Other hypertrophic osteoarthropathy, unspecified forearm

This code signifies a non-specific form of hypertrophic osteoarthropathy affecting an unspecified forearm. This condition involves abnormal bone and joint changes, often characterized by periostosis (new bone formation on the surface of existing bone) and clubbing of the digits, but without a definitive underlying cause identified or specified to a particular type.

Use this code when documentation indicates hypertrophic osteoarthropathy in the forearm, but the specific type (e.g., primary, secondary) is not documented, or the underlying etiology is unknown. This code is appropriate when the laterality of the forearm (right or left) is also not specified in the medical record.

• Ensure documentation clearly states "hypertrophic osteoarthropathy" and specifies the forearm as the affected site.
• Avoid using this code if a more specific type of hypertrophic osteoarthropathy (e.g., primary, secondary to a known condition) is documented.
• Query the provider for laterality if not specified, as more specific codes exist for right (M89.431) and left (M89.432) forearms.