• Sang Bum Kim, Yougun Won, Hyun Jin Yoo, Lee Jae Sin, John M Rhee, Sang Wook Lee, and Gi-Soo Lee.
• *College of Medicine, Konyang University †Department of Orthopaedic Surgery, Emory University, Atlanta, GA ‡School of Biomedical Engineering, Konyang University.
• Spine. 2017 Jan 13.

Study DesignProspective Clinical Pilot tudy OBJECTIVE.: To confirm the accuracy of thoracic pedicle screw placement by using the unilateral spinous non-covering hook type patient-specific drill template (PSDT) made through rapid prototyping (RP) and to analyze previously reported PSDT designs and their characteristics.Summary Of Background DataPedicle screw fixation is the most common form of the posterior instrumentation of the thoracic and lumbar spine. Various techniques have been introduced to improve pedicle screw placement. Among them, a patient-specific drill template (PSDT) with a preplanned trajectory has been considered a promising solution; however, we don't have consensus on proper character of the template.MethodsPreoperative spiral three-dimensional (3D) computed tomography (CT) was performed on the thoracic spine. The images were stored in DICOM format and transferred to a workstation running MIMICS 17.0 software to generate a 3D reconstruction template for the desired thoracic vertebra. The accurate trajectory and screw diameter and length were calculated with UG Imageware 12.1. The guide template was sterilized and used intraoperatively to assist with the placement of thoracic pedicle screws. After all pedicle trajectory screws had been inserted. We reviewed 12 previous reports and classified them according to the shape and system of PSDT that met the inclusion criteria of the review.ResultsTen screws were placed by using the PSDT without violating the single laminar cortex. There was no violation of the spinal canal or the cortex of pedicle on postoperative CT scans. The results of 13 PSDT types included in the current study suggested that there is no significant difference in accuracy between the PSDTs.ConclusionThe unilateral spinous process noncovering hook type PSDT made through RP provided an accurate trajectory for the thoracic vertebra, and the classification of PSDT in this study could be helpful for further studies.Level Of Evidence5.

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