M21 Other acquired deformities of limbs

⚠ Non-Billable ICD-10-CM 2026
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The ICD-10-CM code for Other acquired deformities of limbs is M21 (FY2026). It is a non-billable category code — select a more specific code below for claims.

Classification

Section
M20-M25: Other joint disorders (M20-M25)
Category M21
172 codes (124 billable)
FY2026 Status
Stable since FY2024
Excludes1
Not coded here. These conditions should NOT be coded together with M21.
  • 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. These conditions are coded elsewhere but may be coded together if applicable.
  • acquired deformities of fingers or toes (M20.-)
  • coxa plana (M91.2)

Official Coding Guidelines

Osteoporosis without pathological fracture (M81)

Category M81, Osteoporosis without current pathological fracture, is for use for patients with osteoporosis who do not currently have a pathologic fracture due to the osteoporosis, even if they have had a fracture in the past. For patients with a history of osteoporosis fractures, status code Z87.310, Personal history of (healed) osteoporosis fracture, should follow the code from M81.

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.13.d.1
Osteoporosis with current pathological fracture (M80)

Category M80, Osteoporosis with current pathological fracture, is for patients who have a current pathologic fracture at the time of an encounter. The codes under M80 identify the site of the fracture. A code from category M80, not a traumatic fracture code, should be used for any patient with known osteoporosis who suffers a fracture, even if the patient had a minor fall or trauma, if that fall or trauma would not usually break a normal, healthy bone.

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.13.d.2

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

Related Codes

More Specific Codes

M21.0 Valgus deformity, not elsewhere classified M21.00 Valgus deformity, not elsewhere classified, unspecified site M21.02 Valgus deformity, not elsewhere classified, elbow M21.021 Valgus deformity, not elsewhere classified, right elbow M21.022 Valgus deformity, not elsewhere classified, left elbow M21.029 Valgus deformity, not elsewhere classified, unspecified elbow M21.05 Valgus deformity, not elsewhere classified, hip M21.051 Valgus deformity, not elsewhere classified, right hip M21.052 Valgus deformity, not elsewhere classified, left hip M21.059 Valgus deformity, not elsewhere classified, unspecified hip M21.06 Valgus deformity, not elsewhere classified, knee M21.061 Valgus deformity, not elsewhere classified, right knee M21.062 Valgus deformity, not elsewhere classified, left knee M21.069 Valgus deformity, not elsewhere classified, unspecified knee M21.07 Valgus deformity, not elsewhere classified, ankle M21.071 Valgus deformity, not elsewhere classified, right ankle M21.072 Valgus deformity, not elsewhere classified, left ankle M21.079 Valgus deformity, not elsewhere classified, unspecified ankle M21.1 Varus deformity, not elsewhere classified M21.10 Varus deformity, not elsewhere classified, unspecified site M21.12 Varus deformity, not elsewhere classified, elbow M21.121 Varus deformity, not elsewhere classified, right elbow M21.122 Varus deformity, not elsewhere classified, left elbow M21.129 Varus deformity, not elsewhere classified, unspecified elbow M21.15 Varus deformity, not elsewhere classified, hip M21.151 Varus deformity, not elsewhere classified, right hip M21.152 Varus deformity, not elsewhere classified, left hip M21.159 Varus deformity, not elsewhere classified, unspecified hip M21.16 Varus deformity, not elsewhere classified, knee M21.161 Varus deformity, not elsewhere classified, right knee

Related Codes in M21

M21.0 Valgus deformity, not elsewhere classified M21.00 Valgus deformity, not elsewhere classified, unspecified site M21.02 Valgus deformity, not elsewhere classified, elbow M21.021 Valgus deformity, not elsewhere classified, right elbow M21.022 Valgus deformity, not elsewhere classified, left elbow M21.029 Valgus deformity, not elsewhere classified, unspecified elbow M21.05 Valgus deformity, not elsewhere classified, hip M21.051 Valgus deformity, not elsewhere classified, right hip M21.052 Valgus deformity, not elsewhere classified, left hip M21.059 Valgus deformity, not elsewhere classified, unspecified hip M21.06 Valgus deformity, not elsewhere classified, knee M21.061 Valgus deformity, not elsewhere classified, right knee M21.062 Valgus deformity, not elsewhere classified, left knee M21.069 Valgus deformity, not elsewhere classified, unspecified knee M21.07 Valgus deformity, not elsewhere classified, ankle M21.071 Valgus deformity, not elsewhere classified, right ankle M21.072 Valgus deformity, not elsewhere classified, left ankle M21.079 Valgus deformity, not elsewhere classified, unspecified ankle M21.1 Varus deformity, not elsewhere classified M21.10 Varus deformity, not elsewhere classified, unspecified site
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Reviewed by Prajwal Shrestha, CPC, CRC
Certified Professional Coder (CPC) and Certified Risk Adjustment Coder (CRC) · AAPC Member ID 01997614 · About · Editorial policy · Content last reviewed: 2025-10-01

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