M87.021
BillableIdiopathic aseptic necrosis of right humerus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M87.021 an HCC code?
Yes. M87.021 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 M87.021
For M87.021 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 M87.021 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M87.021 is the ICD-10-CM diagnosis code for idiopathic aseptic necrosis of right humerus. Death of bone tissue without infection in the right upper arm bone (humerus), occurring without a known cause. M87.021 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, M87.021 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, M87.021 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.
Distinguish between humerus necrosis and shoulder necrosis; humerus is the arm bone below the shoulder. Because M87.021 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 M87.021 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Distinguish between humerus necrosis and shoulder necrosis; humerus is the arm bone below the shoulder
- •Verify right side is clearly documented to avoid miscoding as left or unspecified
Clinical Significance
Idiopathic aseptic necrosis of the right humerus represents bone death in the upper arm bone without identifiable cause, often leading to significant functional limitations and chronic pain. This condition frequently requires surgical intervention and long-term orthopedic management to preserve arm function and prevent further bone collapse.
Documentation Requirements
- ✓Documentation of aseptic necrosis specifically involving right humerus
- ✓Confirmation of idiopathic etiology with no identifiable underlying cause
- ✓Imaging evidence showing bone necrosis in right humeral structures
- ✓Clear laterality documentation specifying right side involvement
- ✓Exclusion of infectious processes through clinical evaluation
- ✓Assessment of upper extremity function and range of motion
- ✓Treatment plan including surgical or conservative management options
- ✓Documentation of pain levels and functional impairment