2026 ICD-10-CM Diagnosis Code M85.9Disorder of bone density and structure, unspecified

ICD-10-CM Codes›M00–M99›M80-M85›M85

ICD-10-CM M85.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M85.9 is a billable ICD-10-CM diagnosis code for disorder of bone density and structure, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 564 through 566. Coders also document this condition as dysosteosclerosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified bone disease and musculoskeletal deformities.

Code Identity

ICD-10-CM Code
M85.9
Billable Status
Yes — Valid for Submission
Code Describes
Disorder of bone density and structure, unspecified
Short Description
Disorder of bone density and structure, unspecified
Same as the full description in the CMS dataset.
Parent Code
M85
Other disorders of bone density and structure

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM80-M85Disorders of bone density and structure
CategoryM85Other disorders of bone density and structure
This CodeM85.9Disorder of bone density and structure, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Dysosteosclerosis
  • SAPHO syndrome

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.

    • Disorder(of)
      • bone
        • density and structure

Clinical ClassificationClinical

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

CCSR MUS028
Other specified bone disease and musculoskeletal deformities
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Bone Density

Your bones are made of living tissue. To keep them strong, your body breaks down old bone and replaces it with new bone. But when more bone is broken down than replaced, you lose bone density, also called bone mass. Bone density is a measure of the amount of calcium and other minerals in bone. Bones containing more minerals are denser.

The full article covers:

  • What is bone density?
  • What can make you lose bone density?
  • Is there a test to measure your bone health?
  • How can I keep my bones strong?

Read the full article at MedlinePlus

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

Convert M85.9 to ICD-9-CMHistory

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

ICD-9-CM
733.90 Bone & cartilage dis NOS
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 M85.9Overview

Is M85.9 (Other disorders of bone density and structure) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report disorder of bone density and structure, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M85.9 group to?

When disorder of bone density and structure, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 564, 565, 566, with relative weights from 0.7493 to 1.5436 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M85.9?

Under the General Equivalence Mappings, disorder of bone density and structure, unspecified converts to ICD-9-CM 733.90 (bone & cartilage dis NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.