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

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.