2026 ICD-10-CM Diagnosis Code S21.209SUnspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, sequela

ICD-10-CM Codes›S00–T88›S20-S29›S21

ICD-10-CM S21.209S
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S21.209S is a billable ICD-10-CM diagnosis code for unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. 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. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury, sequela.

Code Identity

ICD-10-CM Code
S21.209S
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, sequela
Short Description
Unsp opn wnd unsp bk wl of thorax w/o penet thor cav, sqla
Parent Code
S21.209
Unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS20-S29Injuries to the thorax
CategoryS21Open wound of thorax
This CodeS21.209SUnspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, sequela

Present on Admission (POA)Billing

S21.209S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

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.

CCSR INJ073
Injury, sequela
Default principal diagnosis: inpatient Yes · outpatient Yes

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 S21.209S to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
906.0 Lt eff opn wnd head/trnk
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About S21.209SOverview

Is S21.209S 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, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character S in S21.209S mean?

The final character S makes this a sequela code: it reports a lingering problem that remains after the unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity itself has resolved, not the original event.

What MS-DRG does S21.209S group to?

When unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 604, 605, with relative weights from 0.9160 to 1.4721 depending on complications. Higher weights mean higher Medicare reimbursement.

Is S21.209S 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 unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, sequela on inpatient claims.

What is the ICD-9 equivalent of S21.209S?

Under the General Equivalence Mappings, unspecified open wound of unspecified back wall of thorax without penetration into thoracic cavity, sequela converts to ICD-9-CM 906.0 (lt eff opn wnd head/trnk). 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.