Study of the Impact of the Location of a Perforator in the Perfusion of a Perforator Flap: The Concept of "Angle of Perfusion".

Background Perforator flaps remain challenging in their design, especially as free flaps. We used a cadaveric model to help refine the design of perforator flaps by studying their vascular features. We define the angle of perfusion of a perforator as a tool to achieve safer flap designs. Methods A total of 83 flaps were designed from 20 fresh cadaveric anterolateral thigh flaps. The most dominant perforator larger than 0.5 mm was used as the reference point on the midline of the flap, and the tip of the flap was set at 5 cm (n = 10), 2 cm (n = 5), or 10 cm (n = 5) from this perforator. The perforator was injected with contrast agent, and the flap was scanned with computed tomography (CT) angiography. The vascular territory of the injected perforator was drawn twice by two different investigators. Perfused volumes were then obtained through a computerized algorithm on the CT workstation. Flaps were then flushed with heparinized saline and cut at decreasing angles (120, 90, 60, and 45 degrees) and rescanned with contrast for each perfusion angle. The perfused volumes were calculated for each angle. Results Volume and percentage of perfusion were significantly decreased with decreasing angles of perfusion, regardless of perforator location (2 cm, p = 0.002; 5 cm, p = 0.02; 10 cm, p < 0.001). Conclusions Acute angles of perfusion were associated with fewer incorporated linking vessels and lower flap perfusion. This phenomenon was less apparent in centrally located perforators. Perfusion angle and perforator location influence flap vascularity in a cadaveric model.