• Levent Karapinar, Nuri Erel, Hasan Ozturk, Taskin Altay, and Ahmet Kaya.
• Department of Orthopaedics and Traumatology, Izmir-Tepecik Training and Research Hospital, Izmir, Turkey. lkarapinar@yahoo.com
• J Spinal Disord Tech. 2008 Feb 1;21(1):63-7.

Study DesignComputerized tomography (CT) analysis of in vivo pedicle screw placement to determine their exact position in relation to the pedicle in thoracolumbar region (T10-L3).ObjectiveTo evaluate the clinical accuracy of the placement of thoracolumbar pedicle screws with a free hand technique after reviewing preoperative imaging.Summary Of Background DataCT scans have been used in research clinical settings to evaluate pedicle screw placement in thoracolumbar spine.Material And MethodsNinety-eight consecutive patients who underwent posterior stabilization using 640 transpedicular screws by 1 surgeon from T10 to L3 were analyzed. The mean age was 36.1+/-15.1 (13 to 73) years at the time of surgery. Pedicle screws were inserted using anatomic landmarks; specific entry sites, preoperative anteroposterior/lateral radiographs, and CT imaging were used to guide the surgeon. After preparation of entry point, a pedicle probe was carefully advanced free hand down the pedicle into the body. Careful palpation of all bony borders (flour and 4 pedicle walls) was performed before placement the screw. Postoperative CT scans were used to evaluate the position of all pedicle screws inserted. Screw cortical penetration was graded on the basis of anatomy (the wall penetrated) and distance of the penetration, with 2 mm of interval.ResultsThe number of screws inserted at each level were as follows: T10 (n=55), T11 (n=124), T12 (n=118), L1 (n=91), L2 (n=146), and L3 (n=106). Analysis of these pedicle screws using postoperative CT scans confirmed 37 (5.8%) violated screws, including 12 medial, 18 lateral, 2 superior, 1 inferior, and 4 anterolateral vertebral body penetrations. No neurologic, vascular, or pleural injuries occurred. No screws required postoperative repositioning.ConclusionsPedicle screw placement with a free hand technique after reviewing preoperative imaging seems to be accurate, reliable, and safe adjunct for the placement of thoracolumbar spine screws.

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