What is ICD-10 code M86.471?

M86.471 is the ICD-10-CM diagnosis code for Chronic osteomyelitis with draining sinus, right ankle and foot. A chronic bone infection of the right ankle and foot bones that has created an open drainage channel through the skin, allowing infected material to drain continuously. M86.471 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M86.471 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. M86.471 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. M86.471 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 M86.471 map to under V28?

M86.471 maps to CMS-HCC V28 HCC 92 (Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM M86.471: Chronic osteomyelitis

M86.471 maps to CMS-HCC V28 92. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · free HCC coding tools

ICD-10-CM Code View

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Code lookupM86.471Effective 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)

M86.471

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

Chronic osteomyelitis with draining sinus, right ankle and foot

A chronic bone infection of the right ankle and foot bones that has created an open drainage channel through the skin, allowing infected material to drain continuously.

Buddy Insight

CMS-HCC V28

Mapped

HCC 92

Bone/Joint/Muscle/Severe Soft...

Code-level coefficient reference

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

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

M86.4Chronic osteomyelitis with draining sinus

M86.47Chronic osteomyelitis with draining sinus, ankle and foot

M86.471Chronic osteomyelitis with draining sinus, right ankle and foot

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M86.471 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M86.471 in this effective period.

Related Child Codes

Official

M86.472Chronic osteomyelitis with draining sinus, left ankle and foot

M86.479Chronic osteomyelitis with draining sinus, unspecified ankle and foot

Includes

Official

ICD-10-CM does not list Includes notes for M86.471 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M86.471 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M86.471 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M86.471 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M86.471 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of chronic osteomyelitis diagnosis

Clear evidence of draining sinus tract with ongoing drainage

Specific identification of right ankle and foot involvement

Detailed description of sinus tract location and drainage

MEAT Support

HCC Buddy guidance

Documentation of chronic osteomyelitis diagnosis

Clear evidence of draining sinus tract with ongoing drainage

Specific identification of right ankle and foot involvement

Detailed description of sinus tract location and drainage

Audit Caution

HCC Buddy guidance

Confusing laterality when coding ankle and foot involvement

Missing the draining sinus component during code selection

Separating ankle and foot when both are involved

Using unspecified codes when specific anatomy is documented

Common Mistakes

HCC Buddy guidance

M86.472 — Chronic osteomyelitis with draining sinus, left ankle and foot (wrong laterality)

M86.671 — Other chronic osteomyelitis, right ankle and foot (no draining sinus)

M86.571 — Other chronic hematogenous osteomyelitis, right ankle and foot (different type)

M86.461 — Chronic osteomyelitis with draining sinus, right tibia and fibula (different bones)

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 M86.471 an HCC code?

Yes. M86.471 (Chronic osteomyelitis with draining sinus, right ankle and foot) maps to HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.479. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: M86.471 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: M86.471
Description: Chronic osteomyelitis with draining sinus, right ankle and foot
HCC (V28): HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
RAF reference coefficient: 0.479
Billable: Yes
Payment year: 2026

HCC Category Mapping

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

0.479

ESRDHCC 39, Bone/Joint/Muscle Infections/Necrosis

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 M86.471 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for M86.471

For M86.471 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 M86.471 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M86.471 is the ICD-10-CM diagnosis code for chronic osteomyelitis with draining sinus, right ankle and foot. A chronic bone infection of the right ankle and foot bones that has created an open drainage channel through the skin, allowing infected material to drain continuously. M86.471 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, M86.471 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis (HCC 92) with a source-labeled community, non-dual, aged reference coefficient of 0.479. No V24 mapping is shown for M86.471; use the applicable model and payment year when reviewing the V28 mapping. 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. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Verify laterality is documented as 'right' in the medical record before assigning this code. Because M86.471 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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, source-labeled coefficient references, and MEAT documentation criteria for M86.471 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 'right' in the medical record before assigning this code
•This code applies to chronic osteomyelitis affecting any bones in the right ankle and foot region

Clinical Significance

Chronic osteomyelitis with draining sinus of the right ankle and foot represents a severe, complicated bone infection with persistent drainage that significantly impacts mobility and weight-bearing function. This condition requires intensive treatment including prolonged antibiotics, surgical debridement, and specialized wound care, substantially affecting patient quality of life and functional capacity.

Documentation Requirements

✓Documentation of chronic osteomyelitis diagnosis
✓Clear evidence of draining sinus tract with ongoing drainage
✓Specific identification of right ankle and foot involvement
✓Detailed description of sinus tract location and drainage
✓Microbiological studies and culture results
✓Imaging studies demonstrating infection and sinus pathway
✓Treatment history including antibiotic therapy and surgical interventions
✓Assessment of ambulation status and functional limitations

Commonly Confused Codes

•M86.472: Chronic osteomyelitis with draining sinus, left ankle and foot (wrong laterality)
•M86.671: Other chronic osteomyelitis, right ankle and foot (no draining sinus)
•M86.571: Other chronic hematogenous osteomyelitis, right ankle and foot (different type)
•M86.461: Chronic osteomyelitis with draining sinus, right tibia and fibula (different bones)