What is ICD-10 code M87.171?

M87.171 is the ICD-10-CM diagnosis code for Osteonecrosis due to drugs, right ankle. Death of bone tissue in the right ankle caused by medication side effects, potentially affecting mobility and joint function. M87.171 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M87.171 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. M87.171 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. M87.171 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 M87.171 map to under V28?

M87.171 has no payable CMS-HCC V28 mapping in the final FY2026 CMS file.

What RAF reference is published for M87.171?

M87.171 has no V28 reference coefficient because the final FY2026 source verifies no payable V28 mapping.

What is the V28 vs V24 difference for M87.171?

M87.171 has verified no payable V28 mapping in the final FY2026 source. Select a historical effective period before making any V24 comparison.

What documentation supports M87.171?

Verify whether the osteonecrosis affects the talus or other ankle bones and document accordingly Correlate with imaging findings to confirm drug-induced etiology versus other causes M87.171 is not a CMS-HCC V28 payment code in the verified current source, so MEAT is not the payment hook. Documentation still has to support the diagnosis if you report it.

2026 ICD-10-CM M87.171: Osteonecrosis due to drugs, right

M87.171 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 lookupM87.171Effective 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)

M87.171

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

Osteonecrosis due to drugs, right ankle

Death of bone tissue in the right ankle caused by medication side effects, potentially affecting mobility and joint function.

Buddy Insight

Drug-induced osteonecrosis of the right ankle involves medication-related bone death affecting the complex joint structure, potentially compromising mobility and weight-bearing capacity.

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 055

HHS-HCC 055 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 39

Bone/Joint/Muscle Infections/...

Code-level coefficient reference

RXHCC

Mapped

HCC 80

Aseptic Necrosis of Bone

Code-level coefficient reference

Code Book Path

Official

M87.1Osteonecrosis due to drugs

M87.17Osteonecrosis due to drugs, ankle, foot and toes

M87.171Osteonecrosis due to drugs, right ankle

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M87.171 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M87.171 in this effective period.

Related Child Codes

Official

M87.172Osteonecrosis due to drugs, left ankle

M87.173Osteonecrosis due to drugs, unspecified ankle

M87.174Osteonecrosis due to drugs, right foot

M87.175Osteonecrosis due to drugs, left foot

M87.176Osteonecrosis due to drugs, unspecified foot

Includes

Official

ICD-10-CM does not list Includes notes for M87.171 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M87.171 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M87.171 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M87.171 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M87.171 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Specific documentation of right ankle involvement in osteonecrosis

Causative medication identification with exposure details

Advanced imaging confirming ankle osteonecrosis

Assessment of ankle joint function and range of motion

MEAT Support

HCC Buddy guidance

Specific documentation of right ankle involvement in osteonecrosis

Causative medication identification with exposure details

Advanced imaging confirming ankle osteonecrosis

Assessment of ankle joint function and range of motion

Audit Caution

HCC Buddy guidance

Confusing ankle joint with broader foot involvement

Using unspecified laterality when right side is clearly documented

Missing drug causation in patients with multiple ankle problems

Using acute injury codes for chronic drug-induced conditions

Common Mistakes

HCC Buddy guidance

M87.172 — Left ankle osteonecrosis, opposite laterality

M87.173 — Unspecified ankle when right side is documented

M87.174 — Right foot osteonecrosis involves broader foot structures

M87.271 — Post-traumatic right ankle requires injury 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 M87.171 an HCC code?

M87.171 is not in the CMS-HCC V28 or V24 community payment model. M87.171 has a separate mapping under the CMS-HCC ESRD model (HCC 39 (Bone/Joint/Muscle Infections/Necrosis)) and the Part D RxHCC model (HCC 80 (Aseptic Necrosis of Bone)); the applicable result needs member context. M87.171 also appears in the HHS-HCC commercial risk model (HCC 055 (HHS-HCC 055 adult, RAF varies by metal level)), which is a commercial market model rather than a Medicare Advantage payment mapping.

Code: M87.171
Description: Osteonecrosis due to drugs, right ankle
HCC (V28): No CMS-HCC V28 mapping
RAF reference coefficient: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

ESRDHCC 39, Bone/Joint/Muscle Infections/Necrosis

Not separately weighted

RxHCCHCC 80, Aseptic Necrosis of Bone

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work M87.171 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for M87.171

For M87.171 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 M87.171 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M87.171 is the ICD-10-CM diagnosis code for osteonecrosis due to drugs, right ankle. Death of bone tissue in the right ankle caused by medication side effects, potentially affecting mobility and joint function. M87.171 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).

M87.171 has no mapping under the CMS-HCC V28 or V24 community payment models. M87.171 has a separate mapping under the CMS-HCC ESRD model (HCC 39 (Bone/Joint/Muscle Infections/Necrosis)) and the Part D RxHCC model (HCC 80 (Aseptic Necrosis of Bone)); the applicable result needs member context. M87.171 also appears in the HHS-HCC commercial risk model (HCC 055 (HHS-HCC 055 adult, RAF varies by metal level)), which is a commercial market model rather than a Medicare Advantage payment mapping. Do not assign V28 risk adjustment value from this page; verify the applicable model and payment year before using this code for risk adjustment.

Verify whether the osteonecrosis affects the talus or other ankle bones and document accordingly.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for M87.171 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Verify whether the osteonecrosis affects the talus or other ankle bones and document accordingly
•Correlate with imaging findings to confirm drug-induced etiology versus other causes

Clinical Significance

Drug-induced osteonecrosis of the right ankle involves medication-related bone death affecting the complex joint structure, potentially compromising mobility and weight-bearing capacity. This condition may require specialized orthopedic intervention and can significantly impact daily activities and ambulation.