2026 ICD-10-CM Diagnosis Code S66.091DOther specified injury of long flexor muscle, fascia and tendon of right thumb at wrist and hand level, subsequent encounter
S66.091D is a billable ICD-10-CM diagnosis code for other specified injury of long flexor muscle, fascia and tendon of right thumb at wrist and hand level, 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury to nerves, muscles and tendons, subsequent encounter.
Code Identity
Code Classification
Present on Admission (POA)Billing
S66.091D is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Injury of muscle, fascia and tendon at wrist and hand level (S66). 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
Hand Injuries and Disorders
No matter how old you are or what you do for a living, you are always using your hands. When there is something wrong with them, you may not be able to do your regular activities.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S66.091D to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S66.091DOverview
Is S66.091D a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report other specified injury of long flexor muscle, fascia and tendon of right thumb at wrist and hand level, subsequent encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character D in S66.091D mean?
The final character D marks a subsequent encounter: use it for routine care while the other specified injury of long flexor muscle, fascia and tendon of right thumb at wrist and hand level is healing, after active treatment has ended.
What MS-DRG does S66.091D group to?
When other specified injury of long flexor muscle, fascia and tendon of right thumb at wrist and hand level, 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 S66.091D 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 specified injury of long flexor muscle, fascia and tendon of right thumb at wrist and hand level, subsequent encounter on inpatient claims.
What is the ICD-9 equivalent of S66.091D?
Under the General Equivalence Mappings, other specified injury of long flexor muscle, fascia and tendon of right thumb at wrist and hand level, 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.
