A 2,210 screw, 5-year study of the use of 3D printed guides to place pedicle screws in adult spinal deformity cases not only found advantages over digital navigation and robotic assist, but the paper was the “Best Paper” at the recent Annual Safety in Spine Surgery Summit.
The study, “Does Pedicle Morphology Affect the Safety and Accuracy of Pedicle Screw Placement Using 3D Printed Guides? A 5-year Single Center Experience with 2,210 Screws Placed for Adult Spinal Deformity Reconstruction,” has been accepted for publication by the International Journal of Spine Surgery.
Study co-author Venu Nemani, M.D., Ph.D. explained to OTW some of the rationale behind this unique research topic, “Watanabe C pedicles have no cancellous channel and Watanabe D pedicles have only a cortical slit. It is difficult to safely place screws into these narrow pedicle types, which are commonly found in the concavity of idiopathic curves which affect both adult and pediatric patients.”
“There are many modalities available to assist with safe placement of spinal instrumentation, the most commonly utilized being fluoroscopy, traditional navigation, and robotic-assisted navigation,” said Dr. Nemani, a spine surgeon at the Center for Neurosciences and Spine, Virginia Mason Franciscan Health in Seattle, Washington.
“Patient-specific 3D printed guides are utilized less frequently but are an intriguing option given they require no capital expenditure and cause very little disruption to the typical workflow for open adult spinal deformity surgery. However, there is limited data available on the safety of using 3D printed guides in adult spinal deformity, especially in cases where there are small pedicles which present challenges for safe placement of screws.”
The researchers designed 3D printed pedicle screw drill guides based on fine cut (1.25mm or less) CT scans. Four adult spinal deformity surgeons with varying degrees of experience placed the guides.
The study reviewed data from 115 patients (age range 18-81 years., mean 62 years) with 2,210 screws placed T1 to L5. The median number of levels instrumented using 3D printed screw guide per case was 11 [IQR 7-12].
The research team collected data from patients diagnosed with adult degenerative scoliosis (n=62), adult idiopathic scoliosis (n=30), Scheuermann kyphosis (n=2), and other complex conditions (n=21).
Overall, there was a 99.5% rate of accurate pedicle screw placement, with a 0% malposition rate in type C and D pedicles. There were no vascular or neurological complications and reoperation related to screw placement.
When OTW asked about any necessary workflow adjustments, Dr. Nemani noted, “Unlike navigation or robotic assisted surgery, there is no intraoperative registration necessary. To use the guides, which are spinal level specific, they are simply placed onto the posterior elements of the level to be instrumented and adjusted until they have a ‘lock and key’ fit, then a high-speed drill is used to create the pedicle trajectory, followed by tapping the channel, followed by screw placement. This workflow allows for two surgeons to place screws simultaneously thereby decreasing the overall time needed during a case for instrumentation placement.”
“More research is necessary to directly compare the accuracy of this technique vs traditional or robotic-assisted navigation, as well as to refine guide design to improve their usage in a variety of clinical situations for instrumentation placement from skull to pelvis.”
