2026 ICD-10-CM Diagnosis Code M84.373SStress fracture, unspecified ankle, sequela

ICD-10-CM Codes›M00–M99›M80-M85›M84

ICD-10-CM M84.373S
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M84.373S is a billable ICD-10-CM diagnosis code for stress fracture, unspecified ankle, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 559 through 561. Coders also document this condition as stress fracture of ankle. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pathological, stress and atypical fractures, sequela.

Code Identity

ICD-10-CM Code
M84.373S
Billable Status
Yes — Valid for Submission
Code Describes
Stress fracture, unspecified ankle, sequela
Short Description
Stress fracture, unspecified ankle, sequela
Same as the full description in the CMS dataset.
Parent Code
M84.373
Stress fracture, unspecified ankle

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM80-M85Disorders of bone density and structure
CategoryM84Disorder of continuity of bone
This CodeM84.373SStress fracture, unspecified ankle, sequela

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Stress fracture of ankle

Clinical ClassificationClinical

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

CCSR MUS020
Pathological, stress and atypical fractures, sequela
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Ankle Injuries and Disorders

Your ankle bone and the ends of your two lower leg bones make up the ankle joint. Your ligaments, which connect bones to one another, stabilize and support it. Your muscles and tendons move it.

Read the full article at MedlinePlus

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

Convert M84.373S to ICD-9-CMHistory

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

ICD-9-CM
905.4 Late effect leg fx
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 M84.373SOverview

Is M84.373S (Stress fracture, unspecified ankle) a billable code?

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

What does the 7th character S in M84.373S mean?

The final character S makes this a sequela code: it reports a lingering problem that remains after the stress fracture, unspecified ankle itself has resolved, not the original event.

What MS-DRG does M84.373S group to?

When stress fracture, unspecified ankle, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 559, 560, 561, with relative weights from 0.8039 to 1.8649 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M84.373S?

Under the General Equivalence Mappings, stress fracture, unspecified ankle, sequela converts to ICD-9-CM 905.4 (late effect leg fx). 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.