M05.471 ICD-10-CM Code: Rheumatoid myopathy with rheumatoid arthritis of right ankle and foot
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FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Inflammatory polyarthropathies (M05-M14)
M05.471
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceRheumatoid myopathy with rheumatoid arthritis of right ankle and foot
A condition where rheumatoid arthritis affects the right ankle and foot, causing muscle weakness or damage as a systemic complication.
Buddy Insight
This diagnosis represents rheumatoid arthritis affecting the right ankle and foot with associated myopathy, indicating systemic inflammatory disease with muscle involvement.
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
Official- Rheumatoid myopathy with rheumatoid arthritis, tarsus, metatarsus and phalanges
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M05.471 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M05.471 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M05.471 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M05.471 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M05.471 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M05.471 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 M05.471 an HCC code?
Yes. M05.471 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 M05.471
For M05.471to 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 M05.471 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
M05.471 is the ICD-10-CM diagnosis code for rheumatoid myopathy with rheumatoid arthritis of right ankle and foot. A condition where rheumatoid arthritis affects the right ankle and foot, causing muscle weakness or damage as a systemic complication. M05.471 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, M05.471 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, M05.471 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 documentation clearly indicates RIGHT ankle and foot, not left or bilateral. Because M05.471 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 M05.471 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Ensure documentation clearly indicates RIGHT ankle and foot, not left or bilateral
- •Myopathy component must be documented as related to the rheumatoid arthritis disease process
Clinical Significance
This diagnosis represents rheumatoid arthritis affecting the right ankle and foot with associated myopathy, indicating systemic inflammatory disease with muscle involvement. Ankle and foot RA significantly impacts weight-bearing, balance, and mobility, while myopathy adds treatment complexity.
Documentation Requirements
- ✓Confirmed rheumatoid arthritis diagnosis with established criteria
- ✓Specific documentation of right ankle and foot involvement
- ✓Clinical evidence of myopathy with muscle weakness or dysfunction
- ✓Examination findings demonstrating inflammatory changes in ankle/foot
- ✓Assessment of gait, balance, and weight-bearing capacity
- ✓Documentation of muscle weakness beyond joint limitations
- ✓Comprehensive treatment plan for both conditions
Commonly Confused Codes
- •M05.472: Rheumatoid myopathy with RA of left ankle and foot (different laterality)
- •M05.479: Rheumatoid myopathy with RA of unspecified ankle and foot (when laterality unknown)
- •M06.871: Other specified rheumatoid arthritis, right ankle and foot (lacks myopathy)
- •M19.071: Primary osteoarthritis, right ankle and foot (different arthritis type)
- •G72.9: Myopathy, unspecified (lacks RA component)