Non-Billable / Non-Specific Code
ICD-10-CM M18.1 is the diagnosis code for Unilateral primary osteoarthritis of first carpometacarpal joint. This code falls under the section "Osteoarthritis" within Chapter 13 — Diseases of the musculoskeletal system and connective tissue (M00-M99). It is a non-billable/non-specific ICD-10-CM code that should not be used for reimbursement. A more specific sub-code is required for billing. Medical coders and healthcare providers use this code to document and classify diagnoses in electronic health records, insurance claims, and clinical databases.
Understanding where M18.1 sits in the ICD-10-CM classification helps ensure proper coding:
No, M18.1 is a non-billable/non-specific code. You should use a more specific sub-code for billing and reimbursement.
M18.1 is the ICD-10-CM diagnosis code for "Unilateral primary osteoarthritis of first carpometacarpal joint". It is used by healthcare providers to classify and document this condition in medical records and insurance claims.
The parent code of M18.1 is M18 ("Osteoarthritis of first carpometacarpal joint"). M18.1 provides a more specific classification within this category.
M18.1 is located in Section M15-M19 — "Osteoarthritis" within Chapter 13 of the ICD-10-CM Tabular List.
M18.1 has 3 sub-code(s) that provide more specific detail: M18.10, M18.11, M18.12.
Use M18.1 when the patients documented diagnosis matches "Unilateral primary osteoarthritis of first carpometacarpal joint" and the clinical documentation supports this level of specificity. Always verify with the latest ICD-10-CM guidelines and payer requirements.
The ICD-10-CM code for Unilateral primary osteoarthritis of first carpometacarpal joint is M18.1.
No, M18.1 is non-billable. Use a more specific sub-code for primary diagnosis billing.
M18.1 is in Chapter 13 of the ICD-10-CM Tabular List.
Yes, M18.1 is a valid ICD-10-CM code for the 2026 fiscal year, subject to official CMS updates.