2026 ICD-10-CM Diagnosis Code M85.171Skeletal fluorosis, right ankle and foot

ICD-10-CM Codes›M00–M99›M80-M85›M85

ICD-10-CM M85.171
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M85.171 is a billable ICD-10-CM diagnosis code for skeletal fluorosis, right 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 564 through 566. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified bone disease and musculoskeletal deformities.

Code Identity

ICD-10-CM Code
M85.171
Billable Status
Yes — Valid for Submission
Code Describes
Skeletal fluorosis, right ankle and foot
Short Description
Skeletal fluorosis, right ankle and foot
Same as the full description in the CMS dataset.
Parent Code
M85.17
Skeletal fluorosis, ankle and foot

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 CodeM85.171Skeletal fluorosis, right ankle and foot

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

Convert M85.171 to ICD-9-CMHistory

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

ICD-9-CM
733.99 Bone & cartilage dis NEC
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 M85.171Overview

Is M85.171 (Skeletal fluorosis, ankle and foot) a billable code?

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

What MS-DRG does M85.171 group to?

When skeletal fluorosis, right ankle and foot 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 M85.171?

Under the General Equivalence Mappings, skeletal fluorosis, right ankle and foot converts to ICD-9-CM 733.99 (bone & cartilage dis NEC). 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.