Objective: Operative treatment of adolescent idiopathic scoliosis (AIS) with posterior spinal fusion aims for three-dimensional correction of coronal curve and thoracic kyphosis. Our aim was to compare two different designs of asymmetrical rods in adolescents who underwent a posterior spinal fusion with pedicle screw instrumentation for AIS with an emphasis on thoracic kyphosis restoration.

Methods: This study was made with 76 consecutive adolescents (mean age 15.6 years, SD 2.0). Thirty-nine patients were operated with sagittal reinforced rods and 37 patients were operated with beam-like rods. The clinical and radiological results were assessed preoperatively, postoperatively, and during the follow-up visits at the outpatient clinic 6 months and 2 years after the surgery.

Results: At the last follow-up, the mean (SD) major thoracic curves were 13° (6.2°) and 13° (6.0°) (P = 0.717). Correction percentages were 75% in the sagittal reinforced group and 73% in the beam-like rod group (P = 0.517). The mean (SD) thoracic kyphosis was 24° (11°) and 22° (7.8°) at the two year follow-up in the sagittal reinforced rod group and beamlike rod group (P = 0.517). There was a slight negative correlation between the major curve correction and thoracic kyphosis change in both groups, although this was not statistically significant (R = -0.19, P = 0.094 in the sagittal reinforced rod group, R=-0.16, P = 0.180 in the beam like rod group).

Conclusions: There are no significant differences in the coronal or sagittal deformity restoration in adolescent patients who underwent a posterior spinal fusion with sagittal reinforced rods and beam-like rods for adolescent idiopathic scoliosis.