What is ICD-10 code M87.134?

M87.134 is the ICD-10-CM diagnosis code for Osteonecrosis due to drugs of right ulna. Death of bone tissue in the right ulna (forearm bone on the pinky side) caused by medication side effects. M87.134 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M87.134 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. M87.134 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. M87.134 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 M87.134?

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. M87.134 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 should coders know when reporting M87.134?

Distinguish between radius and ulna carefully; both are forearm bones but in different locations Confirm right side documentation and the causative medication in the medical record Because M87.134 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 M87.134: Osteonecrosis due to drugs

ICD-10-CM Code View

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Code lookupM87.134Effective 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)

M87.134

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

Osteonecrosis due to drugs of right ulna

Death of bone tissue in the right ulna (forearm bone on the pinky side) caused by medication side effects.

Buddy Insight

Drug-induced osteonecrosis of the right ulna affects the medial forearm bone, potentially compromising elbow stability and wrist function.

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

M87.13Osteonecrosis due to drugs of radius, ulna and carpus

M87.134Osteonecrosis due to drugs of right ulna

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M87.134 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M87.134 in this effective period.

Related Child Codes

Official

M87.131Osteonecrosis due to drugs of right radius

M87.132Osteonecrosis due to drugs of left radius

M87.133Osteonecrosis due to drugs of unspecified radius

M87.135Osteonecrosis due to drugs of left ulna

M87.136Osteonecrosis due to drugs of unspecified ulna

Includes

Official

ICD-10-CM does not list Includes notes for M87.134 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M87.134 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M87.134 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M87.134 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M87.134 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Specific identification of right ulna as the affected bone

Causative medication documentation with exposure details

Radiologic evidence of ulnar osteonecrosis (MRI, CT, or bone scan)

Clinical symptoms including localized pain and functional deficits

MEAT Support

HCC Buddy guidance

Specific identification of right ulna as the affected bone

Causative medication documentation with exposure details

Radiologic evidence of ulnar osteonecrosis (MRI, CT, or bone scan)

Clinical symptoms including localized pain and functional deficits

Audit Caution

HCC Buddy guidance

Confusing ulna and radius anatomy in forearm osteonecrosis

Using unspecified laterality when right side is documented

Missing drug causation documentation in complex cases

Conflating acute ulnar injury with chronic drug-induced necrosis

Common Mistakes

HCC Buddy guidance

M87.131 — Right radius osteonecrosis affects different forearm bone

M87.136 — Use when ulna laterality is not specified

M87.234 — Post-traumatic right ulna requires injury history documentation

M87.034 — Idiopathic osteonecrosis lacks drug causation

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 M87.134 an HCC code?

Yes. M87.134 maps to Bone/Joint/Muscle Infections/Necrosis under the V24 model but is not retained in V28.

Code: M87.134
Description: Osteonecrosis due to drugs of right ulna
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 M87.134 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for M87.134

For M87.134 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 M87.134 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M87.134 is the ICD-10-CM diagnosis code for osteonecrosis due to drugs of right ulna. Death of bone tissue in the right ulna (forearm bone on the pinky side) caused by medication side effects. M87.134 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, M87.134 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.

Distinguish between radius and ulna carefully; both are forearm bones but in different locations. Because M87.134 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 M87.134 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Distinguish between radius and ulna carefully; both are forearm bones but in different locations
•Confirm right side documentation and the causative medication in the medical record

Clinical Significance

Drug-induced osteonecrosis of the right ulna affects the medial forearm bone, potentially compromising elbow stability and wrist function. This condition requires careful monitoring as ulnar involvement can impact both proximal and distal joint mechanics in the affected extremity.