Intraoperative Navigation Increases the Projected Lifetime Cancer Risk in Patients Undergoing Surgery for Adolescent Idiopathic Scoliosis

BACKGROUND CONTEXT:Adolescent idiopathic scoliosis (AIS) is a common condition, often requiring surgical correction. Computed tomography (CT) based navigation technologies, which rely on ionizing radiation, are increasingly being utilized for surgical treatment. Although this population is highly vulnerable to radiation, given their age and female predominance, there is little available information elucidating modeled iatrogenic cancer risk. PURPOSE:To model lifetime cancer risk associated with the use of intraoperative CT-based navigation for surgical treatment of AIS STUDY DESIGN/SETTING: This retrospective cross-sectional study took place in a quaternary care academic pediatric hospital in the United States PATIENT SAMPLE: Adolescents aged 10-18 who underwent posterior spinal fusion for a diagnosis of AIS between July 2014 and December 2019 OUTCOMES MEASURES: Effective radiation dose and projected lifetime cancer risk associated with intraoperative doses of ionizing radiation METHODS: Clinical and radiographic parameters were abstracted, including total radiation dose during surgery from flat plate radiographs, fluoroscopy, and intraoperative CT scans. Multivariable regression analysis was used to assess differences in radiation exposure between patients treated with conventional radiography versus intraoperative navigation. Radiation exposure was translated into lifetime cancer risk using well-established algorithms. RESULTS:In total, 245 patients were included, 119 of whom were treated with navigation. The cohort was 82.9% female and 14.4 years of age. The median radiation exposure (in millisieverts, mSv) for fluoroscopy, radiography, and navigation was 0.05, 4.14, and 8.19 mSv, respectively. When accounting for clinical and radiographic differences, patients treated with intraoperative navigation received 8.18mSv more radiation (95% CI: 7.22-9.15, p<0.001). This increase in radiation projects to 0.90 iatrogenic malignancies per 1000 patients (95% CI 0.79-1.01). CONCLUSIONS:Ours is the first work to define cancer risk in the setting of radiation exposure for navigated AIS surgery.  We project that intraoperative navigation will generate approximately 1 iatrogenic malignancy for every 1000 patients treated. Given that spine surgery for AIS is common and occurs in the context of a multitude of other radiation sources, these data highlight the need for radiation budgeting protocols and continued development of lower radiation dose technologies. LEVEL OF EVIDENCE:Therapeutic, III.