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Crescent sign

Today, Crescent sign is a topic that generates great interest and debate in society. Since its emergence, it has captured the attention of experts and the general public, who seek to understand and analyze it from different perspectives. Its impact covers various aspects, from the economy to culture, and its influence extends globally. With the passage of time, Crescent sign has become a highly relevant phenomenon, giving rise to conflicting opinions and deep reflections. In this article, we will explore this relevant topic in detail, examining its implications and consequences in different areas.

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Not to be confused with the air crescent sign.
A radiograph of a left hip joint, which reveals a thin, curvilinear lucent line parallel to the cortical margin of the femoral head, in a patient with avascular necrosis.

In radiology, the crescent sign is a finding on conventional radiographs that is associated with avascular necrosis.[1][2][3] It usually occurs later in the disease, in stage III of the four-stage Ficat classification system.[1] It appears as a curved subchondral radiolucent line that is often found on the proximal femoral or humeral head.[1] Usually, this sign indicates a high likelihood of collapse of the affected bone.[1] The crescent sign may be best seen in an abducted (frog-legged) position.[1][4]

The crescent sign is caused by the necrotic and repair processes that occur during avascular necrosis.[1][2] Osteosclerosis occurs at a margin where new bone is placed over dead trabeculae.[1] When the trabeculae experience stress leading to microfractures and collapse, the crescent sign appears.[1]

The crescent sign may be seen with other bone diseases, such as shear fractures.[1]

References

  1. ^ a b c d e f g h i Pappas, J. N. (2000). "The musculoskeletal crescent sign". Radiology. 217 (1): 213–214. doi:10.1148/radiology.217.1.r00oc22213. PMID 11012446.
  2. ^ a b Kenzora, J. E.; Glimcher, M. J. (1985). "Pathogenesis of idiopathic osteonecrosis: The ubiquitous crescent sign". The Orthopedic Clinics of North America. 16 (4): 681–696. doi:10.1016/S0030-5898(20)30435-1. PMID 4058896.
  3. ^ Norman, A.; Bullough, P. (1963). "The Radiolucent Crescent Line--An Early Diagnostic Sign of Avascular Necrosis of the Femoral Head". Bulletin of the Hospital for Joint Diseases. 24: 99–104. PMID 14048829.
  4. ^ "Rheumatology Image Bank: Avascular Necrosis, Crescent Sign: Ficat Stage III, Hip". Retrieved 26 June 2012.
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