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How does osteonecrosis develop when bone tissue loses its blood supply?
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bone disease
Defect of tibia, caused by septic osteomyelitis in childhood, with compensatory thickening of the fibula (right). Normal bones are shown at left.
Osteonecrosis occurs when bone tissue is deprived of its arterial blood supply for more than a few hours, leading to the death of bone cells. This interruption can be triggered by physical trauma—such as fractures or dislocations—as well as blood clots, gas bubbles, metabolic disease, or the invasion of foreign tissue.12
Once circulation ceases, the affected bone cells die and the marrow cavity fills with debris. The subsequent progression depends on the type of bone involved:2
- Cortical bone: Because it has a poorer blood supply, dead cortical bone can cause mechanical irritation and hinder healing.1
- Cancellous bone: In the epiphyses, the necrotic area is typically invaded by blood vessels from adjacent healthy bone. A repair process follows, where dead bone is resorbed and replaced by new bone.12
If this rebuilding process weakens the bone structure, it may collapse under mechanical stress, damaging the joint cartilage and potentially leading to osteoarthritis. Early treatment often focuses on preventing weight-bearing to protect the joint.1