Osteonecrosis due to drugs of unspecified ulna

This code signifies the death of bone tissue in an unspecified ulna, specifically caused by the use of certain medications. This condition, also known as avascular necrosis, results from an interruption of blood supply to the bone, leading to its collapse and potential joint destruction.

Apply this code when documentation clearly indicates osteonecrosis of the ulna and explicitly links its etiology to drug use, but the specific ulna (left or right) is not specified. Supporting documentation would include physician notes detailing the diagnosis, imaging reports confirming osteonecrosis, and a medication history implicating a drug as the causative agent.

• Ensure the documentation specifies "unspecified ulna" and drug-induced etiology; otherwise, a more specific code for laterality or cause may be appropriate.
• Do not use this code if the osteonecrosis is due to trauma, radiation, or other non-drug causes.
• Always sequence this code after the underlying drug-induced condition, if applicable, or after the drug adverse effect code (T36-T50 with 5th or 6th character 5).