From the Guidelines
The most common cause of avascular necrosis (AVN) of the hip is corticosteroid use, particularly when these medications are used at high doses or for prolonged periods. According to the most recent and highest quality study 1, other significant causes include excessive alcohol consumption, traumatic hip injuries (especially femoral neck fractures or hip dislocations), and certain medical conditions like sickle cell disease and systemic lupus erythematosus. AVN occurs when blood supply to the femoral head is disrupted, leading to bone cell death and eventual collapse of the hip joint. The mechanism behind steroid-induced AVN involves fat emboli blocking small blood vessels, increased intraosseous pressure, and direct toxic effects on bone cells. For alcohol-related AVN, the mechanism involves fat accumulation in liver cells and blood vessels, along with direct toxic effects on bone-forming cells.
Some key points to consider:
- Early recognition is crucial as the condition progresses through stages, from asymptomatic bone changes to complete joint destruction.
- Risk factors often occur in combination, with the likelihood of developing AVN increasing when multiple factors are present simultaneously.
- The true prevalence of osteonecrosis is likely underestimated because many patients are asymptomatic, especially in metadiaphyseal cases.
- Recent studies have shown that MR-proven cases of femoral osteonecrosis can be retrospectively visualized on CT abdomen/pelvis with intravenous (IV) contrast performed for other clinical purposes and were originally vastly underreported 1.
- Noninvasive therapy for osteonecrosis has so far gained limited supporting data, and invasive therapies aim at preventing articular collapse and delaying/preventing the need for joint replacement.
It's worth noting that while other studies 1 provide additional information on the topic, the most recent and highest quality study 1 provides the most relevant and up-to-date information on the causes and mechanisms of AVN.
From the Research
Avascular Necrosis of the Hip
- The most common cause of avascular necrosis (AVN) of the hip is associated with several factors, including sickle cell disease and other conditions.
- Studies have shown that sickle cell disease is a significant cause of AVN, with a high prevalence of AVN in patients with this condition 2, 3, 4.
- In particular, sickle cell anemia is a common cause of AVN, with a study finding that 41% of patients with sickle cell disease had AVN of at least one hip 4.
- Other causes of AVN, such as steroid treatment or alcohol abuse, are also recognized, but are less common in certain populations 5.
- The diagnosis of AVN can be made using radiography and magnetic resonance imaging, with MRI being a useful diagnostic tool in some cases 3, 6.
- Treatment options for AVN vary, but may include conservative management or surgical intervention, depending on the severity and location of the condition 6, 5.