2026 ICD-10-CM Diagnosis Code S91.009AUnspecified open wound, unspecified ankle, initial encounter

ICD-10-CM Codes›S00–T88›S90-S99›S91

ICD-10-CM S91.009A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S91.009A is a billable ICD-10-CM diagnosis code for unspecified open wound, unspecified ankle, 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 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 604 through 605, 963 through 965. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Open wounds to limbs, initial encounter.

Code Identity

ICD-10-CM Code
S91.009A
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified open wound, unspecified ankle, initial encounter
Short Description
Unspecified open wound, unspecified ankle, initial encounter
Same as the full description in the CMS dataset.
Parent Code
S91.009
Unspecified open wound, unspecified ankle

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS90-S99Injuries to the ankle and foot
CategoryS91Open wound of ankle, foot and toes
This CodeS91.009AUnspecified open wound, unspecified ankle, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Fracture dislocation of ankle joint
  • Fracture subluxation of ankle joint
  • Glass in ankle
  • Multiple open wounds of ankle
  • Multiple open wounds of lower limb
  • Open dislocation of ankle
  • Open dislocation of distal end of tibia
  • Open dislocation of navicular bone of foot
  • Open dislocation of talus
  • Open division ankle ligament
  • Open division ankle, lateral ligament
  • Open division ankle, medial ligament
  • Open division calcaneofibular ligament
  • Open division distal tibiofibular ligament
  • Open division ligament ankle and/or foot
  • Open fracture dislocation of ankle joint
  • Open fracture of ankle
  • Open fracture of talus
  • Open fracture subluxation of ankle joint
  • Open fracture talus, body
  • Open fracture talus, head
  • Open fracture talus, neck
  • Open traumatic subluxation ankle joint
  • Open wound of ankle
  • Subluxation of ankle joint

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Open wound of ankle, foot and toes (S91). 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 INJ012
Open wounds to limbs, initial encounter
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 S91.009A to ICD-9-CMHistory

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

ICD-9-CM
891.0 Open wnd knee/leg/ankle
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 S91.009AOverview

Is S91.009A (Unspecified open wound, unspecified ankle) a billable code?

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

What does the 7th character A in S91.009A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for unspecified open wound, unspecified ankle, such as an emergency visit or first evaluation.

What MS-DRG does S91.009A group to?

When unspecified open wound, unspecified ankle, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 604, 605, 963, 964, 965, with relative weights from 0.9160 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S91.009A?

Under the General Equivalence Mappings, unspecified open wound, unspecified ankle, initial encounter converts to ICD-9-CM 891.0 (open wnd knee/leg/ankle). 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.