2026 ICD-10-CM Diagnosis Code S21.209AUnspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, initial encounter
S21.209A is a billable ICD-10-CM diagnosis code for unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, 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 of trunk, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Anterior cord syndrome due to injury at T7-T12 level
- Anterior cord syndrome due to open fracture of T7-T12 level
- 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 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
- Complete lesion of thoracic spinal cord due to open subluxation of joint of thoracic spine
- Degloving injury back
- Degloving injury chest wall
- Degloving injury of trunk
- Degloving injury, scapular area
- Degloving injury, shoulder area
- Dislocation of costovertebral joint
- Dislocation of scapulothoracic joint
- Fracture of first thoracic vertebra
- Fracture of fourth thoracic vertebra
- Fracture of second thoracic vertebra
- Fracture of third thoracic vertebra
- Glass in back
- 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 of scapula
- Open dislocation thoracic spine
- Open fracture of first thoracic vertebra
- Open fracture of fourth thoracic vertebra
- Open fracture of second thoracic vertebra
- Open fracture of T7-T12 level with incomplete spinal cord lesion
- Open fracture of T7-T12 level with spinal cord injury
- Open fracture of third thoracic vertebra
- Open fracture of thoracic spine with spinal cord injury
- Open spinal dislocation with complete thoracic cord lesion
- Open subluxation thoracic spine
- Open traumatic dislocation costovertebral joint
- Open traumatic dislocation of scapulothoracic joint
- Open wound of back
- Open wound of back wall of thorax
- Open wound of scapular region
- 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
- Traumatic anterior cord syndrome
- Traumatic dislocation of scapulothoracic joint
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Open wound of thorax (S21). 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
Back Injuries
Your back is made of bones, muscles, and other tissues extending from your neck to your pelvis. Back injuries can result from sports injuries, work around the house or in the garden, or a sudden jolt such as a car accident. The lower back is the most common site of back injuries and back pain. Common back injuries include :
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S21.209A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S21.209AOverview
Is S21.209A a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in S21.209A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, such as an emergency visit or first evaluation.
What MS-DRG does S21.209A group to?
When unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, 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 S21.209A?
Under the General Equivalence Mappings, unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, initial encounter converts to ICD-9-CM 876.0 (open wound of back). 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.
