Osteonecrosis in diseases classd elswhr, unsp ankle and foot

This code describes the death of bone tissue in an unspecified ankle or foot, resulting from an underlying medical condition. This osteonecrosis is a secondary manifestation of another disease process, rather than a primary bone disorder.

Assign this code when documentation specifies osteonecrosis of an unspecified ankle or foot, and explicitly links it to an underlying systemic disease (e.g., lupus, sickle cell anemia, steroid use). The medical record must clearly indicate the osteonecrosis is a complication or manifestation of another classified condition.

• Always sequence the underlying systemic disease code first, as this code is for a manifestation classified elsewhere.
• Avoid using this code if the osteonecrosis is idiopathic or due to trauma; instead, refer to codes in the M87 category.
• Ensure the documentation specifies "unspecified ankle and foot" to justify the 9th character; otherwise, a more specific site code should be used.