2027 ICD-10-CM Diagnosis Code S94.21XAInjury of deep peroneal nerve at ankle and foot level, right leg, initial encounter

ICD-10-CM Codes›S00–T88›S90-S99›S94

ICD-10-CM S94.21XA
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

S94.21XA is a billable ICD-10-CM diagnosis code for injury of deep peroneal nerve at ankle and foot level, right leg, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 73 through 74, 963 through 965. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury to nerves, muscles and tendons, initial encounter.

Code Identity

ICD-10-CM Code
S94.21XA
Billable Status
Yes — Valid for Submission
Code Describes
Injury of deep peroneal nerve at ankle and foot level, right leg, initial encounter
Short Description
Injury of deep peroneal nrv at ank/ft level, right leg, init
Parent Code
S94.21
Injury of deep peroneal nerve at ankle and foot level, right leg

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS90-S99Injuries to the ankle and foot
CategoryS94Injury of nerves at ankle and foot level
This CodeS94.21XAInjury of deep peroneal nerve at ankle and foot level, right leg, initial encounter

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Injury of nerves at ankle and foot level (S94). 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 2027, published by CMS and the National Center for Health Statistics.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to S94.21XA: its own notes plus those printed at S94, block S90-S99, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Block S90-S99 Injuries to the ankle and foot applies to 3,324 codes
  • burns and corrosions (T20-T32)
  • fracture of ankle and malleolus (S82.-)
  • frostbite (T33-T34)
  • insect bite or sting, venomous (T63.4)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • code to identify any retained foreign body, if applicable (Z18.-)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From S94 Injury of nerves at ankle and foot level applies to 54 codes
  • any associated open wound (S91.-)

Notes

General instructions on how these codes are used.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

7th Character

Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.

From S94 Injury of nerves at ankle and foot level applies to 54 codes
  • The appropriate 7th character is to be added to each code from category S94
Values for category S94 Encounter: Initial, Subsequent, Sequela
  • Ainitial encounter this code
  • Dsubsequent encounter
  • Ssequela

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name S94.21XA, its category, or a range that includes it.

Excludes2 2

These codes carry an Excludes2 note naming S94.21XA: its condition is not part of those codes, and both may be reported when the patient has both.

  • S74 Injury of nerves at hip and thigh level
    injury of nerves at ankle and foot level (S94.-) names S94.-, which includes this code
  • S84 Injury of nerves at lower leg level
    injury of nerves at ankle and foot level (S94.-) names S94.-, which includes this code

Clinical ClassificationClinical

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

CCSR INJ025
Injury to nerves, muscles and tendons, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Leg Injuries and Disorders

Your legs are made up of bones, blood vessels, muscles, and other connective tissue. They are important for motion and standing. Playing sports, running, falling, or having an accident can damage your legs. Common leg injuries include sprains and strains, joint dislocations, and fractures (broken bones).

Read the full article at MedlinePlus

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

Convert S94.21XA to ICD-9-CMHistory

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

ICD-9-CM
956.3 Injury peroneal nerve
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About S94.21XAOverview

Is S94.21XA a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report injury of deep peroneal nerve at ankle and foot level, right leg, initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What does the 7th character A in S94.21XA mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for injury of deep peroneal nerve at ankle and foot level, right leg, such as an emergency visit or first evaluation.

What MS-DRG does S94.21XA group to?

When injury of deep peroneal nerve at ankle and foot level, right leg, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 964, 965, 74, 73, 963, with relative weights from 1.0054 to 2.6361 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S94.21XA?

Under the General Equivalence Mappings, injury of deep peroneal nerve at ankle and foot level, right leg, initial encounter converts to ICD-9-CM 956.3 (injury peroneal nerve). The mapping is approximate, so confirm the match fits the documentation.