A patient asks the nurse why his hip fracture (head of the femur) bone has died (osteonecrosis). The nurse responds based on which of the following pathophysiological principles?
A)
All fractured bones interrupt blood supply and thereby results in death of the bone no matter where it is located.
B)
Most of the time when the head of the femur breaks, the entire neck region is disconnected to the rest of the bone so the blood vessels are severed.
C)
Since the head of the femur has only limited collateral circulation, interruption in the blood flow from the fracture causes necrosis and irreversible damage.
D)
When the femur head breaks, it dislocates and crushes the surrounding area causing the blood vessels to be occluded.
Ans:
C
Feedback:
Bone has a rich blood supply that varies from site to site. The flow in the medullary portion of bone originates in nutrient vessels from an interconnecting plexus that supplies the marrow, trabecular bone, and endosteal half of the cortex. Some bony sites, such as the head of the femur, have only limited collateral circulation, so that interruption of the flow, such as with a hip fracture, can cause necrosis of a substantial portion of medullary and cortical bone and irreversible damage. Not all fractures interrupt blood supply to the bone. It is not common for the entire head of the femur to break off leaving the area with no blood supply.
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