M08.461 ICD-10-CM Code: Pauciarticular juvenile rheumatoid arthritis, right knee
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FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Inflammatory polyarthropathies (M05-M14)
M08.461
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidancePauciarticular juvenile rheumatoid arthritis, right knee
A type of childhood arthritis affecting only a few joints, specifically involving the right knee. This causes inflammation and can affect the child's ability to walk and move.
Buddy Insight
Pauciarticular juvenile rheumatoid arthritis affecting the right knee represents a significant pediatric rheumatologic condition with potential for serious long-term complications.
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
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Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for M08.461 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M08.461 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M08.461 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M08.461 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M08.461 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M08.461 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M08.461 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 M08.461 an HCC code?
Yes. M08.461 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 M08.461
For M08.461to 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 M08.461 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
M08.461 is the ICD-10-CM diagnosis code for pauciarticular juvenile rheumatoid arthritis, right knee. A type of childhood arthritis affecting only a few joints, specifically involving the right knee. This causes inflammation and can affect the child's ability to walk and move. M08.461 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, M08.461 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, M08.461 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.
Ensure right knee is clearly documented as the affected site. Because M08.461 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 M08.461 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Ensure right knee is clearly documented as the affected site
- •Knee involvement often requires documentation of functional limitations and mobility status
Clinical Significance
Pauciarticular juvenile rheumatoid arthritis affecting the right knee represents a significant pediatric rheumatologic condition with potential for serious long-term complications. Knee involvement can severely impact a child's mobility, participation in activities, and normal development, requiring coordinated care to prevent joint damage and maintain function throughout growth periods.
Documentation Requirements
- ✓Confirmed diagnosis of juvenile rheumatoid arthritis with pauciarticular pattern
- ✓Specific documentation of right knee joint involvement
- ✓Clinical signs of joint inflammation and stiffness
- ✓Pediatric age at onset (typically under 16 years)
- ✓Inflammatory laboratory markers and rheumatologic studies
- ✓Functional assessment including mobility and activity limitations
- ✓Treatment plan with anti-inflammatory and disease-modifying therapies
- ✓Monitoring for growth disturbances and joint complications
Commonly Confused Codes
- •M08.462: Left knee versus right knee involvement
- •M08.469: Unspecified knee versus documented right knee
- •M08.40: Pauciarticular JRA unspecified site versus specific knee involvement
- •M25.561: Pain in right knee versus inflammatory arthritis
- •M17.11: Osteoarthritis right knee versus juvenile inflammatory disease