BURHAN ORAL GÜDÜ, SUNA DİLBAZ
Comprehensive Medicine - 2025;17(1):29-35
Objective: Assessment of laminar anatomical parameters required for rigid fixation of the lumbar isthmus with intralaminar screws using computed tomography (CT). Materials and Methods: Retrospective lumbar CT scans of 36 adult patients were analyzed. The parameters of the ideal laminar screw trajectory line required for isthmic defect fixation were determined using 3D multiplanar reconstruction, and linear and angular parameters were measured. The laminar screw length (LSL), the width of the thinnest part of the lamina (LW), the transverse distance of the screw entry into the lamina relative to the midline (TD), sagittal (SA) and coronal (CA) screw application angles were evaluated bilaterally at all lumbar levels. Results: The mean age of the patients was 22 years. The LSL had similar values at the levels L13 (3536 mm), with a slight decrease at L4 and L5 (3332 mm). The LW increased from L1 to L4 (79 mm), with a slight decrease observed at L5 (8 mm). The TD increased steadily from L1 to L5 (5610 mm). The SA was similar at L13 (23°25°), with a marked increase toward L4 and L5 (30°40°). The CA increased consistently from L1 to L5 (6°20°). Conclusion: For rigid intralaminar screw fixation, optimal angular and linear screw application parameters should be carefully reviewed in preoperative CT studies to increase the laminar cortical bone attachment of the screw and prevent potential neurologic injury.
