Original ArticlesAccuracy of Fluoroscopically Assisted Laser Targeting of the Cadaveric Thoracic and Lumbar Spine to Place Transpedicular ScrewsSchwend, Richard M.; Dewire, Peter J.*; Kowalski, Joseph M.†Author Information Departments of Orthopaedic Surgery, University of New Mexico, Albuquerque, New Mexico; *Boston University, Boston, Massachusetts; and †University at Buffalo, Buffalo, New York, U.S.A. Received May 10, 1999; March 1, 2000. Presented at the 33rd Annual Meeting of the Scoliosis Research Society, New York, New York, September 16–20, 1998. Address correspondence and reprint requests to Dr. R. M. Schwend, Department of Orthopaedic Surgery, Carrie Tingley Hospital, University of New Mexico, 1127 University Blvd. NE, Albuquerque, NM 87102-1715, U.S.A. E-mail: email@example.com Journal of Spinal Disorders: October 2000 - Volume 13 - Issue 5 - p 412-418 Buy Abstract A simple and inexpensive method was developed to obtain a coaxial view of the pedicles to assist with screw insertion. The authors evaluated the accuracy of this device to place transpedicular vertebral screws in a human adult cadaver model. A dual radiation targeting system, a laser targeting system for fluoroscopically guided procedures, was developed to provide an accurate surface entry point and angle of approach to radiographic landmarks. After fluoroscopic cross-hair target localization of the coaxial view of the pedicle, X-ray radiation is turned off and the laser beam allows the surgeon to guide the screw through the pedicle. Nine cadaver spines were removed and mounted. Three surgeons, inexperienced in the technique of pedicle screw placement, fitted instruments to 184 pedicles between L5 and T5. A total of 83 lumbar and 101 thoracic pedicles underwent screw placement. After specimen dissection, the degree and location of any screw perforation were measured by direct inspection. Three screws perforated a pedicle, for an error rate of 1.6%. Two lumbar screws (2.4% error) and one thoracic screw (1% error) perforated the pedicle. No screw was more than 1 mm outside the pedicle. Five other screws, four in the thoracic spine and one in the lumbar spine (error rate of 2.7%) were directed too far laterally and perforated the lateral vertebral body. This low rate of pedicle wall cortical perforation by inexperienced surgeons compares favorably with much higher pedicle perforation rates by experienced surgeons when no imaging was used. In conclusion, this in vitro model using a dual radiation targeting system assisted with the accurate placement of transpedicular vertebral screws with minimal radiation exposure. © 2000 Lippincott Williams & Wilkins, Inc.