What is ICD-10 code M87.849?

M87.849 is the ICD-10-CM diagnosis code for Other osteonecrosis, unspecified finger(s). Death of bone tissue in finger(s) when the specific hand (left or right) is not documented or cannot be determined. It belongs to the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99). M87.849 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M87.849 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. M87.849 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. M87.849 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.

What is the V28 vs V24 difference for M87.849?

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 M87.849, 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 should coders know when reporting M87.849?

Use only when laterality is truly unspecified; query provider for clarification when possible Review imaging reports which may indicate side-specific involvement Because M87.849 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.

2026 ICD-10-CM M87.849: Other osteonecrosis

ICD-10-CM Code View

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Code lookupM87.849Effective 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)

M87.849

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

Other osteonecrosis, unspecified finger(s)

Death of bone tissue in finger(s) when the specific hand (left or right) is not documented or cannot be determined.

Buddy Insight

Unspecified finger osteonecrosis represents a chronic bone condition with potential for functional disability and ongoing care requirements.

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

M87.8Other osteonecrosis

M87.84Other osteonecrosis, hand and fingers

M87.849Other osteonecrosis, unspecified finger(s)

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M87.849 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M87.849 in this effective period.

Related Child Codes

Official

M87.841Other osteonecrosis, right hand

M87.842Other osteonecrosis, left hand

M87.843Other osteonecrosis, unspecified hand

M87.844Other osteonecrosis, right finger(s)

M87.845Other osteonecrosis, left finger(s)

Includes

Official

ICD-10-CM does not list Includes notes for M87.849 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M87.849 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M87.849 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M87.849 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M87.849 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of osteonecrosis affecting finger bones (phalanges)

Specification that the condition is from causes other than idiopathic or traumatic

Evidence that laterality (right or left) is not specified or cannot be determined

Imaging studies confirming bone necrosis in finger structures

MEAT Support

HCC Buddy guidance

Documentation of osteonecrosis affecting finger bones (phalanges)

Specification that the condition is from causes other than idiopathic or traumatic

Evidence that laterality (right or left) is not specified or cannot be determined

Imaging studies confirming bone necrosis in finger structures

Audit Caution

HCC Buddy guidance

Using this code when laterality is actually specified in medical records

Confusing with idiopathic osteonecrosis when cause is documented as 'other'

Failing to distinguish between osteonecrosis and osteomyelitis

Coding traumatic injuries when dealing with chronic bone death

Common Mistakes

HCC Buddy guidance

M87.049 — Idiopathic aseptic necrosis of unspecified finger(s) - specifically idiopathic cause

M87.844/M87.845 — Other osteonecrosis of right/left finger(s) - when laterality is actually documented

M86.849 — Other osteomyelitis, unspecified finger(s) - infectious condition rather than necrosis

S62.609A — Fracture of unspecified phalanx of unspecified finger - acute trauma rather than chronic condition

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 M87.849 an HCC code?

Yes. M87.849 (Other osteonecrosis, unspecified 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: M87.849 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: M87.849
Description: Other osteonecrosis, unspecified 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 M87.849 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for M87.849

For M87.849 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 M87.849 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M87.849 is the ICD-10-CM diagnosis code for other osteonecrosis, unspecified finger(s). Death of bone tissue in finger(s) when the specific hand (left or right) is not documented or cannot be determined. M87.849 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, M87.849 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, M87.849 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.

Use only when laterality is truly unspecified; query provider for clarification when possible. Because M87.849 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 M87.849 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use only when laterality is truly unspecified; query provider for clarification when possible
•Review imaging reports which may indicate side-specific involvement

Clinical Significance

Unspecified finger osteonecrosis represents a chronic bone condition with potential for functional disability and ongoing care requirements. This diagnosis is significant for risk adjustment as it indicates complex orthopedic management needs and potential requirement for specialized interventions.

Documentation Requirements

✓Documentation of osteonecrosis affecting finger bones (phalanges)
✓Specification that the condition is from causes other than idiopathic or traumatic
✓Evidence that laterality (right or left) is not specified or cannot be determined
✓Imaging studies confirming bone necrosis in finger structures
✓Clinical symptoms including finger pain, stiffness, and functional impairment
✓Exclusion of infectious or drug-induced causes
✓Assessment of impact on hand function and activities of daily living
✓Provider documentation of treatment approach and monitoring needs

Commonly Confused Codes

•M87.049: Idiopathic aseptic necrosis of unspecified finger(s) - specifically idiopathic cause
•M87.844/M87.845: Other osteonecrosis of right/left finger(s) - when laterality is actually documented
•M86.849: Other osteomyelitis, unspecified finger(s) - infectious condition rather than necrosis
•S62.609A: Fracture of unspecified phalanx of unspecified finger - acute trauma rather than chronic condition
•M20.019: Mallet finger of unspecified finger(s) - tendon injury rather than bone necrosis