Acquired medial deviation of the left great toe at the first metatarsophalangeal joint, resulting from a non-congenital cause such as prior surgery, trauma, or inflammatory arthritis.

Documentation tips

What should appear in the chart to support M20.32.

Source · Editorial brief grounded in 4 cited references ↓

• Document laterality explicitly as 'left foot' or 'left great toe' — do not rely on the coder to infer side from imaging or procedure notes.
• Specify that the deformity is acquired, not congenital, and identify the precipitating cause (e.g., prior hallux valgus surgery, trauma, inflammatory arthritis) to support medical necessity.
• Record clinical findings that confirm medial deviation of the hallux: inter-metatarsal angle, range of motion at the first MTP joint, and any associated soft-tissue contracture.
• If the deformity follows prior surgery, document the operative history and link this encounter's diagnosis to that prior procedure so a complication code can be evaluated.
• Weight-bearing radiograph findings (degree of varus angulation at the first MTP joint) should be noted; they support specificity and justify surgical planning if applicable.

Related CPT procedures

Procedure codes commonly billed with M20.32. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

Common coding pitfalls

The recurring mistakes coders make with M20.32 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

• Coding M20.30 (unspecified foot) when the operative or imaging report clearly identifies the left foot — always assign the laterality-specific code when documentation supports it.
• Confusing hallux varus (medial deviation, coded M20.32) with hallux valgus (lateral deviation, M20.12) — these are opposite deformities and are not interchangeable.
• Applying a congenital toe deformity code (Q66.-, Q68-Q70) when the deformity is documented as acquired — the Excludes1 note at M20 prohibits dual coding for the same condition.
• Omitting an external cause code when the etiology is a prior surgical procedure or trauma, missing an opportunity to fully describe the clinical picture.
• Reporting only one laterality code when bilateral acquired hallux varus is present — both M20.31 and M20.32 must be reported separately.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

Sibling codes

Other billable codes under M20.3 (laterality / anatomic variants).