What is a significant risk factor for osteonecrosis in patients with Cushing syndrome?

Long-term corticosteroid use is a significant risk factor for osteonecrosis in patients with Cushing syndrome. Cushing syndrome is characterized by an excess of cortisol, which can be caused by endogenous overproduction or exogenous administration of corticosteroids. Chronic exposure to corticosteroids leads to various metabolic and structural changes within bones, including the disruption of the bone repair mechanism and compromise of blood supply.

This diminished blood flow to the bone can result in avascular necrosis, where bone tissue dies due to a lack of oxygen and nutrients. The specific mechanism often involves increased intraosseous pressure, which can lead to bone marrow edema and subsequent death of bone cells. Hence, the association between long-term corticosteroid use and increased risk of osteonecrosis is well-established within the context of Cushing syndrome, tying directly to the effects of prolonged corticosteroid exposure on bone health.

While other factors like hypertension, high cholesterol, and diabetes can affect overall health and have some association with the risk of osteoporotic fractures, they are not as directly linked to osteonecrosis as long-term corticosteroid use.