Vascular Calcification Amplifies Limb Flexion-Induced Arterial Deformations and Causes Intermittent Vessel Pinching

OBJECTIVE: We aimed to investigate the role of arterial calcification in intensifying femoropopliteal artery (FPA) deformation under limb flexion. BACKGROUND: Peripheral artery disease (PAD) is characterized by reduced blood flow to the lower extremities, often associated with FPA obstructions. Arterial calcification is a key contributor to poor outcomes in PAD. It stiffens arteries and may exacerbate kinking and lumen collapse during limb flexion. METHODS: 84 bent-leg and 84 straight-leg computed tomography angiography (CTA) reconstructions from 32 PAD patients were used to quantify arterial foreshortening, tortuosity, bending, and lumen area reduction. Calcification was characterized using calcium volume, circumferential involvement, and Hounsfield Unit (HU) values. RESULTS: Arterial foreshortening during limb flexion averaged 6±2% in walking postures and 9±3% in sitting postures, while tortuosity values were 0.08±0.02 and 0.14±0.03, respectively. Minimum arterial bending radii were 49±53 mm in walking and 14±10 mm in sitting postures, with median radii of 60±50 mm and 20±15 mm, respectively. Calcified FPAs exhibited significantly sharper bending angles (84±17° vs. 105±13°), and a 2.4-fold greater lumen area reduction (10.17 mm² vs. 4.24 mm²) under limb flexion compared to non-calcified arteries. CONCLUSIONS: Arterial calcification significantly amplifies limb flexion-induced deformations, leading to sharper bending, greater lumen narrowing, and increased risk of intermittent flow obstruction. These findings highlight the importance of bent-leg imaging to identify high-risk arterial segments and guide targeted interventions, such as plaque modification or stent designs optimized to mitigate arterial kinking.