M08.462 ICD-10-CM Code: Pauciarticular juvenile rheumatoid arthritis, left knee
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
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 guidancePauciarticular 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
MappedHCC 93
RAF 0.175
CMS-HCC V24
MappedHCC 40
RAF 0.307
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 40
RAF 0.0
RXHCC
MappedHCC 83
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for M08.462 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M08.462 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M08.462 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M08.462 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M08.462 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M08.462 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M08.462 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is M08.462 an HCC code?
Yes. M08.462 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease under the CMS-HCC V28 risk adjustment model (and Rheumatoid Arthritis and Inflammatory Connective Tissue Disease under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.
MEAT Criteria for M08.462
For M08.462to 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.
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 Inflammatory Connective Tissue Disease (HCC 93) with a community, non-dual, aged base RAF weight of 0.175. Under the older V24 model, M08.462 mapped to the same category but with a base RAF weight of 0.307, V28 recalibrated weights across the entire model. 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
Commonly Confused Codes
- •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
- •M17.12: Osteoarthritis left knee versus juvenile arthritis