Osteonecrosis due to previous trauma of unspecified ulna

This code signifies the death of bone tissue in an unspecified ulna, specifically attributed to a prior traumatic injury. This condition, also known as avascular necrosis, results from an interruption of blood supply to the bone, leading to bone collapse and potential joint destruction.

Apply this code when documentation clearly indicates osteonecrosis of the ulna and explicitly links its etiology to a previous traumatic event. This diagnosis is typically supported by imaging studies (e.g., MRI, X-ray) showing bone necrosis, coupled with a patient history of trauma to the affected arm.

• Ensure the documentation specifies "previous trauma" as the cause of osteonecrosis; otherwise, a different etiology code may be more appropriate.
• Verify laterality if available; this code is for an unspecified ulna. If left or right is documented, a more specific code should be used.
• Consider sequencing this code after any acute traumatic injury codes if the trauma is still being treated concurrently.