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Why are the hip and knee especially vulnerable to damage from osteonecrosis?

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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.

The hip and knee are particularly vulnerable to osteonecrosis primarily due to the mechanical forces they endure as weight-bearing joints.1

When osteonecrosis affects the cancellous bone of the epiphyses (the ends of long bones), the body attempts to repair the area by invading it with new blood vessels and forming new bone. However, this rebuilding process can weaken the bone's structural integrity. Because the hip and knee must support significant weight, this weakened bone is prone to collapsing under mechanical stress. Once the bone structure collapses, the overlying joint cartilage becomes damaged, which frequently leads to the development of osteoarthritis.1

Because of this risk of collapse, early clinical management of osteonecrosis in these areas often focuses on preventing the joint from bearing weight to protect the bone while it heals.1