Anterior instrumentation for thoracolumbar adolescent idiopathic scoliosis: do structural interbody grafts preserve sagittal alignment better than morselized rib autografts?

Abstract

Study design: This is a retrospective, sequential cohort study of 34 patients treated by anterior instrumented fusion with single solid rod, single screw constructs with at least 2-year follow-up. Sixteen of the patients received structural grafts as interbody spacers in disc levels below T12, while the other 18 patients received only morselized rib autograft.

Objective: To determine if structural interbody grafts preserve sagittal alignment better than morselized rib autograft.

Summary of background data: Some studies have shown that structural grafts are more effective in preserving sagittal alignment, while others have found them to be no more effective than morselized rib graft.

Methods: Anterior-posterior radiographs were measured for primary, secondary, and fractional Cobb curves, and C7-sacrum plumb lines. Lateral radiographs were measured for: T5-HIV (highest instrumented vertebrae), instrumented levels, LIV (lowest instrumented vertebrae)-S1, T12-LIV, and T12-S1 angles, C7-sacrum plumb lines, and LID-A (lowest instrumented disc-angle).

Results: The increase in kyphosis from preoperative to follow-up radiographs of the angle between T12-LIV was significantly more for the patients with morselized rib graft compared with those with structural grafts, 9 degrees and 1 degree, respectively (P < 0.05).

Conclusions: The structural grafts placed in disc spaces below T12 were able to maintain sagittal alignment over this region, while the spines that received only morselized rib graft collapsed into kyphosis.