Small-vessel pathology and anastomosis following maxillofacial firearm wounds: an experimental study.

This experiment was designed to provide a biological basis for early reconstruction of maxillofacial defects caused by firearms using free vascularized flap transfer. The pathologic changes of small-vessel injury, injury mechanism, and the feasibility for early anastomosis of these vessels in the maxillofacial region following high-velocity missile wounds were studied. Dogs' faces were wounded by a steel sphere, weighing 0.7 g and 1.03 g, with an initial velocity of 1,300 m/s or 1,500 m/s. Angiography and high-speed x-ray photography were used to record the effect of injury to blood vessels and other tissues. The pathologic changes in the small blood vessels in the wounds were studied by light microscopy (LM) and electron microscopy (EM). Anastomosis of small vessels in the wound was performed at different times after injury. There were temporary cavity effects and small vascular injury in the wounds. The pathologic changes of the small vessels included microthrombus formation, endothelial loss, breaks in the internal elastic layer, and necrosis. Degeneration of cells was found to end 3 cm from the wound edge. Anastomosis of the vessels performed 3 days after injury provided good short-term patency. These results suggest that the operation for repairing facial defects should be performed 3 days after injury.