ICD-10-CM 2027 diagnosis code
M89.421Other hypertrophic osteoarthropathy, right upper arm
M89.421 is a valid, billable ICD-10-CM code for other hypertrophic osteoarthropathy, right upper arm. 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 M89.421
M89.421 is the ICD-10-CM diagnosis code for other hypertrophic osteoarthropathy, right upper arm. It belongs to category M89 (other disorders of bone), block M86-M90 (other osteopathies) 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 M89.42 (other hypertrophic osteoarthropathy, upper arm), M89.421 is specifically for other hypertrophic osteoarthropathy, right upper arm. Related codes cover left upper arm (M89.422) and unspecified upper arm (M89.429).
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 553 (Bone Diseases and Arthropathies with MCC, relative weight 1.2494) and DRG 554 (Bone Diseases and Arthropathies without MCC, relative weight 0.8331), 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 731.2 (hypertrophic pulmonary osteoarthropathy).
Notes that apply from higher levels
Instructions written at a parent level also apply to M89.421.
Broader instructions also apply from M86-M90 Other osteopathies 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 →- 731.2Hypertrophic pulmonary osteoarthropathyapproximate
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 M89.421
Is M89.421 billable?
- Yes. M89.421 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can M89.421 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict M89.421 as a principal diagnosis.
Is M89.421 a CC or MCC?
- No. M89.421 is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does M89.421 group to?
- M89.421 is used in the MS-DRG v44.0 logic for MS-DRG 553 (Bone Diseases and Arthropathies with MCC) and MS-DRG 554 (Bone Diseases and Arthropathies without 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 M89.421?
- The CMS General Equivalence Mappings map M89.421 to ICD-9-CM 731.2.