Open access preprint Thoracic, Lumbar, and Sacral Pedicle Screw Placement Using Stryker-Ziehm Virtual Screw Technology and Navigated Stryker Cordless Driver 3: Technical Note, by Satarasinghe et al. Preprints 2018.
Object. Utilization of pedicle screws (PS) for spine stabilization is common in spinal surgery. With reliance on visual inspection of anatomical landmarks prior to screw placement, the free-hand technique requires a high level of surgeon skill and precision. Three-dimensional (3D) computer-assisted virtual neuronavigation improves the precision of PS placement and minimize steps. Methods. Twenty-three patients with degenerative, traumatic, or neoplastic pathologies received treatment via a novel three-step PS technique that utilizes a navigated power driver in combination with virtual screw technology. 1) Following visualization of neuroanatomy using intraoperative CT, a navigated 3-mm match stick drill bit was inserted at anatomical entry point with screen projection showing virtual screw. 2) Navigated Stryker Cordless Driver with appropriate tap was used to access vertebral body through pedicle with screen projection again showing virtual screw. 3) Navigated Stryker Cordless Driver with actual screw was used with screen projection showing the same virtual screw. One hundred and forty-four consecutive screws were inserted using this three-step, navigated driver, virtual screw technique. Results. Only 1 screw needed intraoperative revision after insertion using the three-step, navigated driver, virtual PS technique. This amounts to a 0.69% revision rate. One hundred percent of patients had intraoperative CT reconstructed images to confirm hardware placement. Conclusions. Pedicle screw placement utilizing the Stryker-Ziehm neuronavigation virtual screw technology with a three step, navigated power drill technique is safe and effective.
Accuracy Assessment of Pedicle and Lateral Mass Screw Insertion Assisted by Customized 3D-Printed Drill Guides: A Human Cadaver Study, by Pijpker et al.Operative Neurosurgery (2018).
Accurate cervical screw insertion is of paramount importance considering the risk of damage to adjacent vital structures. Recent research in 3-dimensional (3D) technology describes the advantage of patient-specific drill guides for accurate screw positioning, but consensus about the optimal guide design and the accuracy is lacking.
To find the optimal design and to evaluate the accuracy of individualized 3D-printed drill guides for lateral mass and pedicle screw placement in the cervical and upper thoracic spine.
Five Thiel-embalmed human cadavers were used for individualized drill-guide planning of 86 screw trajectories in the cervical and upper thoracic spine. Using 3D bone models reconstructed from acquired computed tomography scans, the drill guides were produced for both pedicle and lateral mass screw trajectories. During the study, the initial minimalistic design was refined, resulting in the advanced guide design. Screw trajectories were drilled and the realized trajectories were compared to the planned trajectories using 3D deviation analysis.
The overall entry point and 3D angular accuracy were 0.76 ± 0.52 mm and 3.22 ± 2.34°, respectively. Average measurements for the minimalistic guides were 1.20 mm for entry points, 5.61° for the 3D angulation, 2.38° for the 2D axial angulation, and 4.80° for the 2D sagittal angulation. For the advanced guides, the respective measurements were 0.66 mm, 2.72°, 1.26°, and 2.12°, respectively.
The study ultimately resulted in an advanced guide design including caudally positioned hooks, crosslink support structure, and metal inlays. The novel advanced drill guide design yields excellent drilling accuracy.