The accuracy of
We present an analysis of manual and computer-assisted preoperative
Background. Accurate insertion of pedicle screws in scoliosis patients is a great challenge for surgeons due to the severe deformity of thoracic and lumbar spine. Meanwhile, mal-position of pedicle screw in scoliosis patients could lead to severe complications. Computer-assisted navigation technique may help improving the accuracy of screw placement and reducing complications. Thus, this meta-analysis of the published researches was conducted concentrating on accuracy of
Introduction. Pedicle screw fixation is considered gold standard as it provides stable and adequate fixation of all the three columns of spine. Mal-placement of screws in dorso-lumbar region, using fluoroscopic control only, varies from 15% to 30 %. The aim of this study was to determine whether accuracy of
The use of cervical pedicle screws as anchors in posterior reconstruction surgery has not been widely accepted due to the neurological or vascular injury. We thus sought to investigate the accuracy of free-handed
Pedicle screws fixation to stabilise lumbar spinal fusion is the gold standard for posterior stabilisation. Pedicle screws are today positioned in free hand or under fluoroscopic guidance with an error from 20% up to 40–50%, which can determine the inefficacy of treatment or severe damages to close neurologic structures. Surgical navigation drastically increases screws placement accuracy. However its clinical application is limited due to cost reasons and troubles related to the presence of a localiser in the OR and the need to perform a registration procedure before surgery. An alternative image guided approach is the use of patient specific templates similar to the ones used for dental implants or knee prosthesis. Until now, the proposed solutions allow to guide the drill, and in some cases, as templates fit completely around vertebra, they require the complete removal of soft tissues on a large portion of the spine, so increasing intervention invasiveness. To reduce the soft tissue demolition, some authors proposed a fitting based on small “V shape” contact points, but these solutions can determine instability of the template and the reacting of wrong stable positions. In our solution, after spine CT acquisition, each vertebra is segmented using a modified version of ITK-SNAP software, on which the surgeon plans screws positioning and finally the template is designed around the chosen trajectories, using a tool which allows to insert cylinders (full or empty) in the segmented images. Each template, printed in ABS, contains two hollow cylinders, to guide the screws, and multiple contact points on the bone surface, for template stabilisation. We made an in-vitro evaluation on synthetic spine models (by Sawbones) to study different template designs. During this first step an ongoing redesign allowed to obtain an optimal template stability and an easy template positioning to minimise the intervention invasiveness. A first contact point, which fits on the sides of the spinous process, is used to simplify template alignment. The other 4 contact points, which consists of cylinders (diameter 5 mm), fit exactly on spine surface in correspondence to the vertebra's lamina and articular processes to stabilise the template in an unique position. Templates can be used to guide not only the drill, but also Kirschner wires, to guide cannulated screws. After the Kirschner wires insertion the template can be dismounted for its removal (the direction of the kirschner wires are not parallel). After the definitive template design an ex-vivo animal test on 2 porcine specimens has been conducted to evaluate template performance in presence of soft-tissue in place. The specimens have been scanned with CT, we realised a total of 14 templates and we performed the insertion of 28 Kirschner wires. We evaluated that after the soft tissue dissection and the bone exposure, the template can be easily positioned in the right unique position, with no additional tissue removal compared to the traditional approach, requiring just removal of the soft tissue under the small contact points using an electric cutter. The surgeon evaluated (and corrected) some wrong stable template positions when not all the contact points were in contact with the bone surface. The post-op evaluation was made with a CT scan that showed 1 cortical pedicle violation (3.5%) (grade II according to the FU classification).
Introduction. Pedicle screw fixation commonly uses a manual probe technique for preparation and insertion of the screw. However, the accuracy of obtaining a centrally located path using the probe is often dependent on the experience of the surgeon and may lead to increased complications. Fluoroscopy and navigation assistance improves accuracy but may expose the patient and surgeon to excessive radiation. DSG measures electrical conductivity at the tip and provides the surgeon with real-time audio and visual feedback based on differences in tissue density between cortical and cancellous bone and soft tissue. The authors investigated the effectiveness of DSG for training residents on safe
The objective of this paper is to demonstrate the difference in post-operative complication rates between Computer-assisted surgery (CAS) and conventional techniques in spine surgery. Several studies have shown that the accuracy of
To introduce a new robot-assisted surgical system for spinal posterior fixation which called TiRobot, based on intraoperative three-dimensional images. TiRobot has three components: the planning and navigation system, optical tracking system and robotic arm system. By combining navigation and robot techniques, TiRobot can guide the screw trajectories for orthopedic surgeries. In this randomised controlled study approved by the Ethics Committee, 40 patients were involved and all has been fully informed and sign the informed consent. 17 patients were treated by free-hand fluoroscopy-guided surgery, and 23 patients were treated by robot-assisted spinal surgery. A total of 190 pedicle screws were implanted. The overall operation times were not different for both groups. None of the screws necessitated re-surgery for revised placement. In the robot-assisted group, assessment of pedicle screw accuracy showed that 102 of 102 screws (100%) were safely placed (<2 mm, category A+B). And mean deviation in entry point was 1.70 +/− 0.83mm, mean deviation in end point was 1.84 +/− 1.04mm. In the conventional freehand group, assessment of pedicle screw accuracy showed that 87 of 88 (98.9%) were safely placed (<2 mm, category A+B), 1 screw fall in category C, mean deviation in entry point was 3.73 +/− 2.28mm, mean deviation in end point was 4.11 +/− 2.31mm. This randomised controlled study verified that robot-assisted
Introduction. The education of residents in the proper
Summary. Optimum position of pedicle screws can be determined preoperatively by CT based planning. We conducted a comparative study in order to analyse manually determined pedicle screw plans and those that were obtained automatically by a computer software and found an agreement in plans between both methods, yet an increase in fastening strengths was observed for automatically obtained plans. Hypothesys. Automatic planning of pedicle screw positions and sizing is not inferior to manual planning. Design. Prospective comparative study. Introduction. Preoperative planning in spinal deformity surgery starts by a proper selection of implant anchors throughout the instrumented spine, where pedicle screws provide the optimum choice for bone fixation. In the case of severe spinal deformities, dysplastic pedicles can limit screw usage, and therefore studying the anatomy of vertebrae from preoperative images can aid in achieving the safest screw position through optimal fastening strength. The purpose of this study is to compare manually and automatically obtained preoperative pedicle screw plans. Materials and Methods. CT scans of 17 deformed thoracic spines were studied by two experienced spine deformity surgeons, who placed 316 pedicle screws in 3D using a software positioning tool by aiming for the safest trajectory that permitted the largest possible screw sizes. The resulting manually obtained screw sizes, trajectory angles, entry points and normalised fastening strengths were compared to those obtained automatically by a dedicated computer software that, basing on vertebral anatomy and bone density in 3D, determined optimal screw sizes and trajectories. Results. Statistically significant differences were observed between manually and automatically obtained plans for screw sizes (p < 0.05) and trajectory angles (p < 0.001). However, for automatically obtained plans, screws were not smaller in diameter (p < 0.05) or shorter in length (p < 0.001), while screw normalised fastening strengths were higher (p < 0.001). Conclusions. In comparison to manual planning, automatically obtained plans did not result in smaller screw diameters or shorter screw lengths, which is in agreement with the definition of the pull-out strength, but in different screw trajectory angles, which is reflected by higher normalised fastening strengths. Captions. Fig. 1. Visual comparison among automatically obtained (green colour) and manually defined
While image guidance and neuro-navigation have enabled a more accurate positioning of pedicle implants, robot-assisted