M87.851
BillableOther osteonecrosis, right femur
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M87.851 an HCC code?
Yes. M87.851 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 M87.851
For M87.851 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 M87.851 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M87.851 is the ICD-10-CM diagnosis code for other osteonecrosis, right femur. Death of bone tissue in the right thighbone (femur) due to interrupted blood supply, commonly affecting the femoral head. M87.851 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, M87.851 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, M87.851 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.
Femoral head osteonecrosis is the most common site; document whether it involves the head, neck, or shaft. Because M87.851 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 M87.851 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Femoral head osteonecrosis is the most common site; document whether it involves the head, neck, or shaft
- •Verify right-sided involvement and consider if this is post-traumatic or idiopathic
Clinical Significance
Right femur osteonecrosis is a serious condition that can lead to femoral head collapse and severe hip dysfunction. This diagnosis has significant risk adjustment implications due to the high likelihood of requiring major orthopedic surgery, prolonged rehabilitation, and potential long-term disability affecting mobility and independence.
Documentation Requirements
- ✓Specific identification of the right femur as affected by osteonecrosis
- ✓Documentation of causes other than idiopathic or drug-induced osteonecrosis
- ✓Advanced imaging (MRI, CT scan) confirming right femoral bone necrosis
- ✓Clinical symptoms including right hip pain, limited range of motion, and weight-bearing difficulty
- ✓Exclusion of infectious or traumatic causes as primary etiology
- ✓Assessment of impact on ambulation and activities of daily living
- ✓Documentation of disease stage and extent of femoral head involvement
- ✓Provider evaluation of surgical options and prognosis