| M18.0 | Bilateral primary osteoarthritis of first carpometacarpal joints | BILLABLE CODE |
| M18.1 | Unilateral primary osteoarthritis of first carpometacarpal joint | NON-BILLABLE CODE |
| M18.10 | Unilateral primary osteoarthritis of first carpometacarpal joint, unspecified hand | BILLABLE CODE |
| M18.11 | Unilateral primary osteoarthritis of first carpometacarpal joint, right hand | BILLABLE CODE |
| M18.12 | Unilateral primary osteoarthritis of first carpometacarpal joint, left hand | BILLABLE CODE |
| M18.2 | Bilateral post-traumatic osteoarthritis of first carpometacarpal joints | BILLABLE CODE |
| M18.3 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint | NON-BILLABLE CODE |
| M18.30 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, unspecified hand | BILLABLE CODE |
| M18.31 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, right hand | BILLABLE CODE |
| M18.32 | Unilateral post-traumatic osteoarthritis of first carpometacarpal joint, left hand | BILLABLE CODE |
| M18.4 | Other bilateral secondary osteoarthritis of first carpometacarpal joints | BILLABLE CODE |
| M18.5 | Other unilateral secondary osteoarthritis of first carpometacarpal joint | NON-BILLABLE CODE |
| M18.50 | Other unilateral secondary osteoarthritis of first carpometacarpal joint, unspecified hand | BILLABLE CODE |
| M18.51 | Other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand | BILLABLE CODE |
| M18.52 | Other unilateral secondary osteoarthritis of first carpometacarpal joint, left hand | BILLABLE CODE |
| M18.9 | Osteoarthritis of first carpometacarpal joint, unspecified | BILLABLE CODE |
