M18.1
ICD-10Non-billable categoryUnilateral primary osteoarth of first carpometacarp joint
Official ICD-10-CM descriptor (FY2026)
Unilateral primary osteoarthritis of first carpometacarpal joint
M18.1 is a category heading, not a billable code. CMS does not accept it on a claim; report one of the more specific codes beneath it.
Inclusion terms
- Primary osteoarthritis of first carpometacarpal joint NOS
ICD-10-CM FY2026 defines 3 codes beneath M18.1. See the ICD-10-CM index for what this site publishes.
Related codes in M18
- M18.0Bilateral primary osteoarth of first carpometacarp joints
- M18.2Bi post-trauma osteoarth of first carpometacarp joints
- M18.3Unil post-trauma osteoarth of first carpometacarp jointcategory
- M18.4Oth bi secondary osteoarth of first carpometacarp joints
- M18.5Oth unil secondary osteoarth of first carpometacarp jointcategory
- M18.9Osteoarthritis of first carpometacarpal joint, unspecified
Where this code sits
- Parent code
- M18
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ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.