 Cortical bone is well vascularized by the surrounding soft tissues thus less susceptible to ischaemic damage.Cancellous bone, with its mesh like structure and spaces filled with marrow tissue is more susceptible to damage by bone infarcts, leading to hypoxia and premature cell apoptosis.The mean life-span of osteocytes has been estimated to be 15 years in cancellous bone, and 25 years in cortical bone.