M05.071 ICD-10-CM Code: Felty's syndrome, 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)
M05.071
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceFelty's syndrome, right ankle and foot
Felty's syndrome affecting the right ankle and foot, a condition combining rheumatoid arthritis with an enlarged spleen and low white blood cell count.
Buddy Insight
Felty's syndrome affecting the right ankle and foot represents a severe rheumatoid condition that significantly impairs mobility and creates dangerous immunosuppression through neutropenia and splenomegaly.
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- Felty's syndrome, tarsus, metatarsus and phalanges
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M05.071 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M05.071 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M05.071 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M05.071 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M05.071 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M05.071 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 M05.071 an HCC code?
Yes. M05.071 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 M05.071
For M05.071to 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 M05.071 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
M05.071 is the ICD-10-CM diagnosis code for felty's syndrome, right ankle and foot. Felty's syndrome affecting the right ankle and foot, a condition combining rheumatoid arthritis with an enlarged spleen and low white blood cell count. M05.071 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, M05.071 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, M05.071 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.
Felty's syndrome is a specific manifestation of rheumatoid arthritis; ensure the diagnosis documentation clearly states Felty's syndrome rather than just RA. Because M05.071 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 M05.071 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Felty's syndrome is a specific manifestation of rheumatoid arthritis; ensure the diagnosis documentation clearly states Felty's syndrome rather than just RA
- •The seventh character specifies laterality (right ankle/foot); verify documentation confirms right-sided involvement
Clinical Significance
Felty's syndrome affecting the right ankle and foot represents a severe rheumatoid condition that significantly impairs mobility and creates dangerous immunosuppression through neutropenia and splenomegaly. Lower extremity involvement severely compromises ambulation while the hematologic abnormalities require intensive monitoring for life-threatening complications.
Documentation Requirements
- ✓Specific documentation of rheumatoid arthritis affecting right ankle and foot
- ✓Clinical or imaging evidence of splenomegaly
- ✓Laboratory confirmation of neutropenia with quantitative cell counts
- ✓Right ankle and foot involvement with clear laterality specification
- ✓Assessment of weight-bearing function and ambulatory capacity
- ✓Evaluation of infection history and immune status
- ✓Current disease-modifying therapy and monitoring protocols
- ✓Podiatry consultation and orthotic needs documentation
Commonly Confused Codes
- •M05.072: Same condition but affecting left ankle and foot instead of right
- •M05.9: Seropositive rheumatoid arthritis without Felty's syndrome components
- •M19.071: Primary osteoarthritis of right ankle and foot without inflammatory basis
- •D70.9: Neutropenia without rheumatoid arthritis context
- •M25.571: Pain in right ankle and foot without systemic components