Quadrilateral Segmental Analysis (QSA): A Calibration-Free Geometric Method for Detecting Lumbar Spondylolisthesis

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27 Oct 2026 0 comments

Background/Objectives: On standing lateral radiographs, millimetre measurements of vertebral slip depend on magnification and calibration; slip percentage is scale-free but is usually reported in coarse Meyerding grades. In this exploratory derivation study, we introduce quadrilateral segmental analysis (QSA), a calibration-free geometric method for detecting anterolisthesis. Methods: In 50 patients with degenerative spondylolisthesis from the PROGRES cohort, a blinded observer drew the L1-S1...