Osteonekroosi

Osteonekroosi, also known as avascular necrosis of bone, is a condition in which bone tissue dies due to insufficient blood supply. This loss of blood flow weakens the affected bone, can cause a subchondral fracture, and may lead to collapse of the joint surface if not treated. The femoral head (hip) is the most commonly involved site, but osteonekroosi can affect any bone, including the shoulder, knee, ankle, jaw, and wrist.

The condition can arise from traumatic injury that disrupts blood vessels, or from non-traumatic factors. Risk factors include high-dose or prolonged corticosteroid use, heavy alcohol use, sickle cell disease, decompression illness, radiation therapy, autoimmune diseases, coagulation disorders, and obesity. In some cases no clear cause is found.

Pathophysiologically, interruption of blood flow leads to death of bone cells and gradual weakening of bone structure. Over time, the weakened area may deform or collapse, particularly under joint load, which can result in secondary osteoarthritis and reduced joint function.

Diagnosis is based on clinical symptoms and imaging. Early stages may have little to no pain and may be detected by magnetic resonance imaging (MRI), which is more sensitive than X-rays. X-rays often show changes only after the disease has progressed. CT can help delineate bone detail, while laboratory tests are generally used to evaluate risk factors rather than to confirm the diagnosis.

Treatment depends on stage and location. Nonoperative measures include activity modification, pain relief, and physical therapy, with limited or protected weight-bearing as appropriate. Surgical options aim to preserve the joint or replace it, such as core decompression, bone grafts, vascularized grafts, osteotomies, or joint replacement in advanced disease. Early detection and management can delay progression and improve outcomes.