and easing segmental degeneration adjacent to the fusion area.