Georg Schmorl Prize of the German Spine Society (DWG) 2025: Abdominal aortic calcification indicates altered bone microarchitecture and extracellular matrix quality in patients undergoing lumbar fusion surgery

Introduction: Bone quality is crucial for satisfactory spinal surgery outcomes. Abdominal aortic calcification (AAC) has been linked to lower bone mineral density (BMD) and increased fracture risk, but its association with bone microarchitecture and extracellular matrix (ECM) quality remains underexplored. Research question: Is AAC independently associated with bone quality beyond BMD in patients undergoing lumbar fusion surgery? Material and methods: In 139 patients undergoing lumbar fusion surgery, AAC was evaluated on lateral lumbar radiographs using the Kauppila score. BMD was measured by quantitative CT, and iliac crest biopsies were analyzed by micro-CT for microarchitecture and by Fourier-transform infrared imaging (FTIRI) for ECM parameters. Associations were examined using correlation and multivariable regression analyses adjusted for BMD or confounders (age, sex, BMI, smoking, diabetes). Results: Higher AAC severity correlated with lower BMD (r = -0.37, p < 0.001), higher trabecular (r = 0.40, p < 0.001) and cortical tissue mineral density (TMD) (r = 0.29, p = 0.001), lower cortical mineral maturity/crystallinity (MMC, r = -0.26, p = 0.003), and greater cortical (r = 0.27, p = 0.002) and trabecular (r = 0.24, p = 0.005) MMC heterogeneity. In multivariable models, AAC remained independently associated with lower BMD (p = 0.001), higher trabecular TMD (p = 0.02), and higher trabecular MMC heterogeneity (p < 0.001). Discussion and conclusion: Preoperative AAC assessment could be representative for altered bone quality characteristics independently of BMD. Accordingly, AAC scoring could refine preoperative risk assessment and trigger osteologic workup to mitigate complication risk in spinal fusion surgery.