Acute effects of intramedullary reaming on bone blood flow in rats.

We examined the acute effects of increasing degree of intramedullary reaming on bone blood flow in 27 male Wistar rats by use of the microsphere method. A marginal reduction in total bone and cortical bone blood flow was seen when the femoral canal was reamed to a diameter smaller than the medullary cavity (1.5 mm). Reaming equal to the antero-posterior diameter (1.8 mm) halved total bone flow and reduced cortical blood flow by one third. Reaming equal to the transverse diameter (2.1 mm) reduced total bone flow to one third and cortical bone flow by one third. Intramedullary reaming of the tibia to 1.5 mm reduced total blood flow about 50 percent whereas cortical flow in the proximal half was unchanged. We conclude that modest intramedullary reaming has little effect on total and cortical blood flows, whereas reaming which involves destruction of the endosteal cortex reduces both total bone and cortical blood flows.