M02.9 ICD-10-CM Code: Reactive arthropathy, unspecified
M02.9 maps to CMS-HCC V28 92. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools
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FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Infectious arthropathies (M00-M02)
M02.9
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceReactive arthropathy, unspecified
Joint inflammation that develops as a reaction to an infection or other trigger, but the specific affected joint location is not documented.
Buddy Insight
This represents reactive arthropathy when the specific joint location is not documented or specified.
CMS-HCC V28
MappedHCC 92
Coefficient HCC 92: 0.479 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 055
Code-level coefficient reference
ESRD/PACE
MappedHCC 39
Code-level coefficient reference
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for M02.9. Check the code and parent instructions in the Code Book.
Excludes 2
Official- arthropathic psoriasis (L40.5-)Inherited from M00-M99
- certain conditions originating in the perinatal period (P04-P96)Inherited from M00-M99
- certain infectious and parasitic diseases (A00-B99)Inherited from M00-M99
- compartment syndrome (traumatic) (T79.A-)Inherited from M00-M99
- complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from M00-M99
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Inherited from M00-M99
- endocrine, nutritional and metabolic diseases (E00-E88)Inherited from M00-M99
- injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from M00-M99
- neoplasms (C00-D49)Inherited from M00-M99
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from M00-M99
Related Codes
Includes
OfficialNo Includes notes are included in this display for M02.9. Check the code and parent instructions in the Code Book.
Excludes 1
Official- Behçet's disease (M35.2)Inherited from M02
- direct infections of joint in infectious and parasitic diseases classified elsewhere (M01.-)Inherited from M02
- postmeningococcal arthritis (A39.84)Inherited from M02
- mumps arthritis (B26.85)Inherited from M02
- rubella arthritis (B06.82)Inherited from M02
- syphilis arthritis (late) (A52.77)Inherited from M02
- rheumatic fever (I00)Inherited from M02
- tabetic arthropathy [Charcôt's] (A52.16)Inherited from M02
Code First
Official- underlying disease, such as:Inherited from M02
- congenital syphilis [Clutton's joints] (A50.5)Inherited from M02
- enteritis due to Yersinia enterocolitica (A04.6)Inherited from M02
- infective endocarditis (I33.0)Inherited from M02
- viral hepatitis (B15-B19)Inherited from M02
Use Additional
OfficialNo Use Additional Code instructions are included in this display for M02.9. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for M02.9. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 M02.9 an HCC code?
Yes. M02.9 (Reactive arthropathy, unspecified) maps to HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.479. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: M02.9 is billable and maps to V28 HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- M02.9
- Description
- Reactive arthropathy, unspecified
- HCC (V28)
- HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
- RAF reference coefficient
- 0.479
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work M02.9 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for M02.9
For M02.9, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- 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
Coder workflow notes
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What This Code Means
M02.9 is the ICD-10-CM diagnosis code for reactive arthropathy, unspecified. Joint inflammation that develops as a reaction to an infection or other trigger, but the specific affected joint location is not documented. M02.9 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering infectious arthropathies (m00-m02).
Under the CMS-HCC V28 risk adjustment model, M02.9 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis (HCC 92) with a source-labeled community, non-dual, aged reference coefficient of 0.479. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
This is the least specific code in the reactive arthropathy category; use only when site information is completely unavailable. For M02.9, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for M02.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is the least specific code in the reactive arthropathy category; use only when site information is completely unavailable
- •Query the provider for site-specific information to allow assignment of a more detailed code (M02.8x series)
Clinical Significance
This represents reactive arthropathy when the specific joint location is not documented or specified. This unspecified code indicates incomplete clinical documentation and may suggest need for further evaluation to identify the affected joints for proper treatment planning and monitoring.
Documentation Requirements
- ✓Clinical evidence of joint inflammation consistent with reactive arthropathy
- ✓Documentation of reactive nature - inflammation secondary to remote infection
- ✓Confirmation that specific joint location is truly unspecified
- ✓Evidence ruling out direct septic arthritis
- ✓Documentation of triggering infection or infectious process (if identified)
- ✓Physical examination findings consistent with arthritis
- ✓Exclusion of other arthropathy types when possible
- ✓Justification for why joint location cannot be specified
Commonly Confused Codes
- •Specific site reactive arthropathy codes (M02.8XX) when location is documented
- •M06.9: Rheumatoid arthritis, unspecified (autoimmune vs reactive)
- •M13.9: Arthritis, unspecified (nonspecific vs reactive arthritis)
- •M25.9: Joint disorder, unspecified (general joint problem vs specific arthropathy)
- •M79.3: Panniculitis, unspecified (soft tissue vs joint inflammation)