Department of Orthopedics，Changhai Hospital，Second Military University，Shanghai，200433，China

English Keywords:Adolescent idiopathic scoliosis  Corrective surgery  Bilateral interval pedicle screw fixation  Pedicle

English Abstract:

  【Abstract】 Objective：To investigate the clinical efficacy of the bilateral interval pedicle screw placement for Lenke 1 adolescent idiopathic scoliosis（AIS）.Method：36 patients（7 males and 29 females） with Lenke 1 AIS（mean age，15.3 years） underwent posterior fusion using bilateral interval pedicle screw placement.All patients had preoperative coronal Cobb angle of main thoracic curve less than 75° and the flexibility greater than 50%.The following variables including pre-and post-operative sagittal and coronal Cobb angles，the distance between the C7 plumbline and the center sacral vertical line（CSVL），the distance between the C7 plumbline and the perpendicular line drawn from the superior posterior endplate of the S1 vertebral body[sagittal sacral vertical line（SSVL）]，rib hump（RH），apical rib spread difference（ARSD），apical vertebral body-rib ratio（AVB-R） were meassured and the clinical outcomes were analyzed.Result：The average operation time was 176min（range，150-240min），and the average blood loss was 840ml（range，460-1100ml）.No neurovascular injury was noted.1 case was complicated with left pleural effusion，and 2 cases were complicated with superficial wound infection 2 weeks after operation.Coronal Cobb angle of major curve decreased significantly from 56.7°±8.0° preoperatively to 14.1°±6.0° of postoperatively（P<0.05）.There was no significant difference between the postoperative thoracic curve and that at the final follow-up（Cobb angle 17.2°±3.2°，P>0.05）.The thoracic sagittal Cobb angle decreased significantly from 28.9°±7.9° preoperatively to 21.9°±10.6° postoperatively（P<0.05）.There was no significant difference between postoperative thoracic kyphosis and that at the final follow up（Cobb angle 24.3°±5.1°，P>0.05）.The distance from the C7 plumbline to the SSVL decreased from -11.7±12.1mm to -1.4±9.4mm（P<0.05）.There was no significant difference between postoperative distance and that at the final follow up（-2.7±4.7mm，P>0.05）.RH decreased from 37.7±5.8mm to 19.3±6.9mm（P<0.05），ARSD decreased from 20.1±6.6mm to 8.1±4.7mm（P<0.05），and AVB-R decreased from 1.56±0.16 to 1.22±0.20（P<0.05）.There were no differences between pre-，post-operation and final follow up with regard to the distance from C7 plumbline to the CSVL（P>0.05）.No instrument failure was noted during the follow up period.Conclusion：Bilateral interval pedicle screw placement can ensure good three-dimensional correction for mild to moderate Lenke 1 AIS.