M21.73 – Unequal limb length (acquired), ulna and radius

ICD-10-CM 2027 diagnosis code · Other joint disorders

Non-billable header

ICD-10-CM code M21.73

Code: M21.73 (claims format: M2173)
Description: Unequal limb length (acquired), ulna and radius
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 13. Diseases of the musculoskeletal system and connective tissue (M00-M99)
Block: M20-M25 Other joint disorders
Parent codes: M21 › M21.7

Billable codes under M21.73

M21.73 is a header code and cannot be used on claims. Choose the most specific code:

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

M21 – Other acquired deformities of limbs

Excludes1 (not coded here):

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):

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

M21.7 – Unequal limb length (acquired)

Notes:

The site used should correspond to the shorter limb

Block M20-M25

Excludes2 (not included here):

joints of the spine (M40-M54)

Index terms for M21.73

Entries in the ICD-10-CM alphabetic index that lead to this code:

Related codes in M21.7

Frequently asked questions

What is ICD-10 code M21.73?

M21.73 is the ICD-10-CM code for unequal limb length (acquired), ulna and radius, in the block M20-M25 (Other joint disorders).

Is M21.73 a billable code?

No. M21.73 is a header code with more specific child codes; report one of the billable codes listed above.

What category does M21.73 belong to?

It belongs to category M21 – Other acquired deformities of limbs.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.