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	✓
M18.1	Unilateral primary osteoarthritis of first carpometacarpal joint	—
M18.2	Bilateral post-traumatic osteoarthritis of first carpometacarpal joints	✓
M18.3	Unilateral post-traumatic osteoarthritis of first carpometacarpal joint	—
M18.4	Other bilateral secondary osteoarthritis of first carpometacarpal joints	✓
M18.5	Other unilateral secondary osteoarthritis of first carpometacarpal joint	—
M18.9	Osteoarthritis of first carpometacarpal joint, unspecified	✓
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	✓
M18.30	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	✓
M18.50	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	✓

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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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