Osteonecrosis -Avascular Necrosis
So what actually is Bone death anyway.
It’s mostly of the break down in the vascular system (blood supply)that runs through the bone.
Although bone is not an actively growing tissue in adults, it does need a constant blood supply to stay alive. In fact, the supply of blood to long bones is profuse and derived from a number of sources that are explained with detail in the lines below.
Blood supply of bones
This artery enters the shaft through the nutrient foramen and runs obliquely through the cortex. In the medullary cavity this artery divides into ascending and descending branches. Each one of these two branches divides into parallel channels that head towards the respective end of the bone. At the place of metaphyses in case of adult bones these branches anastomose with epiphyseal, metaphyseal and periosteal arteries. The nutrient artery in this way nourishes the whole medullary cavity and inner 2/3 of the cortex as well as metaphyses.
Periosteal arteries are the arteries of periosteum being especially numerous beneath the muscular and ligamentous attachment. Beneath the periosteum they divide into branches and thereby entering the Volkmann’s canals to supply the outer one third (1/3) portion of the cortex. Remember that the inner 2/3 of the cortex was supplied by the nutrient artery discussed above.
These are the arteries of epiphyses and are derived from the peri-articular vascular arcades found on the non-articular bony surfaces. This area also has numerous foramina out of which only few are the entrance points of these arteries while the remaining are the venous exits.
These arteries are derived from the neighboring systemic vessels. These arteries directly go into the metaphyses and reinforce the metaphyseal branches of the primary nutrient artery.
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