Crescent sign

Crescent sign is a radiological sign that is often associated with avascular necrosis of the hip. It is seen as a linear subchondral radiolucency on plain radiographs and is one of the earliest signs of avascular necrosis.

Overview

The crescent sign is a radiographic feature seen in avascular necrosis of the hip where there is a curvilinear subchondral lucency in the femoral head. This sign is typically seen in the anterolateral aspect of the femoral head. The sign is indicative of a subchondral fracture, which is a fracture that occurs beneath the cartilage of a joint.

Clinical Significance

The crescent sign is significant as it is one of the earliest signs of avascular necrosis. Avascular necrosis, also known as osteonecrosis, is a condition that occurs when there is loss of blood to the bone. This can lead to tiny breaks in the bone and the bone's eventual death.

The crescent sign is often seen in patients with risk factors for avascular necrosis such as corticosteroid use, alcoholism, sickle cell disease, and trauma. Early detection of avascular necrosis is crucial as it can help prevent further joint damage. Therefore, the identification of the crescent sign can aid in the early diagnosis and treatment of avascular necrosis.

Diagnosis

The diagnosis of avascular necrosis and the identification of the crescent sign is typically made through imaging studies. Plain radiographs of the hip are usually the first step in diagnosis. However, the crescent sign may not be visible in the early stages of the disease. In such cases, other imaging studies such as MRI or bone scan may be used.

Treatment

The treatment of avascular necrosis aims to prevent further bone loss. This can be achieved through medications, therapy, and in severe cases, surgery. The specific treatment plan will depend on the severity of the condition and the patient's overall health.

See Also

• Avascular necrosis
• Radiology
• Hip joint
• Bone scan
• MRI

References

Crescent sign Resources
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