M86.651
BillableOther chronic osteomyelitis, right thigh
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.651 an HCC code?
Yes. M86.651 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 M86.651
For M86.651 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 M86.651 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.651 is the ICD-10-CM diagnosis code for other chronic osteomyelitis, right thigh. A chronic bone infection in the right thigh bone (femur) that persists over time with ongoing bone inflammation and potential complications. M86.651 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, M86.651 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, M86.651 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 thigh' is documented and verify this is chronic rather than acute osteomyelitis. Because M86.651 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 M86.651 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm 'right thigh' is documented and verify this is chronic rather than acute osteomyelitis
- •Document any weight-bearing limitations or mobility restrictions related to the infection
Clinical Significance
Other chronic osteomyelitis of the right thigh represents a persistent bone infection specifically affecting the right femur, indicating significant morbidity that impacts weight-bearing, mobility, and overall functional capacity. This condition requires intensive medical management including prolonged antibiotic therapy and potential surgical intervention, substantially affecting patient independence and quality of life.
Documentation Requirements
- ✓Clear documentation of chronic osteomyelitis diagnosis
- ✓Specific anatomic identification of right thigh (femur) involvement
- ✓Evidence of chronic duration and persistent infection
- ✓Laboratory studies including inflammatory markers and cultures
- ✓Imaging studies confirming right femur bone infection
- ✓Treatment history including antibiotic regimens and duration
- ✓Assessment of weight-bearing status and mobility limitations
- ✓Documentation of any surgical interventions or complications