A pilot morphometric analysis of lumbar vertebrae to identify fluoroscopic biomarkers

Introduction: Variability in lumbar vertebral anatomy and clinical outcomes necessitate a more patient-specific approach to perform lumbar medial branch radiofrequency neurotomy (LMBRFN). To identify patient-specific fluoroscopic biomarkers, a comprehensive understanding of 3D bony anatomy and its fluoroscopic appearance is required. The objective of this first-of-its-kind pilot morphometric study was to use 3D modeling technology to evaluate these correlations and identify fluoroscopic biomarkers that may distinguish optimal parallel cannula placement for LMBRFN. Methods: The lumbar vertebrae and sacra (n = 60) were photographed, reconstructed in 3D and imaged with fluoroscopy. Individual 3D model of the lumbar vertebra and sacrum were imported into Blender3D and custom code was used to simulate fluoroscopic imaging for correlational morphometric analysis with photos and radiographs. Virtual cannulae were placed parallel to the lateral necks of the superior articular processes of each 3D model to determine the cannula angle classification and identify the fluoroscopic biomarker. Results: A total of 85 out of 118 simulated cannula placements (72.0%) were classified as parasagittal (15-deg). Qualitative analysis of the parasagittal vs traditional vertebrae found a potential differentiating fluoroscopic biomarker based on morphometric parameters. In the 85 cases of simulated cannula placement with parasagittal trajectory, 70 (82.0%) had this fluoroscopic biomarker. For the 33 cases with traditional cannula trajectory, only 10 (30.0%) had the fluoroscopic biomarker. Conclusions: This morphometric analysis study demonstrates that 3D modelling with fluoroscopic imaging analysis is feasible to identify fluoroscopic biomarkers. Future clinical and morphometric studies are needed to develop robust fluoroscopic biomarkers to advance interventional pain medicine towards a personalized medicine paradigm based on a patient's specific anatomy.