Osteoarthritis of first carpometacarpal joint (M18) ICD-10-CM
The M18 code range covers osteoarthritis of first carpometacarpal joint with 17 ICD-10-CM diagnosis codes. 13 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Codes in the M18 Range 17 codes · 13 billable
- M18 Osteoarthritis of first carpometacarpal jointNon-billable
- M18.0 Bilateral primary osteoarthritis of first carpometacarpal joints
- M18.1 Unilateral primary osteoarthritis of first carpometacarpal jointNon-billable
- M18.10 Unilateral primary osteoarthritis of first carpometacarpal joint, unspecified hand
- M18.11 Unilateral primary osteoarthritis of first carpometacarpal joint, right hand
- M18.12 Unilateral primary osteoarthritis of first carpometacarpal joint, left hand
- M18.2 Bilateral post-traumatic osteoarthritis of first carpometacarpal joints
- M18.3 Unilateral post-traumatic osteoarthritis of first carpometacarpal jointNon-billable
- M18.30 Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, unspecified hand
- M18.31 Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, right hand
- M18.32 Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, left hand
- M18.4 Other bilateral secondary osteoarthritis of first carpometacarpal joints
- M18.5 Other unilateral secondary osteoarthritis of first carpometacarpal jointNon-billable
- M18.50 Other unilateral secondary osteoarthritis of first carpometacarpal joint, unspecified hand
- M18.51 Other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand
- M18.52 Other unilateral secondary osteoarthritis of first carpometacarpal joint, left hand
- M18.9 Osteoarthritis of first carpometacarpal joint, unspecified
About the M18 Code Range
ICD-10 code M18 identifies osteoarthritis affecting the first carpometacarpal joint at the base of the thumb. These codes specify the disease’s laterality, cause (primary, post-traumatic, or secondary), and whether one or both hands are involved.
This section includes detailed codes such as M18.0 for bilateral primary osteoarthritis and M18.1 for unilateral primary cases. Common alternate terms like degenerative joint disease of thumb or osteoarthrosis of the carpometacarpal joint of the thumb correspond directly to these codes, aiding coders in accurate identification. Post-traumatic forms use codes like M18.2 (bilateral) and M18.3 (unilateral). Additionally, there are codes for other secondary osteoarthritis types (M18.4 and M18.5). The unspecified osteoarthritis of this joint is covered by M18.9. Recognizing these distinctions helps healthcare professionals document thumb joint degeneration accurately for treatment and billing.
Questions About This Page
How many billable codes are in the M18 range?
Of the 17 codes in this range, 13 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the M18 range classify?
The range classifies osteoarthritis of first carpometacarpal joint. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
