RF90#103
Rapid Fire
A Comprehensive Framework for the Radiographic Assessment of Lumbar Pedicle Screw Instrumentation: Review of Literature and a New Proposed Criteria Assessment
Borriwat Santipas, MD. (Department of Orthopedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand and Spine Ortho Clinic, Melbourne, VIC, Australia); Hiroto Makino, MD., Ph.D. (Department of Orthopaedic Surgery, Faculty of Medicine, University of Toyama, Toyama, Japan and Spine Ortho Clinic, Melbourne, VIC, Australia), Rebecca DeCarlo, MD., (Atrium Health, Department of Neurosurgery, Charlotte, NC, USA and Spine Ortho Clinic, Melbourne, VIC, Australia), and John YS Choi, MBChB (Spine Ortho Clinic, Melbourne, VIC, Australia)
Background: Accurate pedicle screw placement is critical for spinal stability and neural safety. Widely used assessment systems, such as the Gertzbein–Robbins classification and its modifications, primarily quantify cortical breach magnitude using 2-mm increments or binary in–out criteria. While these approaches standardize reporting, they fail to account for biomechanical and trajectory-related factors that influence construct stability and long-term outcomes.
Objective: To review existing pedicle screw accuracy assessment systems, identify their limitations, and propose a novel evidence-based, multidimensional classification incorporating mechanical and trajectory considerations relevant to contemporary image-guided and robotic spine surgery.
Methods: A narrative review of the literature was performed using PubMed, Embase, and Scopus to identify studies addressing pedicle screw accuracy, breach grading systems, biomechanical fixation parameters, and trajectory-related outcomes. Existing classification systems were critically evaluated for clinical relevance and methodological limitations. Radiographic and biomechanical evidence was synthesized to inform development of a new multidimensional assessment framework.
Results: Current grading systems largely focus on breach extent and overlook critical parameters such as pedicle fill ratio, screw length optimization, sagittal alignment, and facet joint preservation. Biomechanical evidence demonstrates that screw trajectories parallel to the superior endplate reduce cyclic loading and loosening, while optimized screw-to-pedicle occupancy improves pull-out strength. Based on these findings, the proposed framework integrates three domains: (1) cortical breach integrity, (2) dimensional optimization, and (3) trajectory alignment, including axial convergence, sagittal orientation, and facet joint integrity.
Conclusions: Existing pedicle screw accuracy assessments are limited by a narrow radiographic focus. The proposed multidimensional classification provides a comprehensive and clinically relevant framework that integrates safety, biomechanics, and trajectory considerations, aligning with the precision requirements of modern minimally invasive and robotic-assisted spine surgery.
