M87.329
BillableOther secondary osteonecrosis, unspecified humerus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M87.329 an HCC code?
Yes. M87.329 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 M87.329
For M87.329 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 M87.329 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M87.329 is the ICD-10-CM diagnosis code for other secondary osteonecrosis, unspecified humerus. Death of bone tissue in the upper arm bone (humerus) of unspecified side caused by a secondary condition or factor. M87.329 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, M87.329 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, M87.329 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.
Query the provider for laterality information when not documented. Because M87.329 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 M87.329 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Query the provider for laterality information when not documented
- •Use only when bilateral involvement is not present and laterality truly cannot be determined
Clinical Significance
Unspecified humerus secondary osteonecrosis represents bone death from identifiable non-traumatic causes when laterality cannot be determined. This condition significantly impacts upper extremity function and requires management of both the underlying condition and bone pathology.
Documentation Requirements
- ✓Documentation of underlying secondary cause of osteonecrosis
- ✓Imaging evidence of humeral osteonecrosis without specified side
- ✓Clinical findings consistent with humeral dysfunction
- ✓Documentation explaining why laterality is unspecified
- ✓History of predisposing factors for secondary osteonecrosis
- ✓Exclusion of traumatic and idiopathic causes
- ✓Provider assessment of secondary nature
- ✓Evidence of bone death through diagnostic studies