M79.A21
BillableNontraumatic compartment syndrome of right lower extremity
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M79.A21 an HCC code?
No. M79.A21 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
M79.A21 is the ICD-10-CM diagnosis code for nontraumatic compartment syndrome of right lower extremity. A serious condition where pressure builds up in the muscle compartments of the right leg without trauma, potentially restricting blood flow and damaging tissues. M79.A21 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering other soft tissue disorders (m70-m79).
M79.A21 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Compartment syndrome is a medical emergency; verify documentation confirms nontraumatic etiology.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M79.A21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Compartment syndrome is a medical emergency; verify documentation confirms nontraumatic etiology
- •Ensure laterality (right) is clearly documented; do not assume based on clinical presentation