M12.5 vs M18.3
M12.5 and M18.3 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on M12.5
post-traumatic osteoarthritis of first carpometacarpal joint (M18.2-M18.3)
M12.5
Traumatic arthropathy
Not billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M05-M14
M18.3
Unilateral post-traumatic osteoarthritis of first carpometacarpal joint
Not billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M15-M19
Use when the record says
- Post-traumatic osteoarthritis of first carpometacarpal joint NOS
Indexed under
- Osteoarthritis › post-traumatic NEC › hand joint › first carpometacarpal joint
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027