M02.121
BillablePostdysenteric arthropathy, right elbow
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M02.121 an HCC code?
Yes. M02.121 maps to Bone/Joint/Muscle Infections/Necrosis under the CMS-HCC V28 risk adjustment model (and Bone/Joint/Muscle Infections/Necrosis 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 M02.121
For M02.121to 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 M02.121 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M02.121 is the ICD-10-CM diagnosis code for postdysenteric arthropathy, right elbow. Joint inflammation and pain in the right elbow that develops as a complication following a dysentery infection. M02.121 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, M02.121 maps to Bone/Joint/Muscle Infections/Necrosis (HCC 92) with a community, non-dual, aged base RAF weight of 0.209. Under the older V24 model, M02.121 mapped to the same category but with a base RAF weight of 0.482 — 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.
Verify right elbow is documented; left elbow requires code M02.122. Because M02.121 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 M02.121 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify right elbow is documented; left elbow requires code M02.122
- •Confirm the arthropathy is reactive to dysentery, not primary elbow pathology
Clinical Significance
This code identifies postdysenteric arthropathy specifically affecting the right elbow, representing a reactive inflammatory joint condition following dysentery infection. The specificity of laterality is important for accurate treatment planning and demonstrates precise clinical documentation of this chronic infectious arthropathy.
Documentation Requirements
- ✓History of dysentery or severe infectious diarrheal illness
- ✓Documentation of right elbow joint involvement specifically
- ✓Evidence of arthritis symptoms (pain, swelling, stiffness, limited motion)
- ✓Temporal relationship between infection and joint symptoms
- ✓Chronic or ongoing nature of joint inflammation
- ✓Physical examination findings consistent with arthropathy
- ✓Exclusion of other arthritis types (septic, rheumatoid, osteoarthritis)
Commonly Confused Codes
- •M02.122 — Postdysenteric arthropathy, left elbow (opposite laterality)
- •M02.129 — Postdysenteric arthropathy, unspecified elbow (use when laterality unknown)
- •M00.021 — Staphylococcal arthritis, right elbow (septic arthritis, not reactive)
- •M06.821 — Other specified rheumatoid arthritis, right elbow (different etiology)
- •M25.521 — Pain in right elbow (symptom code, not diagnostic)