Robotic Guidance System for Cervical and Thoracolumbar Spinal Surgery

Pre-operative planning and robotic-guided pedicle screw placement is feasible and accurate with clinically acceptable results in cervical and thoracolumbar spinal surgery, according to findings from a prospective study by Isador H. Lieberman, MD, MBA, FRCSC, presented at the International Society for the Advancement of Spine Surgery (ISASS) 19th Annual Conference held April 3 to 5, 2019 in Anaheim, CA.

“Navigational and robotic-guided systems facilitate more efficient and accurate placement of instrumentation during spinal surgeries,” said Dr. Lieberman, who is an orthopaedic and spinal surgeon at Texas Back Institute in Plano, TX. “Pre-operative surgical planning is a key step in the safe use of these tools.”

The goal of the study by Dr. Lieberman and colleagues was to investigate the predictive accuracy of surgical planning using a robotic guidance system in the placement of pedicle screws in cervical spine or thoracolumbar spine surgery.

The researchers prospectively collected data on patients undergoing cervical spine surgery (n=4) and surgical correction of thoracolumbar deformity (n=10). These patients underwent surgery for scoliosis (n=5), kyphosis (n=2), adjacent segment degeneration (n=2), and spondylolisthesis (n=1).

“For the cervical group, we focused on the accuracy of the pedicle screw placement and deviation from the pre-operative plan,” explained Dr. Lieberman, who is also a SpineUniverse editorial board member. “For the thoracolumbar group, we concentrated on the extent of spinal alignment correction as well as comparison of the pre-operative deformity with the planned and post-operative corrections in the coronal and sagittal planes.”

Accuracy was assessed by fusing the pre-operative computed tomography scan showing the planned pedicle screw placement with the post-operative scan showing the actual screw position (see Figure for example). These scans were compared manually by aligning anatomical landmarks on the two scans. Next, the researchers compared the planned versus the actual screw placements in both the axial and sagittal planes at the mid-point of the pedicle, with a resolution of 0.1 millimeters.

Figure. Computed tomography scan comparing the planned trajectory (blue and yellow markings) and executed trajectory (dashed black line) of cervical pedicle screw placement using a robotic guidance system in a patient with cervical deformity. The measurements in pink show the difference between the planned and actual pedicle screw placement. Reprinted with permission from Isador H. Lieberman, MD, MBA, FRCSC.

Cervical Pedicle Screw Placement

“In the cervical group, all of the trajectories and screw positions were clinically acceptable,” Dr. Lieberman said. In the axial plane, the left side screw deviated from the pre-operative plan by 1.1±0.7 mm and the right-side screw deviated by 1.4±1.3 mm. In the sagittal plane, the left side screw deviated from the pre-operative plan by 1.0±0.9 mm and the right-side screw deviated by 1.2±0.7 mm. No inter-operative complications related to the placement of the cervical pedicle screws occurred in this study.

Thoracolumbar Pedicle Screw Placement

“In the thoracolumbar group, the accuracy of planning was within 8° for the coronal Cobb angle and 10° for the sagittal Cobb angle,” Dr. Lieberman explained. Instrumentation under robotic guidance was carried out according to the pre-surgical plan in all patients.

Pre-operatively, the mean coronal Cobb angle was 24.7±16.8°, and the mean sagittal Cobb angle was 20.6±16.6°. The planned coronal Cobb angle after correction was 0°, and the planned sagittal Cobb angle after correction was 32.0±13.8°. Post-operatively, the patients’ mean coronal Cobb angle was 7.7±3.9°, and the mean sagittal Cobb angle was 27.2±12.4°. Thus, the accuracy of planning was 7.7±8.0° for the coronal Cobb angle and 9.8±7.5° for the sagittal Cobb angle.

“The study indicates that the pre-operative planning in robotic-guided placement is feasible and accurate,” Dr. Lieberman concluded. “Robotic-guided screw placement is here to stay. But always remember, robotic surgery is not going to make a bad surgeon good. What it does is make a good surgeon more precise and more efficient.”

Disclosure
Dr. Lieberman is a consultant for Globus, Medtronic, Misonix, Safe Orthopaedics, SI Bone, and Stryker Spine.