The pattern of distribution of blood flow in dog limb bones measured using microspheres.

The distribution of blood flow to segments of the leg bones of anaesthetised dogs was studied using radioactive microspheres injected into the heart or the tibial nutrient artery. Following central injection, repeated measurements after an interval showed no change of pattern of distribution. The effects of ligation of the tibial nutrient artery during this interval suggested that 30% of the blood flow to the tibia is normally via this vessel, which predominantly supplies the diaphysis. This deduction differed from that derived from the injection of microspheres during perfusion through a tibial nutrient artery cannula, when half the flow reached the epiphyses. This proportion decreased and the flow to the diaphyseal marrow increased after alternate periods of perfusion and ischaemia, demonstrating the labile nature of bone blood flow distribution.