Three-dimensional analysis of spinal deformity correction in adolescent idiopathic scoliosis: comparison of two distinct techniques

Purpose To compare 3D postoperative deformity correction using two distinct commonly utilized techniques for the treatment of adolescent idiopathic scoliosis (AIS). Methods AIS patients with major thoracic (Lenke 1-2) curves at two sites who underwent deformity correction via posterior spinal instrumented fusion using one of two distinct techniques were retrospectively reviewed. Patients were matched 1:1 between sites for Lenke type (95% Lenke 1) and follow-up time. The "band site" performed posteromedial translation using thoracic sublaminar bands and 5.5-mm rods. The "screw site" performed spine derotation using differential rod contouring with pedicle screws and 5.5-mm rods. 3D measures of deformity from spinal reconstructions were compared between sites. Results Preoperatively, the groups had similar thoracic curve magnitudes (band, 55 +/- 12 degrees vs. screw, 52 +/- 10 degrees;p > 0.05); the "screw site" had less T5-T12 kyphosis (2 +/- 14 degrees vs. 7 +/- 12 degrees,p = 0.05) and greater thoracic apical rotation (- 19 +/- 7 degrees vs. - 14 +/- 8 degrees,p = 0.007). Postoperatively, the "screw site" had greater percent correction (61% vs. 76%,p < 0.001) and kyphosis restoration (p = 0.002). The groups achieved a similar amount of apical derotation (p = 0.9). The "band site" used cobalt chromium rods exclusively; the "screw site" used cobalt chromium (3%) and stainless steel (97%;p < 0.001). The "band site" performed significantly longer fusions. Conclusions Significant variations were found between two commonly utilized techniques in AIS surgery, including rod material, correction mechanisms, and fusion levels. Significantly, a greater 3D deformity correction of the coronal and sagittal planes was observed at the "screw site" compared to the "band site", but with no difference in axial plane correction.