Stress fracture, left tibia, subs for fx w nonunion

This code signifies a stress fracture of the left tibia that has failed to heal properly, indicating a nonunion. The patient is receiving active treatment for this nonunion, which is a complication of the initial stress fracture.

Apply this code when documentation clearly states a left tibial stress fracture with nonunion, and the patient is currently undergoing treatment for this nonunion. This includes follow-up visits, cast changes, or surgical interventions aimed at promoting healing of the nonunion. Documentation should specify "nonunion" and the "subsequent encounter" status.

• Ensure documentation explicitly states "nonunion" and the specific bone (tibia).
• Verify the encounter type is "subsequent" for the nonunion treatment, not initial or sequela.
• Distinguish from malunion (M84.4-) or routine follow-up for a healing fracture (M84.362D).