M86.09
BillableAcute hematogenous osteomyelitis, multiple sites
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.09 an HCC code?
Yes. M86.09 maps to Bone/Joint/Muscle Infections/Necrosis under the CMS-HCC V28 risk adjustment model (and Bone/Joint/Muscle Infections/Necrosis 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 M86.09
For M86.09 to 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 M86.09 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.09 is the ICD-10-CM diagnosis code for acute hematogenous osteomyelitis, multiple sites. A bacterial bone infection that develops suddenly and spreads through the bloodstream, affecting two or more different bone sites simultaneously. M86.09 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering other osteopathies (m86-m90).
Under the CMS-HCC V28 risk adjustment model, M86.09 maps to Bone/Joint/Muscle Infections/Necrosis (HCC 92) with a community, non-dual, aged base RAF weight of 0.209. Under the older V24 model, M86.09 mapped to the same category but with a base RAF weight of 0.482 — V28 recalibrated weights across the entire model. 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 all affected sites clearly to support the multiple sites diagnosis. Because M86.09 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 M86.09 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document all affected sites clearly to support the multiple sites diagnosis
- •Consider if separate codes for each site would be more appropriate based on payer guidelines
Clinical Significance
Acute hematogenous osteomyelitis involving multiple sites represents the most severe form of bloodstream-disseminated bone infection, indicating systemic disease with high mortality and morbidity risk. This condition requires aggressive IV antibiotic therapy and intensive monitoring to prevent sepsis, multiorgan failure, and permanent disability.
Documentation Requirements
- ✓Documentation of acute hematogenous osteomyelitis
- ✓Clear identification of involvement at multiple bone sites
- ✓Clinical evidence of systemic bone infection
- ✓Imaging studies confirming multifocal osteomyelitis
- ✓Laboratory evidence of severe bacterial infection
- ✓Blood cultures with organism identification and sensitivities
- ✓Documentation of all affected bone sites
- ✓Assessment of disease severity and systemic complications