Low Radiation Protocol for Intraoperative Robotic C-Arm Can Enhance Adolescent Idiopathic Scoliosis Deformity Correction Accuracy and Safety

Abstract

Study design: Retrospective case-series study.

Objectives: To assess (1) low cone beam CT (CBCT) mediated intraoperative navigation to limit radiation exposure without compromising surgical accuracy, and (2) the potential of intraoperative C-arm CBCT navigation to augment pedicle screw (PS) placement accuracy in AIS surgery compared to pre-surgery CT-based planning.

Methods: The first part involved a prospective phantom study, comparing radiation doses for conventional CT, and standard (6sDCT) and a low dose (5sDCT) Artis Zeego^®-imaging. Next, 5sDCT- and 6sDCT-navigation were compared on PS accuracy and radiation exposure during AIS correction. The final part compared surgical AIS deformity correction through intraoperative 5sDCT navigation to a matched cohort treated using conventional pre-surgery CT-scans for navigation. Outcome parameters included operation time, skin dose (SD), dose area product (DAP), intraoperative blood loss, postoperative complications, and PS deviation rates.

Results: The phantom study demonstrated a reduction in radiation for the 5sDCT protocol. Moreover, 5sDCT-imaged patients (n = 15) showed a significantly lower SD (-27.41%) and DAP (-30.92%), without compromising PS accuracy compared with 6sDCT-settings (n = 15). Finally, AIS correction through intraoperative CBCT C-arm navigation (n = 27) significantly reduced screw deviation rates (6.83% versus 10.75%, P = .016) without increasing operation times, compared with conventional CT (n = 37).

Conclusions: Intraoperative navigation using a CBCT C-arm system improved the accuracy of PS insertion and reduced surgery time. Moreover, it reduced radiation exposure compared with conventional CT, which was further curtailed by adapting the low-dose 5sDCT protocol. In short, our study highlights the benefits of intraoperative CBCT navigation for PS placement in AIS surgery.

Keywords: artis zeego; cone beam CT; idiopathic scoliosis; navigation; radiation dose; screw perforation.

Figure 1.

Illustrative overview of imaging and navigation equipment described in this study. (A) O-arm™ Surgical Imaging System (Medtronic Inc, Memphis, TN, USA; not used), (B) Robotic C-arm system Artis Zeego^® (Siemens AG, Forchheim, Germany), (C) StealthStation^® S7^® (Medtronic, Memphis, TN, USA), and (D) Magnus Operating Table System (Maquet, Rastat, Germany) within a hybrid operating room.

Figure 2.

(A) Radiophotoluminescence glass dosimeter on anthropomorphic phantom at thoracic vertebrae level 8 (Th8); [1] Right side, [2] Right chest, [3] Left chest, [4] Left side, and [5] Dorsal side. (B) Skin dose (SD) measured at each site using conventional computed tomography (CT), or cone beam CT (CBCT) using 6sDCT or 5sDCT settings.

Figure 3.

Comparing navigation images from conventional CT and intraoperative CBCT scan. Pictures represent sagittal and axial views of representative AIS spines (A) pre- and (B) post-surgical instrumented deformity correction. For a representative animation of the CBCT 3D images see Video 1. (CBCT: cone-beam computed tomography, CT: computed tomography). Video 1. Example of spine 3D reconstruction using our 5sDCT CBCT scan technique of spine pre- and post-surgical correction.