Avascular necrosis (AVN), also called osteonecrosis or bone infarction, is death of bone tissue due to interruption of the blood supply. Early on, there may be no symptoms. Gradually joint pain may develop which may limit the ability to move. Complications may include collapse of the bone or nearby joint surface.Risk factors include bone fractures, joint dislocations, alcoholism, and the use of high-dose steroids. The condition may also occur without any clear reason. The most commonly affected bone is the femur. Other relatively common sites include the upper arm bone, knee, shoulder, and ankle. Diagnosis is typically by medical imaging such as X-ray, CT scan, or MRI. Rarely biopsy may be used.Treatments may include medication, not walking on the affected leg, stretching, and surgery. Most of the time surgery is eventually required and may include core decompression, osteotomy, bone grafts, or joint replacement. About 15,000 cases occur per year in the United States. People 30 to 50 years old are most commonly affected. Males are more commonly affected than females. Signs and symptoms
In many cases, there is pain and discomfort in a joint which increases over time. While it can affect any bone, about half of cases show multiple sites of damage.Avascular necrosis most commonly affects the ends of long bones such as the femur. Other common sites include the humerus, knees, shoulders, ankles and the jaw. Causes
The main risk factors are bone fractures, joint dislocations, alcoholism, and the use of high-dose steroids. Other risk factors include radiation therapy, chemotherapy, and organ transplantation.
A tuberculoma is a clinical manifestation of tuberculosis which conglomerates tubercles into a firm lump, and so can mimic cancer tumors of many types in medical imaging studies. Since these are evolutions of primary complex, the tuberculomas may contain within caseum or calcifications. With the passage of time Mycobacterium tuberculosis can transform into crystals of calcium. These can affect any organ such as the brain, intestine, ovaries, breast, lungs, esophagus, liver, pancreas, bones, and many others. As the histologic and clinical indications, as well as tumor markers such as the CA-125, are similar, it is often difficult to differentiate tuberculoma from cancer. For these reasons, tuberculosis should always be considered in the differential diagnosis of cancer.Tuberculoma is commonly treated through the HRZE drug combination (Isoniazid, Rifampin, Pyrazinamide, Ethambutol) followed by maintenance therapy. == References ==