Effect of circumferential bands on cortical vascularity and viability.

Wire cerclage devices do not restrict cortical vascularity; however, bands, because they are flat and wide, have been implicated as the cause of fracture nonunion by disruption of cortical vascularity. This experiment evaluated the effect of cerclage bands on the cortical vascularity of bones that had not been fractured. Stainless-steel bands of four sizes (2.5, 5.0, 7.5, and 10.0 mm wide) and nylon bands of five sizes (2.5, 3.6, 4.8, 7.6, and 9.0 mm wide) were applied 1 cm apart to both femoral diaphyses of four mature dogs. In two additional dogs, 18-gauge cerclage wires were applied 5 mm apart on one femur and nylon bands were applied immediately adjacent to one another on the other femur to cover 3 cm of the length of each femoral diaphysis. These six dogs were euthanatized and perfused 7 days postoperatively and specimens were studied by microangiography and correlated histology. Two additional dogs were studied 4 and 15 weeks after application of nylon and metal bands. There was no evidence of complete cortical devascularization under any size or type of cerclage appliance at any time interval. Numerous examples of vessels traversing the cortex directly beneath all the cerclage appliances were observed. Cerclage devices, even when flat and wide, do not restrict cortical vascularity when applied to intact bones.