Idiopathic aseptic necrosis of left ulna

This code signifies the spontaneous death of bone tissue in the left ulna due to a lack of blood supply, without an identifiable underlying cause such as trauma, infection, or systemic disease. This condition, also known as osteonecrosis or avascular necrosis, leads to bone collapse and joint destruction if left untreated.

Apply this code when documentation explicitly states idiopathic aseptic necrosis affecting the left ulna. This diagnosis is typically supported by imaging studies (e.g., X-ray, MRI) showing characteristic bone changes and a thorough clinical workup ruling out secondary causes of osteonecrosis.

• Ensure the laterality (left) is clearly documented.
• Distinguish from traumatic osteonecrosis, which would be coded differently.
• Verify that "idiopathic" or "aseptic" is specified; otherwise, a more general or unspecified code might be appropriate.