Spontaneous osteonecrosis of the knee

Spontaneous osteonecrosis of the knee (SONK) is a condition characterized by the sudden onset of knee pain due to the death of bone tissue in the knee joint. This condition primarily affects the medial femoral condyle and is most commonly seen in older adults.

Pathophysiology

The exact cause of spontaneous osteonecrosis of the knee is not well understood. It is believed to result from a disruption in the blood supply to the bone, leading to ischemia and subsequent bone tissue death. Factors such as minor trauma, steroid use, and vascular disease may contribute to the development of SONK.

Clinical Presentation

Patients with SONK typically present with sudden onset of knee pain, often localized to the medial aspect of the knee. The pain may be exacerbated by weight-bearing activities and relieved by rest. Swelling and limited range of motion may also be observed.

Diagnosis

The diagnosis of SONK is primarily based on clinical evaluation and imaging studies. Magnetic resonance imaging (MRI) is the most sensitive modality for detecting early changes in the bone. X-rays may show subchondral radiolucency and flattening of the medial femoral condyle in advanced cases.

Treatment

The treatment of SONK depends on the stage of the disease and the severity of symptoms. Conservative management includes rest, activity modification, and nonsteroidal anti-inflammatory drugs (NSAIDs). In more severe cases, surgical options such as core decompression, osteotomy, or knee replacement may be considered.

Prognosis

The prognosis of SONK varies. Early diagnosis and appropriate management can lead to a favorable outcome, while delayed treatment may result in progressive joint degeneration and the need for surgical intervention.

See Also

• Osteonecrosis
• Knee pain
• Avascular necrosis
• Orthopedic surgery