2026 ICD-10-CM Diagnosis Code M89.279Other disorders of bone development and growth, unspecified ankle and foot

ICD-10-CM Codes›M00–M99›M86-M90›M89

ICD-10-CM M89.279
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M89.279 is a billable ICD-10-CM diagnosis code for other disorders of bone development and growth, 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 564 through 566. Coders also document this condition as small epiphysis of phalanx of fifth toe. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified bone disease and musculoskeletal deformities.

Code Identity

ICD-10-CM Code
M89.279
Billable Status
Yes — Valid for Submission
Code Describes
Other disorders of bone development and growth, unspecified ankle and foot
Short Description
Oth disorders of bone development and growth, unsp ank/ft
Parent Code
M89.27
Other disorders of bone development and growth, ankle and foot

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM86-M90Other osteopathies
CategoryM89Other disorders of bone
This CodeM89.279Other disorders of bone development and growth, unspecified ankle and foot

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Small epiphysis of phalanx of fifth toe
  • Small epiphysis of phalanx of fourth toe
  • Small epiphysis of phalanx of great toe
  • Small epiphysis of phalanx of second toe
  • Small epiphysis of phalanx of third toe
  • Small epiphysis of phalanx of toe

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 Diseases

Your bones help you move, give you shape and support your body. They are living tissues that rebuild constantly throughout your life. During childhood and your teens, your body adds new bone faster than it removes old bone. After about age 20, you can lose bone faster than you make bone.

Read the full article at MedlinePlus

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

Convert M89.279 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 M89.279Overview

Is M89.279 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other disorders of bone development and growth, unspecified ankle and foot on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M89.279 group to?

When other disorders of bone development and growth, unspecified 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 M89.279?

Under the General Equivalence Mappings, other disorders of bone development and growth, unspecified 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] 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.