Perforation Rate of Pedicle Screws Using Hybrid Operating Room Combined With Intraoperative Computed Tomography Navigation for Adolescent Idiopathic Scoliosis: Impact of Distance From the Reference Frame and Other Risk Factors.

Abstract

Retrospective observational cohort study. Evaluate the perforation rate of pedicle screw (PS) insertion using a hybrid OR combined with intraoperative computed tomography (CT) navigation (hybrid navigation) for adolescent idiopathic scoliosis (AIS) and determine the predictors of misplacement specific to hybrid navigation. Hybrid navigation provides intraoperative three-dimensional fluoroscopic imaging of a quality similar to that of CT. Hybrid navigation is now being used in AIS treatment. However, few reports exist on the perforation rate and predictors of PS perforation using hybrid navigation for AIS. Thirty-eight consecutive patients (34 female and 4 male; mean age: 16.2 years) with AIS who had undergone PS fixation using hybrid navigation were analyzed. PS perforation was evaluated using intraoperative CT after PS insertion. The perforation rate for each level from the anchor reference frame (RF) was measured and compared. We examined for predictors of screw misplacement using baseline patient parameters, instrumented vertebral level, PS insertion order, and vertebral body distance from the RF. Eighteen major perforations (Grade 2 or Grade 3) were recorded among 531 screw insertions (3.4%). The major perforation rate did not increase remarkably until the distance from the RF was 5 vertebral bodies, after which it increased significantly (2.2% vs. 18.4%, P = 0.03). Thirteen patients experienced at least 1 perforation. The subjects with perforations were all female and significantly shorter than those without. Multivariate analysis revealed distance from the RF (+1 vertebra; odds ratio 1.44, P = 0.003) as a predictor of major perforation. The rate of major perforation after PS insertion using hybrid navigation for AIS was relatively low. However, no more than 7 vertebral bodies should be instrumented in a single CT scan to reduce the risk of major perforations. Special attention is also needed for female patients of shorter stature. 3.