Path fx in oth disease, l fibula, subs for fx w nonunion

This code signifies a fracture of the left fibula that occurred due to an underlying disease process, not from trauma. The fracture is currently in a state of nonunion, meaning it has failed to heal completely, and the patient is receiving ongoing treatment for this unhealed fracture.

Apply this code when documentation indicates a left fibula fracture caused by a pathological condition (e.g., osteoporosis, tumor, metabolic bone disease) that has not healed and the patient is seen for follow-up care. This code is appropriate for subsequent encounters after initial treatment, where nonunion is explicitly documented.

• Requires documentation of both the pathological nature of the fracture and the nonunion status.
• Always sequence this code after the underlying disease causing the pathological fracture.
• Distinguish from malunion (M84.4-) and routine follow-up for a healing fracture (M84.5-).