Radial Nerve Palsy following Surgical Treatment of Nonunion.
I have given this a lot of thought, and done some research. As best I can reconstruct this scenario, the patient was treated of a fracture of the proximal humerus which proceeded to a nonunion. Your note does not indicate the fracture pattern or laterality, so I am going am going to approach this rather generically, using the defaults Closed and Displaced, "?" marks for Laterality, and using S42.2(other fracture of the proximal humerus)9(displaced)?K(closed fracture with nonunion) = S42.29?K, which would be the Preoperative Diagnosis.
After the procedure for the nonunion, an Acute Radial Nerve Palsy is identified, and is a New Problem (Initial Encounter = 7th Character A), a complication/sequela of treatment. This complication is usually an Intra-operative complication that is identified/recognized in the immediate postoperative period when the patient is alert enough to be examined after anesthesia for nerve function. In spite of what anybody wants to think, surgical treatment of a nonunion is "traumatic," to the upper arm in this case. Therefore, the Postoperative Diagnosis changes to S42.29?S, as now there is a complication/sequela. The Sequela is an Acute Traumatic Radial Nerve Palsy, S44.2?(side)XA. G56.3? is Acute Radial Nerve palsy, but not from "Trauma," so it can't be used.
The next code would have to be for an Intra-operative Complication. The most applicable is G97.81, Other Intra-operative complications of the Nervous System. M96.8 covers Intra-operative and Postoperative Complications, but only to Musculoskeletal tissues, which does not include nerves (or blood vessels for that matter). This would probably function as an External Cause Code for the nerve injury.
Therefore, I would code the Postoperative Diagnoses as S42.29?S, S44.2?XA, and G97.81.
Respectfully submitted, Alan Pechacek, M.D.