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M08.021 ICD-10-CM Code: Unspecified juvenile rheumatoid arthritis, right elbow

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

M08.021

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

Unspecified juvenile rheumatoid arthritis, right elbow

Juvenile rheumatoid arthritis affecting the right elbow in a child, where the specific type of juvenile arthritis has not been determined.

Buddy the Bee presenting code insight

Buddy Insight

Juvenile rheumatoid arthritis affecting the right elbow represents a chronic inflammatory condition with potential for growth disturbances and functional impairment.

CMS-HCC V28

HCC 93

RAF 0.175

CMS-HCC V24

HCC 40

RAF 0.307

ACA/HHS

0

0

RAF 0

ESRD/PACE

HCC 40

RAF 0.0

RXHCC

HCC 83

RAF 0.0

Code Trumping

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Code Book Path

Official
M08.0Unspecified juvenile rheumatoid arthritis
M08.02Unspecified juvenile rheumatoid arthritis of elbow
M08.021Unspecified juvenile rheumatoid arthritis, right elbow

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M08.021 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M08.021 in this effective period.

Related Child Codes

Official
M08.022Unspecified juvenile rheumatoid arthritis, left elbow
M08.029Unspecified juvenile rheumatoid arthritis, unspecified elbow

Includes

Official

ICD-10-CM does not list Includes notes for M08.021 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M08.021 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M08.021 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M08.021 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M08.021 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Age at onset documented as under 16 years
Evidence of inflammatory arthritis specifically in right elbow
Documentation that specific juvenile arthritis type cannot be determined
Physical examination findings of joint inflammation

MEAT Support

HCC Buddy guidance
Age at onset documented as under 16 years
Evidence of inflammatory arthritis specifically in right elbow
Documentation that specific juvenile arthritis type cannot be determined
Physical examination findings of joint inflammation

Audit Caution

HCC Buddy guidance
Incorrect laterality assignment when documentation is clear
Using when patient has adult-onset disease
Failing to use more specific juvenile arthritis codes when subtype is known
Coding joint symptoms rather than confirmed inflammatory disease

Common Mistakes

HCC Buddy guidance
M08.022 — Left elbow involvement versus right elbow
M08.029 — Unspecified elbow laterality when right side is documented
M25.521 — Elbow pain versus documented inflammatory arthritis
M08.3 — Juvenile chronic arthritis (polyarticular) when multiple joints involved

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 M08.021 an HCC code?

Yes. M08.021 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

V28HCC 93, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
0.175
V24HCC 40, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
0.307
ESRDHCC 40, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
0.000
RxHCCHCC 83, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
0.000

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 M08.021

For M08.021to 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 M08.021 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

M08.021 is the ICD-10-CM diagnosis code for unspecified juvenile rheumatoid arthritis, right elbow. Juvenile rheumatoid arthritis affecting the right elbow in a child, where the specific type of juvenile arthritis has not been determined. M08.021 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, M08.021 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, M08.021 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.

The '1' in the sixth position specifically indicates the right elbow; do not use this code for left elbow or bilateral involvement. Because M08.021 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 M08.021 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •The '1' in the sixth position specifically indicates the right elbow; do not use this code for left elbow or bilateral involvement.
  • •Verify documentation confirms right-sided involvement; if the side is not specified, use M08.029 instead.

Clinical Significance

Juvenile rheumatoid arthritis affecting the right elbow represents a chronic inflammatory condition with potential for growth disturbances and functional impairment. This diagnosis indicates need for specialized rheumatologic care and immunosuppressive therapy management in pediatric populations.

Documentation Requirements

  • ✓Age at onset documented as under 16 years
  • ✓Evidence of inflammatory arthritis specifically in right elbow
  • ✓Documentation that specific juvenile arthritis type cannot be determined
  • ✓Physical examination findings of joint inflammation
  • ✓Imaging studies showing joint changes if available
  • ✓Laboratory markers of inflammation
  • ✓Treatment history or current management plan
  • ✓Assessment of growth and development impact

Commonly Confused Codes

  • •M08.022: Left elbow involvement versus right elbow
  • •M08.029: Unspecified elbow laterality when right side is documented
  • •M25.521: Elbow pain versus documented inflammatory arthritis
  • •M08.3: Juvenile chronic arthritis (polyarticular) when multiple joints involved
  • •M06.052: Adult rheumatoid arthritis of right elbow

Child Codes

M08.021Unspecified juvenile rheumatoid arthritis, right elbow
HCC 93
M08.022Unspecified juvenile rheumatoid arthritis, left elbow
HCC 93
M08.029Unspecified juvenile rheumatoid arthritis, unspecified elbow
HCC 93

Code Hierarchy

└M08Juvenile arthritis└M08.0Unspecified juvenile rheumatoid arthritis└M08.02Unspecified juvenile rheumatoid arthritis of elbow└M08.021Unspecified juvenile rheumatoid arthritis, right elbow
└M08.021Unspecified juvenile rheumatoid arthritis, right elbow

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