What are the causes of avascular necrosis of the femoral head?

Avascular necrosis of the femoral head, medically known as ischemic or aseptic necrosis of the femoral head, is a common orthopedic disease. It is mainly characterized by tissue necrosis in the femoral head (the upper end of the thigh bone) due to insufficient blood supply. Under normal circumstances, bones require adequate blood supply to maintain their structure and function. Once the blood supply is reduced or interrupted, bone cells gradually die, leading to structural damage of the bone. This is the basic pathological process of avascular necrosis of the femoral head.

1. Traumatic factors: Such as femoral neck fractures and hip dislocations. These injuries can damage the blood supply to the femoral head, thus causing its necrosis.

2. Alcohol abuse: Long-term heavy drinking can lead to alcohol poisoning, affect vascular endothelial function, cause thickening of the vessel walls, narrowing of the lumen, and slowed blood flow, eventually resulting in ischemic necrosis of the femoral head.

3. Decompression sickness: Common among divers and others in similar professions, this occurs when moving rapidly from a high-pressure to a low-pressure environment, causing gas bubbles to form in the bloodstream, leading to vascular embolism and subsequent necrosis of the femoral head.

4. Autoimmune diseases: Conditions such as systemic lupus erythematosus and rheumatoid arthritis may compromise the blood supply to the femoral head, thereby increasing the risk of necrosis.

In the early stages, avascular necrosis of the femoral head may present no obvious symptoms. However, as the condition progresses, patients may experience hip pain and difficulty walking.