Idiopathic aseptic necrosis of right ankle

This code signifies the death of bone tissue in the right 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 confirms idiopathic avascular necrosis affecting the right ankle. This diagnosis is typically supported by imaging studies (e.g., MRI, X-ray) showing characteristic bone changes, along with a physician's assessment ruling out secondary causes.

• Ensure documentation specifies "idiopathic" or "aseptic" and clearly identifies the right ankle as the affected site.
• Distinguish from avascular necrosis due to trauma (e.g., S82.8XXA for fracture-related avascular necrosis) or other secondary causes, which would require different codes.
• Code any associated arthritis or joint degeneration separately if documented and clinically significant.