M87.864
BillableOther osteonecrosis, right fibula
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M87.864 an HCC code?
Yes. M87.864 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 M87.864
For M87.864 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 M87.864 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M87.864 is the ICD-10-CM diagnosis code for other osteonecrosis, right fibula. Death of bone tissue in the right fibula (smaller bone in the lower leg) due to causes other than trauma or radiation. M87.864 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, M87.864 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, M87.864 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 side is documented in the clinical record before coding. Because M87.864 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 M87.864 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm right side is documented in the clinical record before coding
- •Distinguish between fibula osteonecrosis and tibia osteonecrosis, as they have different codes
Clinical Significance
Right fibular osteonecrosis represents avascular bone death in the smaller lower leg bone, potentially affecting ankle stability and weight-bearing function. Though less common than tibial involvement, it requires careful monitoring and management to prevent complications.
Documentation Requirements
- ✓Specific identification of right fibula involvement
- ✓Radiographic or MRI evidence of bone death/necrosis
- ✓Documentation excluding trauma, infection, or radiation as causes
- ✓Assessment of impact on ankle stability and gait
- ✓Pain evaluation and functional limitations
- ✓Underlying risk factor identification
- ✓Treatment plan including activity modifications
- ✓Follow-up imaging schedule for progression monitoring