Yu B Chen

Kunming Medical College, Yün-nan, Yunnan, China

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Publications (4)6.19 Total impact

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    ABSTRACT: With the rapid increase in the use of thoracic pedicle screws in scoliosis, accurate and safe placement of screw within the pedicle is a crucial step during the scoliosis surgery. To make thoracic pedicle screw placement safer various techniques are used, Patient-specific drill template with pre-planned trajectory has been thought as a promising solution, it is critical to assess the efficacy, safety profile with this technique. In this paper, we develop and validate the accuracy and safety of thoracic transpedicular screw placement with patient-specific drill template technique in scoliosis. Patients with scoliosis requiring instrumentation were recruited. Volumetric CT scan was performed on each desired thoracic vertebra and a 3-D reconstruction model was generated from the CT scan data. The optimal screw size and orientation were determined and a drill template was designed with a surface that is the inverse of the posterior vertebral surface. The drill template and its corresponding vertebra were manufactured using rapid prototyping technique and tested for violations. The navigational template was sterilized and used intraoperatively to assist with the placement of thoracic screws. After surgery, the positions of the pedicle screws were evaluated using CT scan and graded for validation. This method showed its ability to customize the placement and the size of each pedicle screw based on the unique morphology of the thoracic vertebra. In all the cases, it was relatively very easy to manually place the drill template on the lamina of the vertebral body during the surgery. This method significantly reduces the operation time and radiation exposure for the members of the surgical team, making it a practical, simple and safe method. The potential use of such a navigational template to insert thoracic pedicle screws in scoliosis is promising. The use of surgical navigation system successfully reduced the perforation rate and insertion angle errors, demonstrating the clear advantage in safe and accurate pedicle screw placement of scoliosis surgery.
    Medical & Biological Engineering 03/2012; 50(7):751-8. · 1.76 Impact Factor
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    ABSTRACT: To develop and validate the efficacy and accuracy of a novel drill template for cervical pedicle instrumentation. A CT scan of the cervical vertebrae was performed, and a 3D model of the vertebrae was reconstructed using MIMICS 10.01 software. The 3D vertebral model was then exported in STL format, and opened in a workstation running UGS Imageware 12.0 software to determine the optimal pedicle screw size and orientation. A virtual navigational template was established according to the laminar anatomic trait, and physical navigational templates were manufactured using rapid prototyping. The navigational templates were used intraoperatively to assist in the placement of cervical pedicle screws. In all, 84 pedicle screws were placed, and the accuracy of screw placement was confirmed with postoperative X-rays and CT scans. Eighty-two screws were rated as Grade 0, 2 as Grade 1, and no screws as Grade 2 or 3. Hence, safer screw positioning was accomplished with the drill template technique. This study demonstrates a patient-specific template technique that is easy to use, can simplify the surgical act, and generates highly accurate cervical pedicle screw placement. The advantages of this technology over traditional techniques are that it enables planning of the screw trajectory to be completed prior to surgery, and that the screw can be sized to fit the patient's anatomy.
    Computer Aided Surgery 01/2011; 16(5):240-8. · 0.78 Impact Factor
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    ABSTRACT: STUDY DESIGN.: Prospective trial. OBJECTIVE.: To develop and validate a novel, patient-specific navigational template for cervical pedicle placement. SUMMARY OF BACKGROUND DATA.: Owing to the narrow bony anatomy and the proximity to the vertebral artery and the spinal cord, cervical instrumentation procedures demand the need for a precise technique for screw placement. PATIENT.: Specific drill template with preplanned trajectory has been thought as a promising solution for cervical pedicle screw placement. METHODS.: Patients with cervical spinal pathology (n = 25) requiring instrumentation were recruited. Volumetric CT scan was performed on each desired cervical vertebra and a 3-dimensional reconstruction model was generated from the scan data. Using reverse engineering technique, the optimal screw size and orientation were determined and a drill template was designed with a surface that is the inverse of the posterior vertebral surface. The drill template and its corresponding vertebra were manufactured using rapid prototyping technique and tested for violations. The navigational template was sterilized and used intraoperatively to assist with the placement of cervical screws. In total, 88 screws were inserted into levels C2-C7 with 2 to 6 screw in each patient. After surgery, the positions of the pedicle screws were evaluated using CT scan and graded for validation. RESULTS.: This method showed its ability to customize the placement and the size of each screw based on the unique morphology of the cervical vertebra. In all the cases, it was relatively very easy to manually place the drill template on the lamina of the vertebral body during the surgery. The required time between fixation of the template to the lamina and insertion of the pedicle screws was about 80 seconds. Of the 88 screws, 71 screws had no deviation and 14 screws had deviation <2 mm, 1 screw had a deviation between 2 to 4 mm and there were no misplacements. Fluoroscopy was used only once for every patient after the insertion of all the pedicle screws. CONCLUSION.: The authors have developed a novel patient-specific navigational template for cervical pedicle screw placement with good applicability and high accuracy. This method significantly reduces the operation time and radiation exposure for the members of the surgical team. The potential use of such a navigational template to insert cervical pedicle screws is promising. This technique has been clinically validated to provide an accurate trajectory for pedicle screw placement in the cervical spine.
    Spine 12/2009; 34(26):E959-66. · 2.16 Impact Factor
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    ABSTRACT: The great accuracy of computer-assisted operative systems for pedicle screw insertion makes them highly desirable for spinal surgeries. However, computer-assisted pedicle screw placement is expensive, and the learning curve for these techniques is significant. We have developed a novel method of spinal pedicle stereotaxy by reverse engineering (RE) and rapid prototyping (RP) and have validated the method's accuracy by cadaveric and clinical study. A volumetric CT scan was performed on each desired lumbar vertebra and a three-dimensional (3D) reconstruction model was generated with MIMICS 10.1, while the optimal screw size and orientation were determined using UG Imageware 12.1. A drill template was created using UG Imageware 12.1, with a surface that is the inverse of the vertebral surface. The drill template and its corresponding vertebra were manufactured using RP. The method was tested on six cadavers without any fluoroscopic control at surgery. Eventually, the technology was applied in six clinical cases. The accuracy of the drill template was confirmed by preoperatively drilling the screw trajectory into the vertebra biomodel. In the cadaveric experiment, 36 pedicle screws were inserted and no pedicle perforation was observed by postoperative CT scan. In the six clinical patients, the best fit for positioning the template was easily found manually during the operation. The required time between fixation of the template to the lamina and insertion of the pedicle screw into each segment (one or two vertebrae) was 1-2 min. In total, 22 screws were inserted into T12-L5, with two to four screws/patient. No misplacement occurred using the individual templates. Fluoroscopy was used only once after all the pedicle screws had been inserted. The method significantly reduces operation time and radiation exposure for the members of the surgical team. The authors have developed a novel computer-assisted drill template for lumbar pedicle screw placement. This method has shown its ability to customize the placement and size of each screw, based on the unique morphology of the lumbar vertebra. The potential use of drill templates to place lumbar pedicle screws is promising.
    International Journal of Medical Robotics and Computer Assisted Surgery 03/2009; 5(2):184-91. · 1.49 Impact Factor