2026 ICD-10-CM Diagnosis Code M11.9Crystal arthropathy, unspecified

ICD-10-CM Codes›M00–M99›M05-M14›M11

ICD-10-CM M11.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M11.9 is a billable ICD-10-CM diagnosis code for crystal arthropathy, unspecified. 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. Coders also document this condition as crystal arthropathy. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Crystal arthropathies (excluding gout).

Code Identity

ICD-10-CM Code
M11.9
Billable Status
Yes — Valid for Submission
Code Describes
Crystal arthropathy, unspecified
Short Description
Crystal arthropathy, unspecified
Same as the full description in the CMS dataset.
Parent Code
M11
Other crystal arthropathies

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM05-M14Inflammatory polyarthropathies
CategoryM11Other crystal arthropathies
This CodeM11.9Crystal arthropathy, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Crystal arthropathy
  • Crystal arthropathy of ankle AND/OR foot
  • Crystal arthropathy of elbow
  • Crystal arthropathy of multiple sites
  • Crystal arthropathy of pelvis

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.

    • Arthritis, arthritic(acute) (chronic) (nonpyogenic) (subacute)
      • in (due to)
        • crystals

Clinical ClassificationClinical

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

CCSR MUS034
Crystal arthropathies (excluding gout)
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Crystal Arthropathies

    joint disorders that are characterized by accumulation of microcrystals in and around the joint including in the synovial fluid. they are classified according to the chemical nature of the crystals such as calcium pyrophosphate; basic calcium phosphates; and monosodium urate (see uric acid).

Patient EducationClinical

Arthritis

If you feel pain and stiffness in your body or have trouble moving around, you might have arthritis. Any disorder that affects the joints is often called arthritis. Joints are places where two bones meet, such as your elbow or knee.

The full article covers:

  • What is arthritis?
  • What are the types of arthritis?
  • What are the symptoms of arthritis?
  • Who is more likely to get arthritis?
  • How is arthritis diagnosed?
  • What are the treatments for arthritis?

Read the full article at MedlinePlus

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

Convert M11.9 to ICD-9-CMHistory

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

ICD-9-CM
712.90 Cryst arthrop NOS-unspec
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 M11.9Overview

Is M11.9 (Other crystal arthropathies) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report crystal arthropathy, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M11.9 group to?

When crystal arthropathy, unspecified 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 M11.9?

Under the General Equivalence Mappings, crystal arthropathy, unspecified converts to ICD-9-CM 712.90 (cryst arthrop NOS-unspec). 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.