EFFECT OF BENDING ON CANINE AND HUMAN ARTERIAL-WALLS AND ON BLOOD-FLOW

The femoral and popliteal arteries are least affected by atherosclerosis where they cross the hip and knee joint. We evaluated possible reasons for this by studying the changes in arterial length and diameter, and the patterns of blood flow in these arteries. The changes of length due to bending of human and canine popliteal arteries were determined radiographically and changes in arterial resistance and diameter were deduced from simultaneous measurements of pressure and flow in the artery above and below the canine knee joint in different degrees of flexion. Flow patterns were assessed in the canine popliteal artery during bending by radiographic screening of a streamline. Equivalent observations were made in a mechanical model. During flexion of the knee joint, the adjacent artery shortens by as much as 20%, but the arterial diameter remains effectively unchanged. The results of the flow pattern experiments suggest that turbulent flow is generated in the distal position of an artery crossing a bending joint. We suggest that these changes may be responsible for the lack of atherosclerosis in the segments of arteries that cross joints.