IS Case 260: Avascular necrosis (AVN)
Imaging Sciences uRMC 2009
Publication Date: 2009-06-26
History
Patient is a 46-year-old male presenting with left-sided shoulder pain, worse with abduction. He has a history of avascular necrosis (AVN) of the hip.
Findings
A pattern of mixed subchondral sclerosis and lucencies, with mild flattening of the humeral head.
Diagnosis
Avascular necrosis (AVN)
Discussion
Avascular necrosis is the cellular death of bone tissue. It occurs when the bone is deprived of sufficient oxygen by interruption of the arterial blood supply. This can occur by numerous mechanisms including fracture, dislocation, mechanical stress, pregnancy, pancreatitis and radiation exposure to name a few. In the US, the two most common causes of AVN are steroid use and Sickle cell disease.
Initial radiographs may be completely normal; the earliest radiographic sign on plain film is a radiolucent crescent in the region of necrosis (crescent sign), which can be seen approximately 4-6 weeks after injury. In later stages, radiographs will demonstrate both lucencies, signifying the structural collapse of subchondral matrix, and sclerosis, which is due to a combination of new bone deposition and bone compression. Eventually, radiographs will demonstrate flattening of the articular head. MRI and nuclear medicine studies can also be done to diagnose this entity.
In some cases, the disease is self-limiting and no treatment other than analgesia is needed. However, in other instances, joint replacement is necessary.
References
- Greenspan A. Orthopedic Imaging: A Practical Approach, 4th ed. Philadelphia: Lippincott Williams. & Wilkins, 2004: 75-78.
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