Oth fx fourth MC bone, left hand, subs for fx w nonunion

This code signifies a fracture of the fourth metacarpal bone in the left hand that has not healed properly and is being treated in a subsequent encounter. Nonunion indicates that the bone ends have failed to unite after a sufficient time period, often requiring further intervention.

Apply this code when documenting follow-up care for a patient with a previously diagnosed left fourth metacarpal fracture where imaging or clinical assessment confirms nonunion. This would include scenarios such as continued cast changes, physical therapy, or surgical planning for the nonunion.

• Always ensure documentation clearly specifies "left hand" and "fourth metacarpal."
• Confirm the encounter is "subsequent" and that "nonunion" is explicitly stated or clearly implied by the treatment plan for failed healing.
• Pair with an external cause code if the original fracture etiology is relevant and documented.