M87.09
BillableIdiopathic aseptic necrosis of bone, multiple sites
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M87.09 an HCC code?
Yes. M87.09 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 M87.09
For M87.09 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 M87.09 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M87.09 is the ICD-10-CM diagnosis code for idiopathic aseptic necrosis of bone, multiple sites. Death of bone tissue affecting multiple bones throughout the body, occurring without a known cause. M87.09 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, M87.09 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, M87.09 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.
This code indicates involvement of 2 or more separate bone sites. Because M87.09 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 M87.09 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code indicates involvement of 2 or more separate bone sites
- •Consider documenting which specific sites are affected for clinical clarity
Clinical Significance
Idiopathic aseptic necrosis affecting multiple bone sites represents a systemic condition of bone death without infection or identifiable cause, indicating significant disease burden requiring comprehensive management. This diagnosis suggests a more severe condition that may impact multiple functional areas and require multidisciplinary care coordination.
Documentation Requirements
- ✓Documentation of multiple bone sites affected
- ✓Specification of at least two distinct anatomical locations
- ✓Confirmation of aseptic nature across all sites
- ✓Documentation that cause is idiopathic/unknown
- ✓Imaging evidence of osteonecrosis at multiple locations
- ✓Clinical findings consistent with multi-site involvement
- ✓Exclusion of systemic causes that could explain multiple sites
- ✓Comprehensive functional assessment
Commonly Confused Codes
- •M87.19 — Drug-induced osteonecrosis of multiple sites (requires medication cause)
- •M87.29 — Trauma-related osteonecrosis of multiple sites (requires injury history)
- •M87.39 — Other secondary osteonecrosis of multiple sites (requires underlying condition)
- •Single-site idiopathic osteonecrosis codes (use when only one site affected)
- •M86.9 — Osteomyelitis unspecified (infectious process)