2026 ICD-10-CM Diagnosis Code S83.429DSprain of lateral collateral ligament of unspecified knee, subsequent encounter
S83.429D is a billable ICD-10-CM diagnosis code for sprain of lateral collateral ligament of unspecified knee, 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. Coders also document this condition as complete tear, knee ligament. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Sprains and strains, subsequent encounter.
Code Identity
Code Classification
Present on Admission (POA)Billing
S83.429D 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.
- Complete tear, knee ligament
- Complete tear, knee, lateral collateral ligament
- Injury of lateral collateral ligament of knee
- Partial rupture of ligament
- Partial tear, knee, lateral collateral ligament
- Rupture of lateral collateral ligament of knee
- Sprain of lateral collateral ligament of knee
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Dislocation and sprain of joints and ligaments of knee (S83). 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
Knee Injuries and Disorders
Your knee joint is made up of bone, cartilage, ligaments and fluid. Muscles and tendons help the knee joint move. When any of these structures is hurt or diseased, you have knee problems. Knee problems can cause pain and difficulty walking.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S83.429D to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S83.429DOverview
Is S83.429D (Sprain of lateral collateral ligament of unspecified knee) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report sprain of lateral collateral ligament of unspecified knee, subsequent encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character D in S83.429D mean?
The final character D marks a subsequent encounter: use it for routine care while the sprain of lateral collateral ligament of unspecified knee is healing, after active treatment has ended.
What MS-DRG does S83.429D group to?
When sprain of lateral collateral ligament of unspecified knee, 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 S83.429D 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 sprain of lateral collateral ligament of unspecified knee, subsequent encounter on inpatient claims.
What is the ICD-9 equivalent of S83.429D?
Under the General Equivalence Mappings, sprain of lateral collateral ligament of unspecified knee, 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.
