Pathological fracture, unsp humerus, subs for fx w malunion

This code signifies a fracture of an unspecified humerus that occurred due to an underlying disease process, not trauma. The patient is in a subsequent phase of care for this pathological fracture, and the bone has healed incorrectly, resulting in a malunion.

Use this code for follow-up encounters where a patient is being treated for complications of a previously sustained pathological humerus fracture that has healed in a misaligned position. Documentation should clearly state "pathological fracture," "humerus," "malunion," and indicate a subsequent encounter for the fracture.

• Ensure documentation specifies "pathological" to differentiate from traumatic fractures.
• Verify the encounter type is "subsequent" and not initial or sequela.
• Confirm the presence of malunion; if nonunion, a different code from the M84.4- category would be appropriate.