M01.X31
BillableDirect infection of right wrist in infectious and parasitic diseases classified elsewhere
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M01.X31 an HCC code?
Yes. M01.X31 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 M01.X31
For M01.X31to 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 M01.X31 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M01.X31 is the ICD-10-CM diagnosis code for direct infection of right wrist in infectious and parasitic diseases classified elsewhere. Direct infection of the right wrist joint resulting from an infectious or parasitic disease classified elsewhere. M01.X31 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, M01.X31 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, M01.X31 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.
Requires a primary code from Chapter 1 (A00-B99) for the underlying infectious disease. Because M01.X31 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 M01.X31 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Direct infection of the right wrist joint secondary to classified infectious or parasitic diseases represents a complex condition affecting fine motor function and hand dexterity. This diagnosis requires comprehensive management addressing both the underlying systemic infection and preservation of wrist joint function.
Documentation Requirements
- ✓Clear documentation of right wrist joint infection
- ✓Primary diagnosis of underlying infectious or parasitic disease (A00-B99)
- ✓Evidence of direct causal relationship between systemic disease and joint infection
- ✓Physical examination documenting wrist joint inflammation and functional limitation
- ✓Laboratory evidence of infection (elevated white count, inflammatory markers)
- ✓Imaging studies confirming wrist joint involvement (X-ray, MRI, ultrasound)
- ✓Joint aspiration and synovial fluid analysis when performed
- ✓Treatment plan for both systemic infection and joint-specific interventions
Commonly Confused Codes
- •M00.931 — Pyogenic arthritis, right wrist (bacterial infection not from classified disease)
- •M25.531 — Pain in right wrist (joint pain without infectious etiology)
- •M01.X32 — Direct infection of left wrist in infectious diseases classified elsewhere
- •A18.02 — Tuberculous arthritis (when tuberculosis is the specific underlying cause)