The cortical based trajectory for pedicle screw fixation of the lumbar spine is not a novel as it once was. This is a review of the background, indications, advantages, disadvantages of cortical based trajectory pedicle screw fixation with an emphasis on biomechanical evidence and recent clinical studies which only now are just coming to light.

Posterior nonfusion pedicle-screw-based stabilization remains a controversial area of spine surgery. To date, the Dynesys system remains the most widely implanted posterior nonfusion pedicle screw system. We review the history of Dynesys and discuss clinical outcome studies and biomechanical evaluations regarding the Dynesys system. Indications for surgery and controversies are discussed. Recom...

BACKGROUND There have been numerous studies conducted to investigate the pullout force of pedicle screws in bone with different material properties. However, fewer studies have investigated the region of effect (RoE), stress distribution and contour pattern of the cancellous bone surrounding the pedicle screw. METHODS Screw pullout experiments were performed from two different foams and the c...

Introduction Pedicle screw insertion is the mainstay of thora-cic and lumbosacral posterior spinal instrumentation. However, it may be associated with complications such as screw mal-positioning. The purpose of this study was to develop a pilot study to compare the accuracy of robot-guided screw insertion versus hand-guided screw placement for spinal instrumentation. The hand-guided screws were...

The C2 pedicle screw is more biomechanically stable and provides patients with increased postoperative range of motion in comparison to other methods of C2 fixation. However, as a result of the proximity of the C2 pedicle to the transverse foramen, there is a considerable risk of intraoperative morbidity due to vertebral artery injury laterally or vertebral canal breach medially. Other than the...

PSs placed by a spinal surgical fellow (SSF) without prior experience under Attending Spinal Consultant (ASC) supervision from two tertiary spinal centers in Australia were investigated. All patients had postoperative radiographic studies, X-ray (XR) and/or computed tomography (CT), which were graded by two blinded and independent observers. Screws were graded as “acceptable” (contained within ...

STUDY DESIGN Cross-sectional study. PURPOSE The purpose of this study was to evaluate a novel landmark for the cervical pedicle screw insertion point. OVERVIEW OF LITERATURE To improve the accuracy of pedicle screw placement, several studies have employed the lateral mass, lateral vertical notch, and/or inferior articular process as landmarks; however, we often encounter patients in whom we...

STUDY DESIGN Retrospective study. PURPOSE To analyze the quantitative anatomy of C7 vertebra for insertion of lateral mass screws and pedicle screws in Southern Chinese patients. OVERVIEW OF LITERATURE C7 lateral mass is smaller when compared to other subaxial cervical levels, which limits the length of lateral mass screws that can be used. Some studies have suggested pedicle screws for bet...

BACKGROUND There is a high probability of accidental perforation of the vertebral pedicle wall in pedicle screw insertion surgery. A pedicle screw (PS) measurement device with an optical probe has been reported to send out a warning signal before the PS tip breaking the vertebral pedicle wall. METHODS In this study, we explored the detection depth of optical probe in this measurement device, ...

The porcine model is frequently used during development and validation of new spinal devices, because of its likeness to the human spine. These spinal devices are frequently composed of pedicle screws with a reputation for stable fixation but which can suffer pullouts during preclinical implantation on young animals, leading to high morbidity. With a view to identifying the best choices to opti...