Alphabetic Index FY2027

M21.73

Unequal limb length (acquired), ulna and radius

FY2027Chapter 13: Diseases of the musculoskeletal system and connective tissue/M20–M25 Other joint disorders

Non-billable headerNot valid on its own. Use one of the more specific codes under it.

M21.73 is a non-billable ICD-10-CM code header for unequal limb length (acquired), ulna and radius. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are M21.731 Unequal limb length (acquired), right ulna; M21.732 Unequal limb length (acquired), left ulna; M21.733 Unequal limb length (acquired), right radius; M21.734 Unequal limb length (acquired), left radius and 1 more. Its coding notes include 3 Excludes1 entries and 13 Excludes2 entries.

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Inherited from M21 Other acquired deformities of limbs
  • 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. Both codes may be reported if the patient has both conditions.

Inherited from M21 Other acquired deformities of limbs
  • acquired deformities of fingers or toes (M20.-)
  • coxa plana (M91.2)
Also from chapter/block level (11 notes)
Inherited from M20–M25 Other joint disorders
Inherited from Chapter 13 Diseases of the musculoskeletal system and connective tissue
  • arthropathic psoriasis (L40.5-)
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • compartment syndrome (traumatic) (T79.A-)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Notes

Inherited from M21.7 Unequal limb length
  • The site used should correspond to the shorter limb
Also from chapter/block level (1 note)
Inherited from Chapter 13 Diseases of the musculoskeletal system and connective tissue
  • Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 2 entries

More specific codes under M21.73 5