Idiopathic aseptic necrosis of left ankle

This code signifies the death of bone tissue in the left ankle joint due to a lack of blood supply, without an identifiable cause such as trauma or infection. This condition, also known as avascular necrosis or osteonecrosis, leads to bone collapse and subsequent arthritis.

Apply this code when documentation clearly indicates idiopathic avascular necrosis affecting the left ankle. Supporting clinical findings often include imaging reports (X-ray, MRI) showing bone infarction and collapse, alongside a physician's diagnosis ruling out secondary causes.

• Ensure laterality is precisely documented and coded; this code specifically refers to the left ankle.
• Distinguish idiopathic aseptic necrosis from avascular necrosis due to trauma (e.g., S82.892A for other fracture of left ankle, initial encounter for closed fracture) or other specified causes.
• Code any associated pathological fractures or secondary osteoarthritis separately, if documented.