2026 ICD-10-CM Diagnosis Code M18.51Other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand

ICD-10-CM Codes›M00–M99›M15-M19›M18

ICD-10-CM M18.51
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M18.51 is a billable ICD-10-CM diagnosis code for other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand. 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
M18.51
Billable Status
Yes — Valid for Submission
Code Describes
Other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand
Short Description
Oth unil sec osteoarth of first carpometacarp joint, r hand
Parent Code
M18.5
Other unilateral secondary osteoarthritis of first carpometacarpal joint

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM15-M19Osteoarthritis
CategoryM18Osteoarthritis of first carpometacarpal joint
This CodeM18.51Other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand

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 M18.51 to ICD-9-CMHistory

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

ICD-9-CM
715.24 Loc 2nd osteoarthro-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 M18.51Overview

Is M18.51 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M18.51 group to?

When other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand 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 M18.51?

Under the General Equivalence Mappings, other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand converts to ICD-9-CM 715.24 (loc 2nd osteoarthro-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.