Acquired deformities of fingers and toes (M20) ICD-10-CM
The M20 code range covers acquired deformities of fingers and toes with 47 ICD-10-CM diagnosis codes. 33 of them are billable and valid for claim submission in fiscal year 2027, and the category headers group them but cannot themselves be billed.
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Codes in the M20 Range 47 codes · 33 billable
- M20 Acquired deformities of fingers and toesNon-billable
- M20.0 Deformity of finger(s)Non-billable
- M20.00 Unspecified deformity of finger(s)Non-billable
- M20.001 Unspecified deformity of right finger(s)
- M20.002 Unspecified deformity of left finger(s)
- M20.009 Unspecified deformity of unspecified finger(s)
- M20.01 Mallet fingerNon-billable
- M20.011 Mallet finger of right finger(s)
- M20.012 Mallet finger of left finger(s)
- M20.019 Mallet finger of unspecified finger(s)
- M20.02 Boutonniere deformityNon-billable
- M20.021 Boutonniere deformity of right finger(s)
- M20.022 Boutonniere deformity of left finger(s)
- M20.029 Boutonniere deformity of unspecified finger(s)
- M20.03 Swan-neck deformityNon-billable
- M20.031 Swan-neck deformity of right finger(s)
- M20.032 Swan-neck deformity of left finger(s)
- M20.039 Swan-neck deformity of unspecified finger(s)
- M20.09 Other deformity of finger(s)Non-billable
- M20.091 Other deformity of right finger(s)
- M20.092 Other deformity of left finger(s)
- M20.099 Other deformity of finger(s), unspecified finger(s)
- M20.1 Hallux valgus (acquired)Non-billable
- M20.10 Hallux valgus (acquired), unspecified foot
- M20.11 Hallux valgus (acquired), right foot
- M20.12 Hallux valgus (acquired), left foot
- M20.2 Hallux rigidusNon-billable
- M20.20 Hallux rigidus, unspecified foot
- M20.21 Hallux rigidus, right foot
- M20.22 Hallux rigidus, left foot
- M20.3 Hallux varus (acquired)Non-billable
- M20.30 Hallux varus (acquired), unspecified foot
- M20.31 Hallux varus (acquired), right foot
- M20.32 Hallux varus (acquired), left foot
- M20.4 Other hammer toe(s) (acquired)Non-billable
- M20.40 Other hammer toe(s) (acquired), unspecified foot
- M20.41 Other hammer toe(s) (acquired), right foot
- M20.42 Other hammer toe(s) (acquired), left foot
- M20.5 Other deformities of toe(s) (acquired)Non-billable
- M20.5X Other deformities of toe(s) (acquired)Non-billable
- M20.5X1 Other deformities of toe(s) (acquired), right foot
- M20.5X2 Other deformities of toe(s) (acquired), left foot
- M20.5X9 Other deformities of toe(s) (acquired), unspecified foot
- M20.6 Acquired deformities of toe(s), unspecifiedNon-billable
- M20.60 Acquired deformities of toe(s), unspecified, unspecified foot
- M20.61 Acquired deformities of toe(s), unspecified, right foot
- M20.62 Acquired deformities of toe(s), unspecified, left foot
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the M20 range.
Hallux Rigidus
A condition caused by degenerative arthritis (see OSTEOARTHRITIS) of the METATARSOPHALANGEAL JOINT of the great toe and characterized by pain and limited dorsiflexion, but relatively unrestricted plantar flexion.
Hallux Valgus
Lateral displacement of the great toe (HALLUX), producing deformity of the first METATARSOPHALANGEAL JOINT with callous, bursa, or BUNION formation over the bony prominence.
Hallux Varus
Displacement of the great toe (HALLUX) towards the midline or away from the other TOES. It can be congenital or acquired.
About the M20 Code Range
These deformities are acquired changes in the shape of fingers or toes. The category separates finger deformities from toe deformities.
M20.0 groups finger deformities by named pattern, including mallet finger, boutonniere deformity, and swan-neck deformity. Its subdivisions also distinguish right, left, and unspecified fingers.
The toe groups distinguish hallux valgus, hallux rigidus, hallux varus, other hammer toes, and other or unspecified acquired deformities. Their subdivisions identify the right, left, or unspecified foot.
Questions About This Page
How many billable codes are in the M20 range?
Of the 47 codes in this range, 33 are billable and valid for claim submission from October 1, 2026 through September 30, 2027. Category header codes group them but cannot be reported on claims.
What does the M20 range classify?
The range classifies acquired deformities of fingers and toes. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
