2026 ICD-10-CM Diagnosis Code S63.042ASubluxation of carpometacarpal joint of left thumb, initial encounter
S63.042A is a billable ICD-10-CM diagnosis code for subluxation of carpometacarpal joint of left thumb, 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 562 through 563, 963 through 965. Coders also document this condition as left carpometacarpal joint subluxation. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Dislocations, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Left carpometacarpal joint subluxation
- Left thumb subluxation
- Subluxation of carpometacarpal joint of left thumb
- Subluxation of joint of left wrist region
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Dislocation and sprain of joints and ligaments at wrist and hand level (S63). 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
Dislocations
Dislocations are joint injuries that force the ends of your bones out of position. The cause is often a fall or a blow, sometimes from playing a contact sport. You can dislocate your ankles, knees, shoulders, hips, elbows and jaw. You can also dislocate your finger and toe joints.
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Convert S63.042A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S63.042AOverview
Is S63.042A (Subluxation of carpometacarpal joint of left thumb) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report subluxation of carpometacarpal joint of left thumb, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in S63.042A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for subluxation of carpometacarpal joint of left thumb, such as an emergency visit or first evaluation.
What MS-DRG does S63.042A group to?
When subluxation of carpometacarpal joint of left thumb, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 562, 563, 963, 964, 965, with relative weights from 0.8955 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of S63.042A?
Under the General Equivalence Mappings, subluxation of carpometacarpal joint of left thumb, initial encounter converts to ICD-9-CM 833.04 (disloc carpometacarp-cl). 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.
