Is M18 a billable ICD-10-CM code?

No. M18 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does M18 sit in the tabular list?

Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Osteoarthritis (M15-M19).

M18

M18 — Osteoarthritis of first carpometacarpal joint

Non-billable headerICD-10-CM

M18 is a non-billable header ICD-10-CM code for osteoarthritis of first carpometacarpal joint. It cannot be billed on its own: choose one of the more specific child codes below.

Other codes that can never be billed with M18

These codes carry an Excludes1 note pointing at M18. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading M18 alone.

M12.5Traumatic arthropathy

Risk adjustment

M18 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code to one of these instead M18

7 child codes. Green means billable.

Questions about M18

Is M18 a billable ICD-10-CM code?: No. M18 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does M18 sit in the tabular list?: Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Osteoarthritis (M15-M19).