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M18.1

Non-billable

Unilateral primary osteoarthritis of first carpometacarpal joint

M18.1 is the ICD-10-CM code for Unilateral primary osteoarthritis of first carpometacarpal joint. It is a non-billable category code — use a more specific child code such as M18.10 for billing.

Status
Header (non-billable)
Chapter
M00-M99
Parent
M18
Subcodes
3
Edition
FY2026

M00-M99 Diseases of the musculoskeletal system and connective tissue

Includes

  • •Primary osteoarthritis of first carpometacarpal joint NOS

Frequently asked questions

What is ICD-10 code M18.1?
M18.1 is the ICD-10-CM code for "Unilateral primary osteoarthritis of first carpometacarpal joint". It falls under M00-M99 Diseases of the musculoskeletal system and connective tissue.
Is M18.1 a billable code?
No — M18.1 is a non-billable header code. Use a more specific child code (such as M18.10) for billing.
What are the subcodes of M18.1?
M18.1 has 3 more specific child codes, including M18.10, M18.11, M18.12.

Source: CMS ICD-10-CM FY2026. For informational purposes only — not medical advice. See our medical disclaimer.

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