128 Application of Cortical Bone Trajectory Instrumentation for Juvenile and Adolescent Idiopathic Scoliosis. (1st August 2016) - Patel, Vishal J.
Abstract: INTRODUCTION: Idiopathic scoliosis is the lateral curvature of the spinal column greater than 10° with no established etiology. In skeletally immature pediatric patients, risk of progression is associated with the severity of curvature. It has been estimated that this risk is nearly 90% for patients with curvatures exceeding 50°, and this is typically the severity at which surgical management is indicated. Current surgical techniques rely heavily on posterior instrumentation with pedicle screw systems. Cortical bone trajectory (CBT) screws are increasingly used in the adult lumbar spine. CBT screws utilize a significantly different medial-to-lateral, inferior-to-superior trajectory compared with traditional pedicle screws. They require less tissue dissection and shorter length screws. Additionally, biomechanical studies have demonstrated greater pullout strength of CBT screws in comparison with traditional pedicle screws owing to greater purchase of cortical bone. These features make them attractive for use in pediatric lumbar spine; however, there are few clinical or radiographic studies regarding CBT screw fixation in children. The authors examined the lumbar spine in pediatric patients to define morphometric differences compared with adults, establish guidelines for CBT instrumentation in idiopathic scoliosis, and define potential limitations of this technique in the pediatric age group. METHODS: Measurements of the trajectory diameter, length, lateral angle to the vertebral sagittal plane, and cephalad angle to the vertebral horizontal plane were obtained from 3-dimensional reconstructions of abdominal and pelvic CT scans of 30 pediatric patients. RESULTS: For most levels and measurements, results in boys and girls did not differ significantly; the few values that were significantly different are not likely to be clinically significant. However, younger (<12 years of age) and older children (>12 years of age) differed significantly in screw acceptance size at multiple levels. A screw acceptance analysis found that all patients >4 years of age could accept at least a 4 × 20 mm CBT screw. CONCLUSION: Cortical bone trajectory screws appear to be a useful proposed fixation strategy in JIS and AIS. This may offer an alternative to pedicle screw instrumentation for the surgical management of idiopathic scoliosis.