M86.351
BillableChronic multifocal osteomyelitis, right femur
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.351 an HCC code?
Yes. M86.351 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 M86.351
For M86.351 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 M86.351 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.351 is the ICD-10-CM diagnosis code for chronic multifocal osteomyelitis, right femur. A chronic bone infection affecting multiple areas of the right thighbone (femur), characterized by persistent inflammation and bone damage. M86.351 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, M86.351 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, M86.351 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.
Confirm right femur involvement and multifocal nature of the infection. Because M86.351 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 M86.351 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm right femur involvement and multifocal nature of the infection
- •Distinguish from localized osteomyelitis affecting only one site of the femur
Clinical Significance
Chronic multifocal osteomyelitis of the right femur represents a severe infection of the body's largest bone, with potential for significant morbidity including pathologic fractures and functional impairment. This condition requires aggressive treatment and long-term monitoring due to the femur's weight-bearing function.
Documentation Requirements
- ✓Specific documentation of right femur involvement
- ✓Evidence of chronic infection (>6 weeks or recurrent episodes)
- ✓Confirmation of multifocal pattern within the femur
- ✓Imaging findings demonstrating chronic osteomyelitic changes
- ✓Assessment of weight-bearing capacity and mobility
- ✓Laboratory findings supporting chronic infectious process
- ✓Documentation of treatment modalities and responses
- ✓Provider assessment confirming chronic multifocal osteomyelitis
Commonly Confused Codes
- •M86.151 — Acute osteomyelitis of right femur, differs by chronicity
- •M86.352 — Same condition affecting left femur
- •M86.451 — Chronic osteomyelitis with draining sinus of right femur
- •M86.551 — Other chronic hematogenous osteomyelitis of right femur
- •M87.051 — Idiopathic aseptic necrosis of right femur, non-infectious