2026 ICD-10-CM Diagnosis Code S46.399DOther injury of muscle, fascia and tendon of triceps, unspecified arm, subsequent encounter

ICD-10-CM Codes›S00–T88›S40-S49›S46

ICD-10-CM S46.399D
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S46.399D is a billable ICD-10-CM diagnosis code for other injury of muscle, fascia and tendon of triceps, unspecified arm, subsequent encounter. The 7th character D marks it as a subsequent encounter code, used during routine care in the healing or recovery phase. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 949 through 950. The code is exempt from POA reporting. Coders also document this condition as complete division, triceps tendon. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury to nerves, muscles and tendons, subsequent encounter.

Code Identity

ICD-10-CM Code
S46.399D
Billable Status
Yes — Valid for Submission
Code Describes
Other injury of muscle, fascia and tendon of triceps, unspecified arm, subsequent encounter
Short Description
Inj muscle, fascia and tendon of triceps, unsp arm, subs
Parent Code
S46.399
Other injury of muscle, fascia and tendon of triceps, unspecified arm

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS40-S49Injuries to the shoulder and upper arm
CategoryS46Injury of muscle, fascia and tendon at shoulder and upper arm level
This CodeS46.399DOther injury of muscle, fascia and tendon of triceps, unspecified arm, subsequent encounter

Present on Admission (POA)Billing

S46.399D 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.

  • Complete division, triceps tendon
  • Partial division, triceps tendon

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Injury of muscle, fascia and tendon at shoulder and upper arm level (S46). 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 INJ062
Injury to nerves, muscles and tendons, subsequent encounter
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 S46.399D to ICD-9-CMHistory

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

ICD-9-CM
V58.89 Other specfied aftercare
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 S46.399DOverview

Is S46.399D a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other injury of muscle, fascia and tendon of triceps, unspecified arm, subsequent encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character D in S46.399D mean?

The final character D marks a subsequent encounter: use it for routine care while the other injury of muscle, fascia and tendon of triceps, unspecified arm is healing, after active treatment has ended.

What MS-DRG does S46.399D group to?

When other injury of muscle, fascia and tendon of triceps, unspecified arm, subsequent encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 949, 950, with relative weights from 0.6277 to 1.1897 depending on complications. Higher weights mean higher Medicare reimbursement.

Is S46.399D 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 other injury of muscle, fascia and tendon of triceps, unspecified arm, subsequent encounter on inpatient claims.

What is the ICD-9 equivalent of S46.399D?

Under the General Equivalence Mappings, other injury of muscle, fascia and tendon of triceps, unspecified arm, subsequent encounter converts to ICD-9-CM V58.89 (other specfied aftercare). 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.