Flat foot [pes planus] (acquired), unspecified foot

This code represents an acquired flattening of the medial longitudinal arch of the foot, where the entire sole of the foot comes into contact with the ground. This condition, also known as pes planus, is not present at birth but develops over time due to various factors. It is characterized by the absence of further specification regarding which foot is affected.

Use this code when documentation indicates an acquired flat foot without specifying laterality (left or right). This is appropriate for initial evaluations or when the physician's documentation does not differentiate between the feet. Supporting documentation would include a diagnosis of "acquired flat foot," "pes planus, acquired," or similar, without laterality.

• Do not use this code if the documentation specifies congenital flat foot; use codes from category Q66.5.
• Avoid this code if laterality (left or right foot) is documented; instead, select the more specific codes M21.41 (right) or M21.42 (left).
• Ensure the documentation clearly states "acquired" to differentiate from congenital forms.