M18: Osteoarthritis of first carpometacarpal joint
Codes under M18 (Osteoarthritis of first carpometacarpal joint). A ✓ marks a billable (fully specified) code; category codes without a ✓ are not billable on their own.
| Code | Description | Billable |
|---|---|---|
| M18.0 | Bilateral primary osteoarthritis of first carpometacarpal joints | ✓ |
| M18.0 | Bilateral primary osteoarthritis of first carpometacarpal joints | ✓ |
| M18.1 | Unilateral primary osteoarthritis of first carpometacarpal joint | — |
| M18.1 | Unilateral primary osteoarthritis of first carpometacarpal joint | — |
| M18.2 | Bilateral post-traumatic osteoarthritis of first carpometacarpal joints | ✓ |
| M18.2 | Bilateral post-traumatic osteoarthritis of first carpometacarpal joints | ✓ |
| M18.3 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint | — |
| M18.3 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint | — |
| M18.4 | Other bilateral secondary osteoarthritis of first carpometacarpal joints | ✓ |
| M18.4 | Other bilateral secondary osteoarthritis of first carpometacarpal joints | ✓ |
| M18.5 | Other unilateral secondary osteoarthritis of first carpometacarpal joint | — |
| M18.5 | Other unilateral secondary osteoarthritis of first carpometacarpal joint | — |
| M18.9 | Osteoarthritis of first carpometacarpal joint, unspecified | ✓ |
| M18.9 | Osteoarthritis of first carpometacarpal joint, unspecified | ✓ |
| M18.10 | Unilateral primary osteoarthritis of first carpometacarpal joint, unspecified hand | ✓ |
| M18.10 | Unilateral primary osteoarthritis of first carpometacarpal joint, unspecified hand | ✓ |
| M18.11 | Unilateral primary osteoarthritis of first carpometacarpal joint, right hand | ✓ |
| M18.11 | Unilateral primary osteoarthritis of first carpometacarpal joint, right hand | ✓ |
| M18.12 | Unilateral primary osteoarthritis of first carpometacarpal joint, left hand | ✓ |
| M18.12 | Unilateral primary osteoarthritis of first carpometacarpal joint, left hand | ✓ |
| M18.30 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, unspecified hand | ✓ |
| M18.30 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, unspecified hand | ✓ |
| M18.31 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, right hand | ✓ |
| M18.31 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, right hand | ✓ |
| M18.32 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, left hand | ✓ |
| M18.32 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, left hand | ✓ |
| M18.50 | Other unilateral secondary osteoarthritis of first carpometacarpal joint, unspecified hand | ✓ |
| M18.50 | Other unilateral secondary osteoarthritis of first carpometacarpal joint, unspecified hand | ✓ |
| M18.51 | Other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand | ✓ |
| M18.51 | Other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand | ✓ |
| M18.52 | Other unilateral secondary osteoarthritis of first carpometacarpal joint, left hand | ✓ |
| M18.52 | Other unilateral secondary osteoarthritis of first carpometacarpal joint, left hand | ✓ |
Frequently asked questions
What is ICD-10-CM code M18?
M18 is an ICD-10-CM category covering Osteoarthritis of first carpometacarpal joint. It contains 32 more specific diagnosis codes, 26 of which are billable.
Is M18 a billable code?
No — M18 is a category header and isn't billable on its own. Code to the highest level of specificity using one of its subcodes (for example M18.0 — Bilateral primary osteoarthritis of first carpometacarpal joints). 26 of the 32 codes under M18 are billable.
What codes fall under M18?
M18 includes M18.0, M18.0, M18.1, M18.1, M18.2, plus 27 more. See the full list with descriptions and billable status above.
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Informational only, not coding or medical advice. Verify against the official ICD-10-CM (FY2026) and your payer's guidelines.
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