Question 1

What is ICD-10 code S81?

Accepted Answer

S81 is the ICD-10-CM diagnosis code for Open wound of knee and lower leg. It belongs to the ICD-10-CM chapter for injury, poisoning and certain other consequences of external causes (s00-t88). S81 is a non-billable header code that organizes more specific child codes; the actual diagnosis on a claim must use one of those children. S81 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Question 2

Is S81 an HCC code?

Accepted Answer

S81 is a non-billable header code, so it cannot itself be a payment HCC. Header codes organize more specific child codes that share the same root concept; one of those children may map to a payment HCC under the CMS-HCC V28 or V24 risk adjustment model. Coders should select a child code from the S81 hierarchy that matches the documented presentation, then check that specific child for HCC status.

Question 3

Is S81 billable?

Accepted Answer

No. S81 is a header (non-billable) ICD-10-CM code. Header codes sit at a higher level of the diagnosis hierarchy and exist to organize a family of more specific child codes. Per ICD-10-CM coding guidelines, a header code cannot be reported on a claim as the diagnosis, coders must select a billable child code from the S81 hierarchy that matches the highest level of specificity supported by the provider's documentation. Payers reject header codes submitted as the primary diagnosis.

HCC Buddy Code Card

S81

What This Code Means

Excludes 1, Do NOT code together

Excludes 2, Not included here, may code separately

Code Also

Child Codes

Code Hierarchy

Open S81 in the Interactive Encoder

S81 ICD-10-CM Code: Open wound of knee and lower leg