M01.X49
BillableDirect infection of unspecified hand 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.X49 an HCC code?
Yes. M01.X49 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.X49
For M01.X49to 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.X49 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M01.X49 is the ICD-10-CM diagnosis code for direct infection of unspecified hand in infectious and parasitic diseases classified elsewhere. An infection in the hand joint (side not specified) caused by a disease classified elsewhere, such as tuberculosis or a parasitic infection. M01.X49 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.X49 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.X49 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.
Use when the laterality of hand involvement is not documented or when both hands are affected. Because M01.X49 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.X49 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use when the laterality of hand involvement is not documented or when both hands are affected
- •Must be accompanied by a secondary code identifying the underlying infectious or parasitic disease
Clinical Significance
This code represents direct hand joint infection secondary to classified infectious or parasitic diseases when laterality is not specified, indicating incomplete documentation. The condition poses significant risk for loss of essential hand function and requires comprehensive treatment to preserve manual dexterity and grip strength.
Documentation Requirements
- ✓Documentation of hand joint infection without laterality specification
- ✓Required primary code for underlying infectious or parasitic disease
- ✓Evidence that hand infection results from direct extension of classified disease
- ✓Physical examination findings consistent with infectious hand arthropathy
- ✓Laboratory studies indicating systemic infection and inflammation
- ✓Imaging confirmation of hand joint involvement
- ✓Microbiological data from joint samples when available
- ✓Treatment protocol addressing both underlying condition and hand infection
Commonly Confused Codes
- •M00.949 — Pyogenic arthritis, unspecified hand (bacterial infection not from classified disease)
- •M25.549 — Pain in unspecified hand (joint symptoms without infectious cause)
- •M01.X41 — Direct infection of right hand (when laterality is actually documented)
- •M01.X42 — Direct infection of left hand (when laterality is actually documented)