2026 ICD-10-CM Diagnosis Code S23.100ASubluxation of unspecified thoracic vertebra, initial encounter
S23.100A is a billable ICD-10-CM diagnosis code for subluxation of unspecified thoracic vertebra, 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 551 through 552, 963 through 965. 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.
- Anterior lesion of thoracic spinal cord due to closed dislocation of joint of thoracic spine
- Anterior lesion of thoracic spinal cord due to closed subluxation of joint of thoracic spine
- Anterior lesion of thoracic spinal cord due to open dislocation of joint of thoracic spine
- Anterior lesion of thoracic spine due to open subluxation of joint of thoracic spine
- Central cord syndrome of thoracic spinal cord due to closed dislocation of joint of thoracic spine
- Central cord syndrome of thoracic spinal cord due to closed subluxation of joint of thoracic spine
- Central cord syndrome of thoracic spinal cord due to open dislocation of joint of thoracic spine
- Central cord syndrome of thoracic spinal cord due to open subluxation of joint of thoracic spine
- Central cord syndrome of thoracic spinal cord due to traumatic injury
- Closed spinal dislocation with complete thoracic cord lesion
- Closed subluxation thoracic spine
- Complete lesion of thoracic spinal cord due to closed subluxation of joint of thoracic spine
- Complete lesion of thoracic spinal cord due to open subluxation of joint of thoracic spine
- Lesion of thoracic spinal cord due to closed dislocation of joint of thoracic spine
- Lesion of thoracic spinal cord due to open dislocation of joint of thoracic spine
- Lesion of thoracic spinal cord due to subluxation of joint of thoracic spine
- Open dislocation thoracic spine
- Open spinal dislocation with complete thoracic cord lesion
- Open subluxation thoracic spine
- Posterior cord syndrome of thoracic spinal cord due to closed dislocation of joint of thoracic spine
- Posterior cord syndrome of thoracic spinal cord due to closed subluxation of joint of thoracic spine
- Posterior cord syndrome of thoracic spinal cord due to open dislocation of joint of thoracic spine
- Posterior cord syndrome of thoracic spinal cord due to open subluxation of joint of thoracic spine
- Subluxation of joint of thoracic spine
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Dislocation and sprain of joints and ligaments of thorax (S23). 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.
Read the full article at MedlinePlus
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Convert S23.100A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S23.100AOverview
Is S23.100A (Subluxation of unspecified thoracic vertebra) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report subluxation of unspecified thoracic vertebra, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in S23.100A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for subluxation of unspecified thoracic vertebra, such as an emergency visit or first evaluation.
What MS-DRG does S23.100A group to?
When subluxation of unspecified thoracic vertebra, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 551, 552, 963, 964, 965, with relative weights from 0.9405 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of S23.100A?
Under the General Equivalence Mappings, subluxation of unspecified thoracic vertebra, initial encounter converts to ICD-9-CM 839.21 (disloc thoracic vert-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.
