In vivo deformation of the human abdominal aorta and common iliac arteries with hip and knee flexion: implications for the design of stent-grafts.

PURPOSE: To quantify in vivo deformations of the abdominal aorta and common iliac arteries (CIAs) caused by musculoskeletal motion.
METHODS: Seven healthy subjects (age 34+/-11 years, range 24-50) were imaged in the supine and fetal positions (hip flexion angle 134.0 degrees +/-9.7 degrees ) using contrast-enhanced magnetic resonance angiography. Longitudinal strain, twisting, and curvature change of the infrarenal aorta and CIAs were computed. The angle between the left and right CIAs and translation of the arteries were also computed.
RESULTS: Maximal hip flexion induced shortening (5.2%+/-4.6%), twisting (0.45+/-0.27 degrees /mm), and curvature changes (0.015+/-0.007 mm(-1)) of the CIAs. The angle between the CIAs increased by 17.6 degrees +/-8.6 degrees . The iliac arteries moved predominantly in the superior direction relative to the aortic bifurcation, which would induce compression and bending, thus increasing curvature and angle between the CIAs. The abdominal aorta also exhibited shortening (2.9%+/-2.1%) and twisting (0.07+/-0.05 degrees /mm) deformation associated with the hip flexion.
CONCLUSION: Although this study was limited to a few healthy young adults, musculoskeletal motion, specifically hip flexion, caused significant in vivo morphological changes (shortening, twisting, and bending) of the arteries. Predominant superior translation of the CIAs was observed, which suggests that preclinical testing of cyclic superior-inferior translational motion may aid in predicting stent-graft fractures. In turn, stent-graft design could be improved, decreasing overall stent-graft-related complications.