M18Header code — not billable
Osteoarthritis of first carpometacarpal joint
- Chapter
- 13. Diseases of the musculoskeletal system and connective tissue
- Category
- M18
- Effective date
- October 1, 2026
Related codes in category M18
M18.0Bilateral primary osteoarth of first carpometacarp jointsYesM18.1Unilateral primary osteoarth of first carpometacarp jointM18.10Unil prim osteoarth of first carpometacarp joint, unsp handYesM18.11Unil primary osteoarth of first carpometacarp joint, r handYesM18.12Unil primary osteoarth of first carpometacarp joint, l handYesM18.2Bi post-trauma osteoarth of first carpometacarp jointsYesM18.3Unil post-trauma osteoarth of first carpometacarp jointM18.30Unil post-trauma osteoarth of 1st carpometacarp jt,unsp handYesM18.31Unil post-trauma osteoarth of 1st carpometacarp jt, r handYesM18.32Unil post-trauma osteoarth of 1st carpometacarp jt, l handYesM18.4Oth bi secondary osteoarth of first carpometacarp jointsYesM18.5Oth unil secondary osteoarth of first carpometacarp joint
Frequently asked questions
What is ICD-10 code M18?
M18 is an ICD-10-CM diagnosis code for Osteoarthritis of first carpometacarpal joint.
Is M18 a billable code?
No. M18 is a category/header code, not billable on its own — use one of its more specific child codes instead.
What ICD-10-CM chapter is M18 in?
M18 falls under Chapter 13: Diseases of the musculoskeletal system and connective tissue.
When did M18 become effective?
M18 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to M18?
M18 belongs to category M18, which includes 12 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.