The Influence Of The Lowest Instrumented Vertebra Determination In Posterior Spinal Fusion Treatment For Lenke Type1Adolescent Idiopathic Scoliosis

Objective:To evaluate the influence on the outcomes of posterior spinal fusion in Lenke type1adolescent idiopathic scoliosis by choosing different lowest instrumented vertebra.Material and methods:23lenke type1adolescent idiopathic scoliosis patients who underwent posterior spinal fusion from July2009to July2012in our hospital were selected for this retrospective study. All of them were classified by choosing different lowest instrumented vertebra:"TV"(group A) and lowest EV or SV(group B). Radiographic measurement included main Cobb angle, trunk shift (TS), lumbar lordosis (LL), lowest instrumented vertebrae tilting (LIVT), LIV distal angulation (LIVA), the amount of the fusion levels and other parameters on the standing anterior-posterior radiographs before and after surgery. The statistical differences of preoperative and postoperative data of two groups were compared.Results:The means of main Cobb angles in group A and B were respectively40.84±7.48°and 50.00±16.73°before the surgery, both of which had no significant differences (P>0.05). The cobb angles were effectively corrected after PSF surgery in both groups, and the cobb angles turned to10.66±5.74°and17.57±8.50°, but the correcting rate did not differ statistically (P>0.05) while did within either group (P<0.001). The pre-surgery LIVT value were respectively17.61±4.33°and13.08±5.59°in two groups, which showed no significant differences, respectively compared with the post surgery value4.35±2.14°and2.21±2.57°.(P>0.05).However the pre-and post LIVT did differ significantly in either group (P<0.001). Similarly, the LIVA values had no significant differences between two groups neither pre-and post surgery.(pre-:3.26±2.10°and4.12±2.78°, post:0.551±0.53°and1.25±1.11°)(P>0.05), but had statistical significance when compared within group (P<0.001).For other observation targets like TS, SVA, LL and the amount of fusion levels, no significant differences were displayed within or between groups. Choosing TV can save average1.10±0.83flexible vertebrae.Conclusion:In the posterior spinal fusion treatment for Lenke type1AIS, choosing TV or lowest EV or SV as LIV can achieve similar and satisfactory correcting effect. Choosing TV as LIV can save more flexible vertebrae.