M12.08
BillableChronic postrheumatic arthropathy [Jaccoud], other specified site
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M12.08 an HCC code?
Yes. M12.08 maps to Reactive and Specified Arthropathies under the CMS-HCC V28 risk adjustment model (and Rheumatoid Arthritis and Inflammatory Connective Tissue Disease under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for M12.08
For M12.08to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed M12.08 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M12.08 is the ICD-10-CM diagnosis code for chronic postrheumatic arthropathy [jaccoud], other specified site. A chronic joint condition developing after rheumatic fever that affects areas of the body other than the shoulder, elbow, wrist, hip, knee, or ankle/foot. M12.08 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering inflammatory polyarthropathies (m05-m14).
Under the CMS-HCC V28 risk adjustment model, M12.08 maps to Reactive and Specified Arthropathies (HCC 94) with a community, non-dual, aged base RAF weight of 0.000. Under the older CMS-HCC V24 model, M12.08 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease (HCC 40) with a community, non-dual, aged base RAF weight of 0.307. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Document the specific anatomical site affected in the medical record for clarity. Because M12.08 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M12.08 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the specific anatomical site affected in the medical record for clarity
- •This code is for uncommon sites; verify the site does not fit other M12.0x subcategories
Clinical Significance
Chronic postrheumatic arthropathy affecting other specified sites indicates Jaccoud's arthropathy in unusual locations following rheumatic fever, potentially requiring specialized assessment and management approaches. This condition necessitates ongoing care while monitoring for cardiac complications associated with underlying rheumatic heart disease.
Documentation Requirements
- ✓Established history of rheumatic fever
- ✓Specific documentation of unusual joint site affected
- ✓Evidence of chronic, reversible joint deformities
- ✓Clinical findings consistent with postrheumatic arthropathy
- ✓Imaging showing absence of joint erosions
- ✓Assessment of function at the affected site
- ✓Current cardiac evaluation and status
- ✓Treatment plan tailored to specific location