Efficacy of En Bloc Direct Vertebral Body Derotation (Dvbd) in Idiopathic Scoliosis Treatment

Abstract

Introduction Vertebral axial rotation in horizontal plane is a component of spinal deformity in scoliosis. Greater axial rotation is related with inclination to curve progression, contributes to rib hump development. Therefore the correction of axial deformity appears as an obvious component of scoliosis correction. However clinical efficiency and complication risk of derotation maneuvers is still not established. The object of the study was to assess horizontal correction obtained with en bloc direct vertebral body derotation (DVBD) and the influence of the maneuver on coronal and sagittal correction of the spine in patients undergoing surgical scoliosis correction. Material and Methods 36 patients after surgical correction of idiopathic scoliosis were included into study. Authors analyzed two groups; adolescents and adults. All patients underwent posterior fusion with pedicle screws only instrumentation. 15 (20 curves) patients were corrected by rod derotation only and 21 (26 curves) underwent rod derotation and direct en bloc vertebral derotation (DVBD). Measurements according to Cobb method were performed on X-rays obtained before and post surgery - coronal plane curves, sagittal profile (T2-T12, T5-T12, L1-S1). Spine flexibility was assessed of prone bending X-rays. Axial rotation was determined on CT scans obtained intraoperatively (O-Arm, Medtronic) and postoperative CT scan. Rotation assessment was done according to the method described by Aaro and Dahlborn. Results The comparison of axial rotation prior to correction and post correction revealed decrease of axial apical vertebral rotation in both DVBD and non DVBD groups. However in DVBD group vertebral derotation was greater than in non DVBD group and it was confirmed in statistic analysis. Amount of axial derotation was similar in both adults and adolescents. Analysis of coronal curves showed statistically significant better correction in (DVBD) group and obviously better correction was possible in flexible than stiff curves. DVBD did not improve but also did not decrease kyphosis comparing to pre op measurements and results from non DVBD group. This statement concerned both T2-T12, T5-T12 measurements. Neither flexibility nor stiffness of the curves influenced kyphosis results. Conclusion Direct vertebral body derotation is a relevant maneuver to improve correction in idiopathic scoliosis, either in coronal or sagittal plane. It may be useful technique in adolescent as well as adult patients.