2026 ICD-10-CM Diagnosis Code S56.409SUnspecified injury of extensor muscle, fascia and tendon of unspecified finger at forearm level, sequela

ICD-10-CM Codes›S00–T88›S50-S59›S56

ICD-10-CM S56.409S
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S56.409S is a billable ICD-10-CM diagnosis code for unspecified injury of extensor muscle, fascia and tendon of unspecified finger at forearm level, 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 913 through 914. The code is exempt from POA reporting. Coders also document this condition as injury of extensor muscle at forearm level. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury, sequela.

Code Identity

ICD-10-CM Code
S56.409S
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified injury of extensor muscle, fascia and tendon of unspecified finger at forearm level, sequela
Short Description
Unsp inj extn musc/fasc/tend unsp finger at forarm lv, sqla
Parent Code
S56.409
Unspecified injury of extensor muscle, fascia and tendon of unspecified finger at forearm level

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS50-S59Injuries to the elbow and forearm
CategoryS56Injury of muscle, fascia and tendon at forearm level
This CodeS56.409SUnspecified injury of extensor muscle, fascia and tendon of unspecified finger at forearm level, sequela

Present on Admission (POA)Billing

S56.409S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Injury of extensor muscle at forearm level
  • Injury of extensor muscle of finger at forearm level
  • Injury of fascia of extensor muscle at forearm level
  • Injury of fascia of extensor muscle of finger at forearm level
  • Injury of fascia of forearm
  • Injury of tendon of extensor muscle at forearm level
  • Injury of tendon of extensor muscle of finger at forearm level

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Injury of muscle, fascia and tendon at forearm level (S56). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

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

CCSR INJ073
Injury, sequela
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Arm Injuries and Disorders

Of the 206 bones in your body, three of them are in your arm: the humerus, radius, and ulna. Your arms are also made up of muscles, joints, tendons, and other connective tissue. Injuries to any of these parts of the arm can occur during sports, a fall, or an accident.

Read the full article at MedlinePlus

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

Convert S56.409S to ICD-9-CMHistory

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

ICD-9-CM
908.9 Late effect injury 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 S56.409SOverview

Is S56.409S a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified injury of extensor muscle, fascia and tendon of unspecified finger at forearm level, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character S in S56.409S mean?

The final character S makes this a sequela code: it reports a lingering problem that remains after the unspecified injury of extensor muscle, fascia and tendon of unspecified finger at forearm level itself has resolved, not the original event.

What MS-DRG does S56.409S group to?

When unspecified injury of extensor muscle, fascia and tendon of unspecified finger at forearm level, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 913, 914, with relative weights from 0.8855 to 1.6346 depending on complications. Higher weights mean higher Medicare reimbursement.

Is S56.409S exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for unspecified injury of extensor muscle, fascia and tendon of unspecified finger at forearm level, sequela on inpatient claims.

What is the ICD-9 equivalent of S56.409S?

Under the General Equivalence Mappings, unspecified injury of extensor muscle, fascia and tendon of unspecified finger at forearm level, sequela converts to ICD-9-CM 908.9 (late effect injury 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.