What is ICD-10 code M87.165?

M87.165 is the ICD-10-CM diagnosis code for Osteonecrosis due to drugs, left fibula. Death of bone tissue in the left fibula (smaller bone in the lower leg) caused by medication side effects, leading to potential bone collapse. M87.165 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M87.165 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. M87.165 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. M87.165 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does M87.165 map to under V28?

M87.165 does not map to a CMS-HCC V28 payment category. Check the current CMS-HCC V28 model file for payment year 2026 rather than an older V24 tip sheet.

What does M87.165 pay in RAF?

M87.165 has no separately stated V28 community RAF weight. If it is not a V28 payment HCC, it adds nothing to a community RAF score.

What is the V28 vs V24 difference for M87.165?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. M87.165 was a payment HCC under V24 (Bone/Joint/Muscle Infections/Necrosis) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

What documentation supports M87.165?

Confirm left fibula involvement through imaging reports or clinical examination documentation Link this diagnosis to the specific medication in the patient's medication history for complete clinical context Because M87.165 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM M87.165: Osteonecrosis due to drugs

M87.165 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · HCC Buddy coding tools

ICD-10-CM Code View

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Code lookupM87.165Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Other osteopathies (M86-M90)

M87.165

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Osteonecrosis due to drugs, left fibula

Death of bone tissue in the left fibula (smaller bone in the lower leg) caused by medication side effects, leading to potential bone collapse.

Buddy Insight

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Mapped

HCC 39

Bone/Joint/Muscle Infections/...

RAF 0.401

ACA/HHS

Mapped

HCC 55

HHS-HCC 55

Varies by metal level

ESRD/PACE

Mapped

HCC 39

Bone/Joint/Muscle Infections/...

RAF 0.092

RXHCC

Mapped

HCC 80

Bone/Joint/Muscle Infections/...

RAF 0.204

Code Book Path

Official

M87.1Osteonecrosis due to drugs

M87.16Osteonecrosis due to drugs, tibia and fibula

M87.165Osteonecrosis due to drugs, left fibula

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M87.165 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M87.165 in this effective period.

Related Child Codes

Official

M87.161Osteonecrosis due to drugs, right tibia

M87.162Osteonecrosis due to drugs, left tibia

M87.163Osteonecrosis due to drugs, unspecified tibia

M87.164Osteonecrosis due to drugs, right fibula

M87.166Osteonecrosis due to drugs, unspecified fibula

Includes

Official

ICD-10-CM does not list Includes notes for M87.165 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M87.165 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M87.165 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M87.165 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M87.165 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Clear documentation of left fibula involvement in osteonecrosis

Specific causative medication with exposure timeline

Imaging evidence of left fibular osteonecrosis

Assessment of ankle function and lateral leg stability

MEAT Support

HCC Buddy guidance

Clear documentation of left fibula involvement in osteonecrosis

Specific causative medication with exposure timeline

Imaging evidence of left fibular osteonecrosis

Assessment of ankle function and lateral leg stability

Audit Caution

HCC Buddy guidance

Reversing laterality in left/right fibula documentation

Confusing fibular with tibial involvement in lower leg conditions

Using unspecified codes when laterality is clearly available

Missing drug causation link in complex lower extremity pathology

Common Mistakes

HCC Buddy guidance

M87.162 — Left tibia osteonecrosis affects major weight-bearing bone

M87.164 — Right fibula osteonecrosis, opposite side

M87.166 — Unspecified fibula when left side is documented

M87.265 — Post-traumatic left fibula requires trauma history

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 M87.165 an HCC code?

Yes. M87.165 maps to Bone/Joint/Muscle Infections/Necrosis under the V24 model but is not retained in V28.

Code: M87.165
Description: Osteonecrosis due to drugs, left fibula
HCC (V28): No CMS-HCC V28 mapping
RAF: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

V24HCC 39, Bone/Joint/Muscle Infections/Necrosis

0.401

ESRDHCC 39, Bone/Joint/Muscle Infections/Necrosis

0.092

RxHCCHCC 80, Bone/Joint/Muscle Infections/Necrosis

0.204

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 M87.165 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for M87.165

For M87.165 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 M87.165 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M87.165 is the ICD-10-CM diagnosis code for osteonecrosis due to drugs, left fibula. Death of bone tissue in the left fibula (smaller bone in the lower leg) caused by medication side effects, leading to potential bone collapse. M87.165 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 older CMS-HCC V24 model, M87.165 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.

Confirm left fibula involvement through imaging reports or clinical examination documentation. Because M87.165 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 M87.165 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Confirm left fibula involvement through imaging reports or clinical examination documentation
•Link this diagnosis to the specific medication in the patient's medication history for complete clinical context

Clinical Significance

Drug-induced osteonecrosis of the left fibula involves medication-related bone death in the lateral support bone of the lower leg, potentially affecting ankle stability and overall lower extremity biomechanics. This condition requires orthopedic assessment and management to prevent complications and preserve function.