What is ICD-10 code M87.045?

M87.045 is the ICD-10-CM diagnosis code for Idiopathic aseptic necrosis of left finger(s). Death of bone tissue in the left finger(s) without infection, occurring without a known cause. This condition can lead to pain, loss of function, and potential collapse of the affected bone. M87.045 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M87.045 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. M87.045 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. M87.045 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 M87.045 map to under V28?

M87.045 maps to CMS-HCC V28 92 (Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis). The category number and label come from the CMS-HCC V28 model file for payment year 2026.

What does M87.045 pay in RAF?

M87.045 carries a community, non-dual, aged (CNA) RAF weight of 0.479 under CMS-HCC V28 for payment year 2026. The weight comes from the CMS V28 relative-factor file, not a hand-typed table.

What is the V28 vs V24 difference for M87.045?

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. For M87.045, V28 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis at RAF 0.479 while V24 mapped to Bone/Joint/Muscle Infections/Necrosis at RAF 0.401. Both models can still appear in legacy data and in payer-specific lookback periods.

What documentation supports M87.045?

Verify laterality is documented as left in the medical record before assigning this code Confirm the condition is idiopathic (no identifiable cause) and not secondary to trauma, radiation, or other known factors Because M87.045 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 M87.045: Idiopathic aseptic necrosis

M87.045 maps to CMS-HCC V28 92 (RAF 0.479). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC Buddy coding tools

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Code lookupM87.045Effective 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)

M87.045

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

Idiopathic aseptic necrosis of left finger(s)

Death of bone tissue in the left finger(s) without infection, occurring without a known cause. This condition can lead to pain, loss of function, and potential collapse of the affected bone.

Buddy Insight

Idiopathic aseptic necrosis of left finger(s) involves bone death in phalangeal structures without known cause, potentially severely compromising fine motor function and hand dexterity.

CMS-HCC V28

Mapped

HCC 92

Bone/Joint/Muscle/Severe Soft...

RAF 0.479

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

M87.0Idiopathic aseptic necrosis of bone

M87.04Idiopathic aseptic necrosis of hand and fingers

M87.045Idiopathic aseptic necrosis of left finger(s)

Inclusion Terms

Official

Idiopathic aseptic necrosis of metacarpals and phalanges of hands

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M87.045 in this effective period.

Related Child Codes

Official

M87.041Idiopathic aseptic necrosis of right hand

M87.042Idiopathic aseptic necrosis of left hand

M87.043Idiopathic aseptic necrosis of unspecified hand

M87.044Idiopathic aseptic necrosis of right finger(s)

M87.046Idiopathic aseptic necrosis of unspecified finger(s)

Includes

Official

ICD-10-CM does not list Includes notes for M87.045 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M87.045 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M87.045 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M87.045 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M87.045 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Clear documentation of aseptic necrosis involving left finger bones

Confirmation of idiopathic nature without identifiable underlying cause

Radiological evidence showing bone necrosis in left finger phalanges

Specific laterality documentation indicating left finger involvement

MEAT Support

HCC Buddy guidance

Clear documentation of aseptic necrosis involving left finger bones

Confirmation of idiopathic nature without identifiable underlying cause

Radiological evidence showing bone necrosis in left finger phalanges

Specific laterality documentation indicating left finger involvement

Audit Caution

HCC Buddy guidance

Reversing laterality when documentation specifies left fingers

Defaulting to unspecified when laterality is explicitly documented

Confusing finger necrosis with hand necrosis codes

Missing drug-induced causes requiring M87.145 code assignment

Common Mistakes

HCC Buddy guidance

M87.044 — Right finger(s) when laterality is incorrectly assigned

M87.046 — Unspecified finger(s) when left side is documented

M87.145 — Drug-induced left finger osteonecrosis

M87.245 — Trauma-related left finger osteonecrosis

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 M87.045 an HCC code?

Yes. M87.045 (Idiopathic aseptic necrosis of left finger(s)) 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: M87.045 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: M87.045
Description: Idiopathic aseptic necrosis of left finger(s)
HCC (V28): HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
RAF: 0.479
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis

0.479

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 M87.045 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for M87.045

For M87.045 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 M87.045 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M87.045 is the ICD-10-CM diagnosis code for idiopathic aseptic necrosis of left finger(s). Death of bone tissue in the left finger(s) without infection, occurring without a known cause. This condition can lead to pain, loss of function, and potential collapse of the affected bone. M87.045 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, M87.045 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, M87.045 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 M87.045 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 M87.045 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
•Confirm the condition is idiopathic (no identifiable cause) and not secondary to trauma, radiation, or other known factors

Clinical Significance

Idiopathic aseptic necrosis of left finger(s) involves bone death in phalangeal structures without known cause, potentially severely compromising fine motor function and hand dexterity. This condition can lead to pain, loss of function, and potential collapse of the affected bone requiring specialized hand surgery management.