Orthopedic Coding Alert

Question: A patient who had an arthroscopy on his left knee decided less than 90 days later that he wanted a total knee replacement (TKR). Because the TKR occurred within the global period for the arthroscopy, which modifier should we use when coding the TKR?

Montana Subscriber

Answer: In this case, append modifier -58 (staged or related procedure or service by the same physician during the postoperative period) to 27447. The TKR is related to the first procedure, as both were performed for the same diagnosis. The TKR was more extensive than the first surgery (the arthroscopy).

Some coders may be tempted to use modifiers -78 (return to the operating room for a related procedure during the postoperative period) or -79 (unrelated procedure or service by the same physician during the postoperative period), but these are not the most accurate. The -78 implies a complication of the original surgery.

In this case, the patient elected to have the TKR rather than wait and see the longer-term results of the arthroscopy. The -79 implies that the subsequent surgery was unrelated to the first, which is not accurate in this case either.