2026 ICD-10-CM Diagnosis Code M18.0Bilateral primary osteoarthritis of first carpometacarpal joints

ICD-10-CM Codes›M00–M99›M15-M19›M18

ICD-10-CM M18.0
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M18.0 is a billable ICD-10-CM diagnosis code for bilateral primary osteoarthritis of first carpometacarpal joints. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 553 through 554. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Osteoarthritis.

Code Identity

ICD-10-CM Code
M18.0
Billable Status
Yes — Valid for Submission
Code Describes
Bilateral primary osteoarthritis of first carpometacarpal joints
Short Description
Bilateral primary osteoarth of first carpometacarp joints
Parent Code
M18
Osteoarthritis of first carpometacarpal joint

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM15-M19Osteoarthritis
CategoryM18Osteoarthritis of first carpometacarpal joint
This CodeM18.0Bilateral primary osteoarthritis of first carpometacarpal joints

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Arthritis of bilateral first carpometacarpal joints
  • Arthritis of first carpometacarpal joint of left hand
  • Arthritis of first carpometacarpal joint of right hand
  • Bilateral osteoarthritis of first carpometacarpal joint
  • Bilateral wrist osteoarthritis
  • Degenerative joint disease of thumb
  • Inflammation of thumb joint
  • Osteoarthritis of first carpometacarpal joint of left hand
  • Osteoarthritis of first carpometacarpal joint of right hand
  • Osteoarthritis of joint of bilateral hands
  • Osteoarthritis of joint of left hand
  • Osteoarthritis of joint of left wrist
  • Osteoarthritis of joint of right hand
  • Osteoarthritis of joint of right wrist
  • Osteoarthrosis of the carpometacarpal joint of the thumb
  • Primary arthrosis of first carpometacarpal joints, bilateral

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Osteoarthritis
      • primary
        • hand joint
          • first carpometacarpal joint
            • bilateral

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS006
Osteoarthritis
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Osteoarthritis

Osteoarthritis, sometimes called OA, is a type of arthritis that only affects the joints, usually in the hands, knees, hips, neck, and lower back. It's the most common type of arthritis.

The full article covers:

  • What is osteoarthritis?
  • What are the symptoms of osteoarthritis?
  • What causes osteoarthritis?
  • Who is more likely to develop osteoarthritis?
  • How is osteoarthritis diagnosed?
  • What are the treatments for osteoarthritis?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M18.0 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
715.14 Loc prim osteoarth-hand
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M18.0Overview

Is M18.0 (Osteoarthritis of first carpometacarpal joint) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report bilateral primary osteoarthritis of first carpometacarpal joints on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M18.0 group to?

When bilateral primary osteoarthritis of first carpometacarpal joints is the principal diagnosis on an inpatient stay, it groups to MS-DRG 553, 554, with relative weights from 0.8301 to 1.2963 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M18.0?

Under the General Equivalence Mappings, bilateral primary osteoarthritis of first carpometacarpal joints converts to ICD-9-CM 715.14 (loc prim osteoarth-hand). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.