Impact of Pedicle Screw Instrumentation with Addition of Crosslink on Growth of Spinal Canal in Young Children

Abstract

Introduction The use of pedicle screws has been popularized in the treatment of pediatric spinal deformity. Despite many studies regarding the effect of pedicle screws on the immature spine, there is a paucity of data concerning the impact of the screw-rod-crosslink complex on the development of spinal canal in young children. The objective of this study is to determine the influence of the screw-rod-crosslink complex on the development of spinal canal. Materials and Methods This study reviewed 34 patients with congenital scoliosis (14 boys and 20 girls) who were treated with posterior-only hemivertebrectomy and pedicle-screw-based short-segment instrumentation before the age of 5 years. They were followed-up for at least 24 months. Of these patients, 10 underwent only pedicle screw instrumentation without crosslink, and 24 with additional crosslink placement. The vertebrae were divided into three regions as follows: (1) S-CL (screw-crosslink) region, in which the vertebrae were inserted with bilateral pedicle screws and two rods connected with the crosslink; (2) S (screw) region, in which the vertebrae were inserted with bilateral pedicle screws but without crosslink; (3) NS (no screws) region, which comprised vertebrae cephalad or caudal to the instrumented region. The area, anteroposterior and transverse diameters of the spinal canal were measured at all vertebrae on the postoperative and last follow-up computed tomography axial images. The instrumentation-related parameters were also measured, including the distance between the bilateral screws and the screw base angle. The changes in the above measurements were compared between each region to evaluate the instrumentation's effect on the spinal canal growth. Results The mean age at surgery was 37 ± 11 months (range, 21–57 months) and the mean follow-up was 37 ± 13 months (range, 24–68 months). In each region, the spinal canal dimensions significantly increased during the follow-up period. There was no significant difference in the spinal canal growth rate between the S and NS regions or between the S-CL and NS regions. In addition, a comparison of the S-CL and S regions regarding the changes in measurements of the instrumentation construct revealed no significant differences. Conclusion Pedicle-screw-based instrumentation does not cause retardation of the development of spinal canal in young children. Moreover, use of the crosslink added to the screw-rod instrumentation also demonstrates no negative effect on the growth of the spinal canal. Thus, the addition of the crosslink to screw-based instrumentation is recommended to increase fixation stability in growing patients, even in very young pediatric population.