M21.4
Non-billableFlat foot [pes planus] (acquired)
M21.4 is the ICD-10-CM code for Flat foot [pes planus] (acquired). It is a non-billable category code — use a more specific child code such as M21.40 for billing.
M00-M99 Diseases of the musculoskeletal system and connective tissue
What this means — in plain language
MedlinePlus · NIHEach of your feet has 26 bones, 33 joints, and more than 100 tendons, muscles, and ligaments. No wonder a lot of things can go wrong. Here are a few common problems: Bunions - hard, painful bumps on the big toe joint Corns and calluses - thickened skin from friction or pressure Plantar warts - warts on the soles of your feet Fallen arches - also called flat feet Ill-fitting shoes often cause these problems. Aging…
Read more about Foot Injuries and Disorders at MedlinePlus ↗Source: U.S. National Library of Medicine (MedlinePlus). Informational only — not medical advice.
Excludes1 — not coded here
- •congenital pes planus (Q66.5-)
Frequently asked questions
- What is ICD-10 code M21.4?
- M21.4 is the ICD-10-CM code for "Flat foot [pes planus] (acquired)". It falls under M00-M99 Diseases of the musculoskeletal system and connective tissue.
- Is M21.4 a billable code?
- No — M21.4 is a non-billable header code. Use a more specific child code (such as M21.40) for billing.
- What are the subcodes of M21.4?
- M21.4 has 3 more specific child codes, including M21.40, M21.41, M21.42.
- What is excluded from M21.4?
- Excludes1 (not coded here): congenital pes planus (Q66.5-).
Source: CMS ICD-10-CM FY2026. For informational purposes only — not medical advice. See our medical disclaimer.
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