Comparison of circular and sagittal reinforced rod options on the sagittal balance restoration in adolescents undergoing pedicle screw instrumentation for idiopathic scoliosis.

OBJECTIVE: Pedicle screw instrumentation is widely used for spinal deformity correction and fusion in adolescents for idiopathic scoliosis. The goal is to achieve and sustain good alignment in all three plains. We compared two different cobalt-chromium (CoCr) rod designs with different stiffness, in regard to the coronal and sagittal balance restoration in adolescents operated for idiopathic scoliosis.

MATERIAL AND METHODS: A prospective comparative study of 90 consecutive children (mean age (SD) 15.6 years (2.1)) operated at an adolescent age for idiopathic scoliosis undergoing posterior spinal fusion using bilateral segmental PSI with 6.0 cobalt-chromium rods. Fifty-four children (43 females) were operated using circular rods and 36 (27 females) with sagittal reinforced rods with a two year follow-up.

RESULTS: Preoperative major coronal curves were similar and at two year follow-up (FU) 11° (5.0) and 17° (7.2) with correction percentages of 78% (10) and 69% (12) in the circular and reinforced rod groups (p<0.01). Thoracic kyphosis at two year FU measured 16°(7) and 21° (6) in the circular and reinforced rod groups (p<0.01). The number of patients with hypokyphosis was lower in the reinforced rod group at two year FU (p=0.02). In the reinforced rod group there was a negative correlation between coronal correction and thoracic kyphosis (r= -0.52, p<0.01).

CONCLUSIONS: Both circular and sagittal reinforced 6.0mm CoCr rods provide adequate coronal correction for adolescents with idiopathic scoliosis. The use of sagittal reinforced rods provided better thoracic kyphosis restoration and lower the risk for postoperative hypokyphosis.