Path fx in oth disease, unsp ankle, subs for fx w nonunion

This code signifies a pathological fracture of an unspecified ankle bone that has failed to heal properly (nonunion) and is being treated in a subsequent encounter. This type of fracture occurs due to an underlying disease weakening the bone, rather than from trauma.

Apply this code for patients presenting with an ankle nonunion resulting from a pathological fracture, where the underlying disease is not specified. Documentation should clearly indicate a pathological fracture, nonunion, and that this is not the initial treatment phase.

• Always sequence the underlying disease causing the pathological fracture first, if known.
• Ensure documentation specifies "nonunion" and "pathological fracture" to differentiate from malunion or traumatic fractures.
• Verify the encounter type (initial, subsequent, sequela) to select the correct 7th character.