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ICD-10-CM 2027 diagnosis code

M21.7Unequal limb length (acquired)

Not billable — use a more specific code

M21.7 is a header code, so it can't be reported by itself. Choose one of the 5 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About M21.7

M21.7 is the ICD-10-CM diagnosis code for unequal limb length (acquired). It belongs to category M21 (other acquired deformities of limbs), block M20-M25 (other joint disorders) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is a header code, so it can't be reported by itself; one of its 5 subcodes must be used instead.

Within M21 (other acquired deformities of limbs), M21.7 is specifically for unequal limb length (acquired). Related codes cover valgus deformity, not elsewhere classified (M21.0), varus deformity, not elsewhere classified (M21.1), flexion deformity (M21.2), wrist or foot drop (acquired) (M21.3), Flat foot [pes planus] (acquired) (M21.4), acquired clawhand, clubhand, clawfoot and clubfoot (M21.5), other acquired deformities of foot (M21.6), other specified acquired deformities of limbs (M21.8) and 1 more.

To report this condition, pick the subcode that matches the documentation: M21.70 (unspecified site), M21.72 (humerus), M21.73 (ulna and radius), M21.75 (femur) and M21.76 (tibia and fibula).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under M21.7

Coding notes

Note
  • The site used should correspond to the shorter limb

Notes that apply from higher levels

Instructions written at a parent level also apply to M21.7.

› From M21 Other acquired deformities of limbs
Excludes1
  • acquired absence of limb (Z89.-)
  • congenital absence of limbs (Q71-Q73)
  • congenital deformities and malformations of limbs (Q65-Q66, Q68-Q74)
Excludes2
  • acquired deformities of fingers or toes (M20.-)
  • coxa plana (M91.2)

Broader instructions also apply from M20-M25 Other joint disorders and Chapter 13: Diseases of the musculoskeletal system and connective tissue.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about M21.7

Is M21.7 billable?

No. M21.7 is a header code. Report one of its more specific subcodes instead.