Stress fracture, left ulna, subs for fx w nonunion

This code signifies a stress fracture of the left ulna that has failed to heal properly, indicating a nonunion. It specifically applies to a patient who is receiving active treatment for this nonunion, beyond the initial fracture care.

Use this code for patients presenting with a documented stress fracture of the left ulna where previous treatment has not resulted in bone healing, and they are currently undergoing treatment for this nonunion. Documentation should clearly state "nonunion" and specify the left ulna as the affected site, with the encounter being for ongoing management.

• Requires an additional code for any associated external cause of the stress fracture, if known.
• Distinguish from initial encounters (A) or subsequent encounters for routine healing (D).
• Ensure documentation explicitly states "nonunion" and the specific bone (ulna) and laterality (left).