All ICD10 Codes
M21Not billable, use a more specific code below

Other acquired deformities of limbs

In Other joint disorders (M20-M25), chapter 13: Diseases of the Musculoskeletal System and Connective Tissue

124 billable codes under M21: none are a CC or MCC; none map to an HCC.

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Instructional notes

Excludes1: not coded here, use a different code

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

Excludes2: not included here, code separately if applicable

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

Also applies, from Other joint disorders (M20-M25)

These notes sit on M20-M25 and apply to every code under it, including M21.

Excludes2: not included here, code separately if applicable

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Covers site and laterality, acute injury versus chronic musculoskeletal conditions, 7th characters for pathologic fractures, osteoporosis with or without current fracture, and multisystem inflammatory syndrome.

Read Section I.C.13 (page 60)

All codes under M21

M21 can't be used on a claim. Pick a billable code below; grey headings group them.

M21 MS-DRGs

As the principal diagnosis, the billable codes under M21 group to MS-DRG 564, 565, 566, 073, or 074 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.

Other codes that refer to M21

Notes on these codes point to M21.

  • M23 Excludes1: deformity of knee (M21.-)
  • M24.5 Excludes2: acquired deformities of limbs (M20-M21)
  • M25 Excludes2: acquired deformities of limb (M20-M21)
  • M95 Excludes2: acquired deformities of limbs (M20-M21)
  • Z89 Excludes1: acquired deformities of limbs (M20-M21)

About the condition

Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.

Joint Disorders

Your joints are places where two or more bones come together. Your shoulders, elbows, hips, knees, and knuckles are all joints. Your spine has joints, too.

Read more about joint disorders on MedlinePlus

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.