Geometric anatomy of the aortic--common iliac bifurcation.

Increased haemodynamic forces in the arterial wall may be among the factors responsible for atherogenesis and for determining the severity of the pathological process at a particular site. The present work was designed to help explain apparent asymmetries in the distribution of atheroma at the aorto-iliac bifurcation. A technique was devised for the quantitative evaluation of the geometric anatomy of this region. Measurements were made on 12 female and 14 male cadavers. In all cases there was an asymmetrical left lateral orientation of the abdominal aorta which resulted in a longer right common iliac artery, smaller left common iliac take-off angle and larger left radius of curvature at the aortic-common illiac bifurcation. These differences may explain, through variations in the local haemodynamics, the predilection of the disease for the left iliac artery, particularly in males with their relatively narrow pelvis. Knowledge of both the exact and the average numerical values associated with the local geometry are essential for a detailed haemodynamic study of the effect of these variations on atherogenesis.