ICD-10-CM 2027
ICD-10 code for primary osteoarthritis
From the official ICD-10-CM alphabetic index entry “Osteoarthritis › primary”. Page updated September 29, 2026.
About coding primary osteoarthritis
The ICD-10-CM code for primary osteoarthritis is M19.91 (Primary osteoarthritis, unspecified site). The official index lists 14 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on M19.91.
Within M19.9, choose M19.91 (Primary osteoarthritis, unspecified site) only when documentation doesn't support a more specific option: unspecified osteoarthritis, unspecified site (M19.90), post-traumatic osteoarthritis, unspecified site (M19.92) and secondary osteoarthritis, unspecified site (M19.93).
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.
More specific primary osteoarthritis codes (official index)
- ankle M19.07 — Primary osteoarthritis ankle and foot
- elbow M19.02 — Primary osteoarthritis, elbow
- foot joint M19.07 — Primary osteoarthritis ankle and foot
- hand joint M19.04 — Primary osteoarthritis, hand
- first carpometacarpal joint M18.1 — Unilateral primary osteoarthritis of first carpometacarpal joint
- bilateral M18.0 — Bilateral primary osteoarthritis of first carpometacarpal joints
- hip M16.1 — Unilateral primary osteoarthritis of hip
- bilateral M16.0 — Bilateral primary osteoarthritis of hip
- knee M17.1 — Unilateral primary osteoarthritis of knee
- bilateral M17.0 — Bilateral primary osteoarthritis of knee
- multiple sites M15.9 — Polyosteoarthritis, unspecified
- shoulder M19.01 — Primary osteoarthritis, shoulder
- specified site NEC M19.09 — Primary osteoarthritis, other specified site
- spine
- wrist M19.03 — Primary osteoarthritis, wrist
Common questions about primary osteoarthritis ICD-10 codes
What is the ICD-10 code for primary osteoarthritis?
- M19.91 — Primary osteoarthritis, unspecified site. More specific codes apply when the documentation supports them: M19.07, M19.02, M19.07, M19.04 and others below.
What is the ICD-10 code for ankle primary osteoarthritis?
- M19.07 — Primary osteoarthritis ankle and foot (header code; choose a more specific subcode).
What is the ICD-10 code for elbow primary osteoarthritis?
- M19.02 — Primary osteoarthritis, elbow (header code; choose a more specific subcode).
What is the ICD-10 code for foot joint primary osteoarthritis?
- M19.07 — Primary osteoarthritis ankle and foot (header code; choose a more specific subcode).
What is the ICD-10 code for hand joint primary osteoarthritis?
- M19.04 — Primary osteoarthritis, hand (header code; choose a more specific subcode).
What is the ICD-10 code for hip primary osteoarthritis?
- M16.1 — Unilateral primary osteoarthritis of hip (header code; choose a more specific subcode).
What is the ICD-10 code for knee primary osteoarthritis?
- M17.1 — Unilateral primary osteoarthritis of knee (header code; choose a more specific subcode).
Is M19.91 billable?
- Yes. M19.91 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can M19.91 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict M19.91 as a principal diagnosis.
Is M19.91 a CC or MCC?
- No. M19.91 is neither a CC nor an MCC under MS-DRG v44.0.