Idiopathic aseptic necrosis of left foot

This code signifies the spontaneous death of bone tissue in the left foot 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 joint destruction.

Apply this code when documentation clearly indicates idiopathic avascular necrosis affecting the bones of the left foot. Supporting clinical notes should rule out secondary causes like steroid use, alcoholism, or specific medical conditions. This diagnosis is often confirmed by imaging studies such as MRI.

• Ensure laterality is precisely documented (left foot).
• Distinguish idiopathic avascular necrosis from avascular necrosis due to known causes, which would be coded with a more specific M87 subcategory.
• Code any associated pain or functional impairment separately, if applicable.