2026 ICD-10-CM Diagnosis Code S09.10XAUnspecified injury of muscle and tendon of head, initial encounter
S09.10XA is a billable ICD-10-CM diagnosis code for unspecified injury of muscle and tendon of head, 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 913 through 914, 963 through 965. Coders also document this condition as injury of fascia of head. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury to nerves, muscles and tendons, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Injury of fascia of head
- Injury of muscle and tendon of head
- Injury of muscle of head
- Injury of tendon of head
- Traumatic division of tendon of head and neck
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Other and unspecified injuries of head (S09). 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.
Patient EducationClinical
Head Injuries
Chances are you've bumped your head before. Often, the injury is minor because your skull is hard and it protects your brain. But other head injuries can be more severe, such as a skull fracture, concussion, or traumatic brain injury.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S09.10XA to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S09.10XAOverview
Is S09.10XA (Unspecified injury of muscle and tendon of head) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report unspecified injury of muscle and tendon of head, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in S09.10XA mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for unspecified injury of muscle and tendon of head, such as an emergency visit or first evaluation.
What MS-DRG does S09.10XA group to?
When unspecified injury of muscle and tendon of head, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 913, 914, 963, 964, 965, with relative weights from 0.8855 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of S09.10XA?
Under the General Equivalence Mappings, unspecified injury of muscle and tendon of head, initial encounter converts to ICD-9-CM 959.01 (head 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.
