2026 ICD-10-CM Diagnosis Code M11.079Hydroxyapatite deposition disease, unspecified ankle and foot

ICD-10-CM Codes›M00–M99›M05-M14›M11

ICD-10-CM M11.079
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M11.079 is a billable ICD-10-CM diagnosis code for hydroxyapatite deposition disease, unspecified ankle and foot. 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 hydroxyapatite deposition disease of joint of ankle. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Crystal arthropathies (excluding gout).

Code Identity

ICD-10-CM Code
M11.079
Billable Status
Yes — Valid for Submission
Code Describes
Hydroxyapatite deposition disease, unspecified ankle and foot
Short Description
Hydroxyapatite deposition disease, unsp ankle and foot
Parent Code
M11.07
Hydroxyapatite deposition disease, ankle and foot

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM05-M14Inflammatory polyarthropathies
CategoryM11Other crystal arthropathies
This CodeM11.079Hydroxyapatite deposition disease, unspecified ankle and foot

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Hydroxyapatite deposition disease of joint of ankle
  • Hydroxyapatite deposition disease of joint of foot

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

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 M11.079 to ICD-9-CMHistory

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

ICD-9-CM
712.87 Cryst arthrop NEC-ankle
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 M11.079Overview

Is M11.079 (Hydroxyapatite deposition disease, ankle and foot) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report hydroxyapatite deposition disease, unspecified ankle and foot on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M11.079 group to?

When hydroxyapatite deposition disease, unspecified ankle and foot 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 M11.079?

Under the General Equivalence Mappings, hydroxyapatite deposition disease, unspecified ankle and foot converts to ICD-9-CM 712.87 (cryst arthrop NEC-ankle). 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.