M87.035
BillableIdiopathic aseptic necrosis of left ulna
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M87.035 an HCC code?
Yes. M87.035 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 M87.035
For M87.035 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 M87.035 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M87.035 is the ICD-10-CM diagnosis code for idiopathic aseptic necrosis of left ulna. Death of bone tissue in the left ulna (forearm bone) without infection, occurring without a known cause. M87.035 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, M87.035 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, M87.035 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 left side is clearly documented in the clinical notes or imaging reports. Because M87.035 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 M87.035 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm left side is clearly documented in the clinical notes or imaging reports
- •This code is specific to the left ulna; do not use for bilateral or unspecified cases
Clinical Significance
Idiopathic aseptic necrosis of the left ulna involves bone death in the medial forearm without known cause, potentially compromising elbow joint stability and forearm function. This serious orthopedic condition often requires comprehensive management including pain control and possible surgical intervention to maintain arm function.
Documentation Requirements
- ✓Clear documentation of aseptic necrosis affecting left ulna bone
- ✓Confirmation of idiopathic nature without identifiable underlying cause
- ✓Radiological evidence demonstrating bone necrosis in left ulnar bone
- ✓Specific laterality documentation indicating left side involvement
- ✓Clinical exclusion of infectious etiology
- ✓Functional assessment of left elbow and forearm mobility
- ✓Treatment approach documentation including therapeutic interventions
- ✓Pain assessment and impact on activities involving left arm