M87.335
BillableOther secondary osteonecrosis of left ulna
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M87.335 an HCC code?
Yes. M87.335 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 M87.335
For M87.335 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 M87.335 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M87.335 is the ICD-10-CM diagnosis code for other secondary osteonecrosis of left ulna. Death of bone tissue in the left forearm bone (ulna) caused by an underlying condition or injury, resulting in bone deterioration and potential collapse. M87.335 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, M87.335 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, M87.335 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.
Document the etiology of secondary osteonecrosis to support medical necessity and potential causation. Because M87.335 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 M87.335 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the etiology of secondary osteonecrosis to support medical necessity and potential causation
- •Confirm left side laterality is documented in the clinical record to justify this specific code selection
Clinical Significance
Left ulna secondary osteonecrosis indicates bone death from identifiable non-traumatic causes affecting the dominant forearm in most patients. This condition significantly impacts forearm mechanics and may require surgical intervention to preserve function and prevent collapse.
Documentation Requirements
- ✓Clear documentation of secondary cause of osteonecrosis
- ✓Radiological evidence of bone necrosis in left ulna
- ✓Clinical assessment demonstrating left forearm impairment
- ✓History of risk factors or predisposing conditions
- ✓Exclusion of trauma and idiopathic causes
- ✓Documentation of functional limitations and symptoms
- ✓Provider correlation of secondary etiology
- ✓Evidence of compromised bone viability through imaging
Commonly Confused Codes
- •M87.035 — Idiopathic osteonecrosis of left ulna (spontaneous onset)
- •M87.235 — Osteonecrosis due to previous trauma of left ulna (traumatic)
- •S52.602A — Unspecified fracture of lower end of left ulna (acute injury)
- •M86.035 — Acute hematogenous osteomyelitis of left ulna (infection)
- •M25.522 — Pain in left elbow (symptom code only)