Full-rotation Three-dimensional Intraoperative Imaging during Spinal Procedures

June 28, 2011 | Emerging Technology Reports


Proprietary names: O-arm Imaging System; StealthStation Treon System; StealthStation S7 System

Generic names: Cone beam computed tomography (CT) with three-dimensional (3D) reconstruction; computer-assisted image guidance; intraoperative imaging; image guidance; image-guided surgery; intraoperative navigation; multidimensional x-ray imaging; surgical imaging; 3-D fluoroscopy

Spinal surgeons use pedicle screws during spinal fusion procedures to affix rods and plates to the spine; their placement often requires millimeter accuracy.1 Pedicle screw misplacement can cause neurologic and vascular complications. Lateral misplacement can lead to hardware failure or pseudoarthrosis due to poor fixation, which can necessitate revisional surgery.2 Misplacement rates as high as 40% were reported in 1996.3

In the mid-1990s, spinal surgeons began using image-guidance techniques to accurately identify critical structures (i.e., arteries, nerves) and optimize pedicle screw placement in unexposed or partially exposed spinal structures (i.e., vertebral body, pedicle).1 Initially, spinal surgery patients underwent preoperative imaging procedures (i.e., computed tomography CT, magnetic resonance imaging, x-ray) to provide diagnostic information to the surgeon and conventional x-ray imaging during surgery to verify placement of pedicle screws.4 However, these imaging techniques provide only two-dimensional (2-D) views, so determining the trajectory of the screw in three dimensions using these methods was not possible.

Currently, intraoperative imaging during spinal surgery in most hospitals involves standard fluoroscopic guidance (C-arm fluoroscopy) with 2-D imaging.5 This technology is also limited in that it does not provide an image of the true three-dimensional (3-D) anatomy of the patient and cannot be used to treat complicated cases or deformities or to perform minimally invasive surgery.6 As an alternative to 2-D fluoroscopy imaging, some hospitals use 3-D fluoroscopy and intraoperative CT or 3-D fluoroscopy in combination with surgical navigation to provide 3-D imaging during spinal procedures.6 Navigation systems convert the data from the imaging system into a computerized image, which is projected onto a monitor to provide real-time updates of instrument location and trajectory in reference to the operative images.

Repeated use of fluoroscopy during spinal surgery may result in significant radiation exposure to the patient and surgical staff.7 CT images obtained preoperatively for comparison to real-time patient anatomy or postoperatively to confirm implant positioning result in additional radiation exposure. Developers of new intraoperative imaging systems aim to provide high-resolution, multiplanar views while minimizing radiation exposure.5 Furthermore, improvements in intraoperative imaging may allow spinal surgeons to perform complex spinal procedures that involve instrumentation using minimally invasive techniques.1 The focus of this report is full-rotation 3-D intraoperative imaging using the O-arm Imaging System (Medtronic Navigation, Louisville, CO, USA) during spinal surgery.

Studies primarily report use of full-rotation 3-D intraoperative imaging during spinal fusion procedures. Common indications for spinal fusion are trauma, degenerative disease, or correction of a scoliosis deformity.8 Nationally representative data collected for the U.S. National Inpatient Sample identified 222,549 primary posterior spine fusion and 12,474...

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