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M05.059 ICD-10-CM Code: Felty's syndrome, unspecified hip

M05.059 maps to CMS-HCC V28 93 (RAF 0.617). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC coding software

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

M05.059

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

Felty's syndrome, unspecified hip

Felty's syndrome affecting the hip when the specific hip (right or left) is not identified.

Buddy the Bee presenting code insight

Buddy Insight

Felty's syndrome with unspecified hip involvement indicates the presence of the complete diagnostic triad affecting hip function without documented laterality.

CMS-HCC V28

HCC 93

RAF 0.617

CMS-HCC V24

HCC 40

RAF 0.421

ACA/HHS

HCC 56

Varies by metal level

ESRD/PACE

HCC 40

RAF 0.058

RXHCC

HCC 83

RAF 0.222

Code Book Path

Official
M05.0Felty's syndrome
M05.05Felty's syndrome, hip
M05.059Felty's syndrome, unspecified hip

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M05.059 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M05.059 in this effective period.

Related Child Codes

Official
M05.051Felty's syndrome, right hip
M05.052Felty's syndrome, left hip

Includes

Official

ICD-10-CM does not list Includes notes for M05.059 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M05.059 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M05.059 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M05.059 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M05.059 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Documentation of rheumatoid arthritis affecting hip without laterality specification
Clinical or imaging evidence of splenomegaly
Laboratory documentation of neutropenia with quantitative values
Hip joint involvement noted but side not specified

MEAT Support

HCC Buddy guidance
Documentation of rheumatoid arthritis affecting hip without laterality specification
Clinical or imaging evidence of splenomegaly
Laboratory documentation of neutropenia with quantitative values
Hip joint involvement noted but side not specified

Audit Caution

HCC Buddy guidance
Using unspecified code when laterality is documented elsewhere in the record
Confusing with osteoarthritis rather than inflammatory rheumatoid condition
Failing to verify presence of all three Felty's syndrome components
Missing opportunities for more specific coding when side is mentioned

Common Mistakes

HCC Buddy guidance
M05.051 or M05.052 — When hip laterality is actually documented in records
M05.9 — Rheumatoid arthritis seropositive without the complete syndrome
M16.9 — Osteoarthritis of hip unspecified without inflammatory component
D70.9 — Neutropenia without associated rheumatoid 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 M05.059 an HCC code?

Yes. M05.059 (Felty's syndrome, unspecified hip) 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: M05.059 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
M05.059
Description
Felty's syndrome, unspecified hip
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 M05.059 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for M05.059

For M05.059 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 M05.059 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M05.059 is the ICD-10-CM diagnosis code for felty's syndrome, unspecified hip. Felty's syndrome affecting the hip when the specific hip (right or left) is not identified. M05.059 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, M05.059 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, M05.059 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.

Use only when hip involvement is documented but laterality is unclear; attempt to clarify with provider. Because M05.059 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 M05.059 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Use only when hip involvement is documented but laterality is unclear; attempt to clarify with provider
  • •This unspecified code should be avoided when possible in favor of laterality-specific codes

Clinical Significance

Felty's syndrome with unspecified hip involvement indicates the presence of the complete diagnostic triad affecting hip function without documented laterality. This severe condition creates significant mobility challenges combined with life-threatening immunosuppression requiring comprehensive multidisciplinary care coordination and intensive monitoring protocols.

Documentation Requirements

  • ✓Documentation of rheumatoid arthritis affecting hip without laterality specification
  • ✓Clinical or imaging evidence of splenomegaly
  • ✓Laboratory documentation of neutropenia with quantitative values
  • ✓Hip joint involvement noted but side not specified
  • ✓Assessment of mobility and weight-bearing function
  • ✓Evaluation of immune status and infection complications
  • ✓Treatment protocol addressing all syndrome components
  • ✓Physical therapy and mobility assistance needs assessment

Commonly Confused Codes

  • •M05.051 or M05.052: When hip laterality is actually documented in records
  • •M05.9: Rheumatoid arthritis seropositive without the complete syndrome
  • •M16.9: Osteoarthritis of hip unspecified without inflammatory component
  • •D70.9: Neutropenia without associated rheumatoid arthritis
  • •M06.9: Rheumatoid arthritis unspecified without hematologic involvement

Child Codes

M05.051Felty's syndrome, right hip
HCC 93
M05.052Felty's syndrome, left hip
HCC 93
M05.059Felty's syndrome, unspecified hip
HCC 93

Code Hierarchy

└M05Rheumatoid arthritis with rheumatoid factor└M05.0Felty's syndrome└M05.05Felty's syndrome, hip└M05.059Felty's syndrome, unspecified hip
└M05.059Felty's syndrome, unspecified hip

Because M05.059 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

M05.059 maps to CMS-HCC V28 category 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. Because M05.059 carries a payment HCC, you can see what it adds to a RAF score and check the documentation the chart needs before it is submitted.

More on M05.059

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