The propellar-type flap design is increasingly used in reconstructive surgery for various regions of the body. To date, determinants of perforator patency when subjected to twisting have not been elucidated. We propose a simulation model to study parameters affecting perforator patency under such conditions.

The effect of the following parameters on the pedicle patency was determined; 1) increasing angle of twist, 2) vessel stiffness, 3) vessel length, 4) diameter, 5) intra-luminal pressure, and 6) the presence or absence of blood flow during twisting.

Simulation results were reported in effective stress and strain. The vein was more prone to occlusion because of its weaker wall and lower intra-luminal pressure. We identified 4 factors that affected perforator patency: angle of twist, intra-luminal blood pressure and perforator diameter and length. There was no significant difference whether twisting was performed prior to or after restoration of blood flow (p > 0.05). Therefore, to optimize condition for maintaining perforator patency, the angle of twist should be kept < 180°, peri-operative blood pressure should be kept stable (avoiding periods of hypotension), and the selected perforator should be approximately 1mm in diameter and > 30 mm in length.