M87.065 ICD-10-CM Code: Idiopathic aseptic necrosis of left fibula
M87.065 maps to CMS-HCC V28 92 (RAF 0.479). Documentation must support MEAT. MEAT criteria · RAF calculator · free HCC coding tools
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Other osteopathies (M86-M90)
M87.065
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceIdiopathic aseptic necrosis of left fibula
Death of bone tissue in the left fibula (smaller bone in the lower leg) without infection, occurring without a known cause.
Buddy Insight
Idiopathic aseptic necrosis of the left fibula represents bone death without infection in the smaller bone of the lower leg, occurring without identifiable cause.
CMS-HCC V28
MappedHCC 92
RAF 0.479
CMS-HCC V24
MappedHCC 39
RAF 0.401
ACA/HHS
MappedHCC 55
Varies by metal level
ESRD/PACE
MappedHCC 39
RAF 0.092
RXHCC
MappedHCC 80
RAF 0.204
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for M87.065 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M87.065 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M87.065 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M87.065 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M87.065 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M87.065 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M87.065 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is M87.065 an HCC code?
Yes. M87.065 (Idiopathic aseptic necrosis of left fibula) maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis under the CMS-HCC V28 risk adjustment model (and Bone/Joint/Muscle Infections/Necrosis under V24), with a community non-dual aged RAF of 0.479. It is billable for payment year 2026.
Coder answer: M87.065 is billable and maps to V28 HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- M87.065
- Description
- Idiopathic aseptic necrosis of left fibula
- HCC (V28)
- HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
- RAF
- 0.479
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. 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.
Work M87.065 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for M87.065
For M87.065 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 M87.065 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
Get the V28 RAF + MEAT cheat sheet
One printable page: confirm a code's V28 HCC status, its RAF weight, and the MEAT your note needs to make it stick. Free, no card.
Free PDF. No card. Unsubscribe anytime.
What This Code Means
M87.065 is the ICD-10-CM diagnosis code for idiopathic aseptic necrosis of left fibula. Death of bone tissue in the left fibula (smaller bone in the lower leg) without infection, occurring without a known cause. M87.065 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, M87.065 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis (HCC 92) with a community, non-dual, aged base RAF weight of 0.479. Under the older CMS-HCC V24 model, M87.065 maps to Bone/Joint/Muscle Infections/Necrosis (HCC 39) with a community, non-dual, aged base RAF weight of 0.401. 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.
Verify laterality is documented as 'left' in the medical record before assigning this code. Because M87.065 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 M87.065 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify laterality is documented as 'left' in the medical record before assigning this code
- •Ensure the necrosis is idiopathic (no trauma, radiation, or other identifiable cause) to distinguish from other M87 subcategories
Clinical Significance
Idiopathic aseptic necrosis of the left fibula represents bone death without infection in the smaller bone of the lower leg, occurring without identifiable cause. This condition can compromise lower leg stability and weight-bearing capacity, potentially requiring surgical intervention and carrying risk for pathological fracture and functional impairment.
Documentation Requirements
- ✓Clear documentation of aseptic necrosis diagnosis
- ✓Specification of left fibula involvement
- ✓Evidence supporting idiopathic (unknown) etiology
- ✓Imaging studies confirming bone necrosis without infection
- ✓Exclusion of traumatic, vascular, or medication-related causes
- ✓Assessment of lower leg stability and function
- ✓Documentation ruling out infectious osteomyelitis
- ✓Treatment plan addressing bone death and functional preservation