1188: Aortic Wall Shear Stress May Be a Protective Factor Against Development of Spinal Osteoproliferation

Background/Purpose: Diffuse idiopathic skeletal hyperostosis (DISH) is often characterized by new bone formation along the right anterolateral spinal column, particularly in the thoracic region (1, 2). We aimed to investigate the influence of the anatomical right-sided position of the aorta on the localization of osteoproliferation in patients with DISH.

Methods: Computed tomography (CT) examinations involving the thoracic region, performed between 2014 and 2024, were re-evaluated for DISH by an experienced musculoskeletal radiologist in patients whose reports included the terms “dextrocardia,” “situs inversus,” or “right aortic arch.” Those under 18 years of age, with inadequate imaging, or "with dextrocardia and a left aortic arch" were excluded. Patient sex and age at the time of imaging were recorded. The Resnick and Niwayama criteria  were used to identify classical DISH (1), while the Kuperus criteria were applied for early-stage DISH (2).

Results: Of the 214 patients reviewed, a total of 83 patients were included in the final analysis. Imaging modalities included chest CT (n=60), cardiac CT (n=10), thoracic CT angiography (n=6), thoracoabdominal CT (n=4), and spinal CT (n=3). Of the final cohort of 83 patients 60% were male, with a mean age of 33 ± 18 years at the time of CT. Of these, 58 had dextrocardia with a right aortic arch, while 25 had levocardia with a right aortic arch. Changes consistent with DISH were observed in 8 of 83 patients (9.6%) with a right aortic arch. Early DISH findings were detected in seven of these eight patients (87.5%). All osteoproliferative changes were localized to the left side, except in one patient, where they were present on both the upper right thoracic and lower left thoracic regions. Sex distributions were similar between patients with DISH (62.5% male) and those without DISH (60% male), but the mean age at imaging was significantly higher in the DISH group (61 ± 11 years vs. 30 ± 16 years, p< 0.001). The age distribution of patients in the DISH group was as follows: one patient (12.5%) was under 50, two patients (25%) were between 50 and 60, four patients (50%) were between 61 and 70, and one patient (12.5%) was between 71 and 80 years of age.

Conclusion: In classic DISH patients with right-sided osteoproliferation, this localization has been shown to be more closely related to the position of the aorta rather than the heart. The inverse relationship between aortic wall stress and DISH localization may serve as a guide for future studies aimed at preventing osteoproliferation development due to repetitive mechanical stress elsewhere.

References:
1. Resnick D, Niwayama G. Radiographic and pathologic features of spinal involvement in diffuse idiopathic skeletal hyperostosis (DISH). Radiology. 1976;119(3):559-68.
2. Kuperus JS, Oudkerk SF, Foppen W, Mohamed Hoesein FA, Gielis WP, Waalwijk J, et al. Criteria for Early-Phase Diffuse Idiopathic Skeletal Hyperostosis: Development and Validation. Radiology. 2019;291(2):420-6.