ICD-10-CM 2027 diagnosis code
M20.021Boutonniere deformity of right finger(s)
M20.021 is a valid, billable ICD-10-CM code for boutonniere deformity of right finger(s). It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
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 M20.021
M20.021 is the ICD-10-CM diagnosis code for Boutonniere deformity of right finger(s). It belongs to category M20 (acquired deformities of fingers and toes), block M20-M25 (other joint disorders) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within M20.02 (Boutonniere deformity), M20.021 is specifically for Boutonniere deformity of right finger(s). Related codes cover of left finger(s) (M20.022) and of unspecified finger(s) (M20.029).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 564 (Other Musculoskeletal System and Connective Tissue Diagnoses with MCC, relative weight 1.4908), DRG 565 (Other Musculoskeletal System and Connective Tissue Diagnoses with CC, relative weight 0.9783) and DRG 566 (Other Musculoskeletal System and Connective Tissue Diagnoses without CC/MCC, relative weight 0.7378), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 736.21 (Boutonniere deformity).
Notes that apply from higher levels
Instructions written at a parent level also apply to M20.021.
› From M20.0 Deformity of finger(s)
Broader instructions also apply from M20-M25 Other joint disorders and Chapter 13: Diseases of the musculoskeletal system and connective tissue.
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 08 · Diseases and Disorders of the Musculoskeletal System and Connective Tissue
ICD-9-CM equivalent
Converter →- 736.21Boutonniere deformityapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about M20.021
Is M20.021 billable?
- Yes. M20.021 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can M20.021 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict M20.021 as a principal diagnosis.
Is M20.021 a CC or MCC?
- No. M20.021 is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does M20.021 group to?
- M20.021 is used in the MS-DRG v44.0 logic for MS-DRG 564 (Other Musculoskeletal System and Connective Tissue Diagnoses with MCC), MS-DRG 565 (Other Musculoskeletal System and Connective Tissue Diagnoses with CC) and MS-DRG 566 (Other Musculoskeletal System and Connective Tissue Diagnoses without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for M20.021?
- The CMS General Equivalence Mappings map M20.021 to ICD-9-CM 736.21.