M00.842
BillableArthritis due to other bacteria, left hand
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M00.842 an HCC code?
Yes. M00.842 maps to Bone/Joint/Muscle/Severe Soft Tissue 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 M00.842
For M00.842to 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 M00.842 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M00.842 is the ICD-10-CM diagnosis code for arthritis due to other bacteria, left hand. Infection and inflammation of the left hand joints caused by bacteria other than the common ones typically associated with arthritis. M00.842 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, M00.842 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis (HCC 92) with a community, non-dual, aged base RAF weight of 0.479. Under the older CMS-HCC V24 model, M00.842 maps to Bone/Joint/Muscle Infections/Necrosis (HCC 39) with a community, non-dual, aged base RAF weight of 0.401. 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 the left hand is documented as the affected site. Because M00.842 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 M00.842 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify the left hand is documented as the affected site
- •Note whether the infection involves single or multiple hand joints
Clinical Significance
Bacterial arthritis of the left hand represents a serious threat to fine motor function and hand dexterity. The multiple small joints involved make this condition complex to treat and may result in significant functional disability if not managed aggressively.
Documentation Requirements
- ✓Documentation of 'other bacteria' as infectious organism
- ✓Clear identification of left hand joint involvement
- ✓Laboratory evidence of bacterial infection
- ✓Clinical findings consistent with infectious arthritis
- ✓Evidence of appropriate antibiotic treatment
- ✓Functional assessment of left hand capabilities
- ✓Inflammatory markers and culture results
- ✓Differentiation from soft tissue infection versus joint infection
Commonly Confused Codes
- •M00042 — Streptococcal arthritis of left hand (different bacterial type)
- •M00014 — Staphylococcal arthritis of left hand (specific organism)
- •M06.842 — Other rheumatoid arthritis of left hand (autoimmune)
- •L03.112 — Cellulitis of left hand (soft tissue infection)
- •M19.042 — Primary osteoarthritis of left hand (degenerative)