Idiopathic aseptic necrosis of right ulna

This code signifies the death of bone tissue in the right ulna due to a lack of blood supply, without an identifiable cause (idiopathic) and not caused by infection (aseptic). This condition, also known as avascular necrosis or osteonecrosis, leads to bone collapse and subsequent arthritis if untreated.

Apply this code when documentation explicitly states idiopathic aseptic necrosis affecting the right ulna. This diagnosis is typically confirmed through imaging studies such as MRI or X-ray, showing characteristic bone changes and ruling out other etiologies like trauma or infection.

• Ensure the documentation specifies "idiopathic" and "aseptic" to differentiate from other forms of osteonecrosis.
• Verify the laterality is clearly stated as "right ulna"; codes exist for other sites and unspecified laterality.
• Do not use this code if a specific cause (e.g., steroid-induced, post-traumatic) is identified; instead, code the specific type of osteonecrosis.