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M21

⚠ Non-billable (Header)

Other acquired deformities of limbs

Diseases of the musculoskeletal system and connective tissue (M00-M99)

⚠️ This is a category header code — not billable. Use a more specific child code below.

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❌ Excludes1

direct

Cannot be coded with M21

  • • acquired absence of limb (Z89.-)
  • • congenital absence of limbs (Q71-Q73)
  • • congenital deformities and malformations of limbs (Q65-Q66, Q68-Q74)

⚠️ Excludes2

direct

May be coded together if both conditions coexist

  • • acquired deformities of fingers or toes (M20.-)
  • • coxa plana (M91.2)

Child Codes (10)

M21.0Valgus deformity, not elsewhere classifiedM21.1Varus deformity, not elsewhere classifiedM21.2Flexion deformityM21.3Wrist or foot drop (acquired)M21.4Flat foot [pes planus] (acquired)M21.5Acquired clawhand, clubhand, clawfoot and clubfootM21.6Other acquired deformities of footM21.7Unequal limb length (acquired)M21.8Other specified acquired deformities of limbsM21.9Unspecified acquired deformity of limb and hand

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Code Information

CodeM21
BillableNo — Header code
CategoryDiseases of the musculoskeletal system and connective tissue (M00-M99)
Excludes13 rule(s)
Excludes22 note(s)
Child codes10

Data Source

CMS ICD-10-CM 2026 Tabular List

Updated October 1, 2025 (FY2026)