What is ICD-10 code M08.462?

M08.462 is the ICD-10-CM diagnosis code for Pauciarticular juvenile rheumatoid arthritis, left knee. A type of childhood arthritis affecting only a few joints, specifically involving the left knee. This causes inflammation and can affect the child's ability to walk and move. M08.462 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M08.462 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. M08.462 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. M08.462 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 M08.462 map to under V28?

M08.462 maps to CMS-HCC V28 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders). The category number and label come from the CMS-HCC V28 model file for payment year 2026.

What does M08.462 pay in RAF?

M08.462 carries a community, non-dual, aged (CNA) RAF weight of 0.617 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 M08.462?

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 M08.462, V28 maps to Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders at RAF 0.617 while V24 mapped to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease at RAF 0.421. Both models can still appear in legacy data and in payer-specific lookback periods.

2026 ICD-10-CM M08.462: Pauciarticular juvenile

M08.462 maps to CMS-HCC V28 93 (RAF 0.617). Documentation must support MEAT. MEAT criteria · RAF calculator · free HCC coding tools

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Code lookupM08.462Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Inflammatory polyarthropathies (M05-M14)

M08.462

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

Pauciarticular juvenile rheumatoid arthritis, left knee

A type of childhood arthritis affecting only a few joints, specifically involving the left knee. This causes inflammation and can affect the child's ability to walk and move.

Buddy Insight

Pauciarticular juvenile rheumatoid arthritis of the left knee is a chronic inflammatory condition that can significantly impact a child's mobility, growth, and quality of life.

CMS-HCC V28

Mapped

HCC 93

Rheumatoid Arthritis and Othe...

RAF 0.617

CMS-HCC V24

Mapped

HCC 40

Rheumatoid Arthritis and Infl...

RAF 0.421

ACA/HHS

Mapped

HCC 56

HHS-HCC 56

Varies by metal level

ESRD/PACE

Mapped

HCC 40

Rheumatoid Arthritis and Infl...

RAF 0.058

RXHCC

Mapped

HCC 83

Rheumatoid Arthritis and Infl...

RAF 0.222

Code Book Path

Official

M08.4Pauciarticular juvenile rheumatoid arthritis

M08.46Pauciarticular juvenile rheumatoid arthritis, knee

M08.462Pauciarticular juvenile rheumatoid arthritis, left knee

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M08.462 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M08.462 in this effective period.

Related Child Codes

Official

M08.461Pauciarticular juvenile rheumatoid arthritis, right knee

M08.469Pauciarticular juvenile rheumatoid arthritis, unspecified knee

Includes

Official

ICD-10-CM does not list Includes notes for M08.462 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M08.462 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M08.462 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M08.462 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M08.462 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Physician diagnosis of juvenile rheumatoid arthritis with pauciarticular involvement

Clear documentation of left knee joint affected

Evidence of inflammatory joint changes (swelling, warmth, effusion)

Age at onset documentation confirming pediatric presentation

MEAT Support

HCC Buddy guidance

Physician diagnosis of juvenile rheumatoid arthritis with pauciarticular involvement

Clear documentation of left knee joint affected

Evidence of inflammatory joint changes (swelling, warmth, effusion)

Age at onset documentation confirming pediatric presentation

Audit Caution

HCC Buddy guidance

Laterality errors when coding left versus right knee involvement

Using unspecified codes when specific joint documentation exists

Misclassification of juvenile arthritis subtypes

Coding symptoms instead of the underlying inflammatory diagnosis

Common Mistakes

HCC Buddy guidance

M08.461 — Right knee versus left knee involvement

M08.469 — Unspecified knee versus specifically documented left knee

M08.40 — Unspecified site versus documented knee involvement

M25.562 — Left knee pain versus established inflammatory arthritis

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 M08.462 an HCC code?

Yes. M08.462 (Pauciarticular juvenile rheumatoid arthritis, left knee) maps to Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders under the CMS-HCC V28 risk adjustment model (and Rheumatoid Arthritis and Inflammatory Connective Tissue Disease under V24), with a community non-dual aged RAF of 0.617. It is billable for payment year 2026.

Coder answer: M08.462 is billable and maps to V28 HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: M08.462
Description: Pauciarticular juvenile rheumatoid arthritis, left knee
HCC (V28): HCC 93 — Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders
RAF: 0.617
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders

0.617

V24HCC 40, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease

0.421

ESRDHCC 40, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease

0.058

RxHCCHCC 83, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease

0.222

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 M08.462 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for M08.462

For M08.462 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 M08.462 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M08.462 is the ICD-10-CM diagnosis code for pauciarticular juvenile rheumatoid arthritis, left knee. A type of childhood arthritis affecting only a few joints, specifically involving the left knee. This causes inflammation and can affect the child's ability to walk and move. M08.462 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering inflammatory polyarthropathies (m05-m14).

Under the CMS-HCC V28 risk adjustment model, M08.462 maps to Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders (HCC 93) with a community, non-dual, aged base RAF weight of 0.617. Under the older CMS-HCC V24 model, M08.462 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease (HCC 40) with a community, non-dual, aged base RAF weight of 0.421. 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.

Confirm left knee is the documented affected site. Because M08.462 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 M08.462 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Confirm left knee is the documented affected site
•Document any associated gait disturbance or functional impairment related to knee involvement

Clinical Significance

Pauciarticular juvenile rheumatoid arthritis of the left knee is a chronic inflammatory condition that can significantly impact a child's mobility, growth, and quality of life. Early recognition and appropriate treatment are essential to prevent joint destruction, leg length discrepancies, and functional limitations that may persist into adulthood.

Documentation Requirements

✓Physician diagnosis of juvenile rheumatoid arthritis with pauciarticular involvement
✓Clear documentation of left knee joint affected
✓Evidence of inflammatory joint changes (swelling, warmth, effusion)
✓Age at onset documentation confirming pediatric presentation
✓Supporting laboratory studies including inflammatory markers
✓Imaging studies documenting joint involvement when available
✓Functional impact assessment on walking and activities
✓Comprehensive treatment plan including physical therapy