M00.871
BillableArthritis due to other bacteria, right ankle and foot
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M00.871 an HCC code?
Yes. M00.871 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 M00.871
For M00.871to 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 M00.871 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M00.871 is the ICD-10-CM diagnosis code for arthritis due to other bacteria, right ankle and foot. Bacterial infection causing inflammation and swelling in the right ankle and foot joints, caused by bacteria other than the most common types. M00.871 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, M00.871 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, M00.871 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 the bacterial organism is documented; if not specified, use M00.879. Because M00.871 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 M00.871 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify the bacterial organism is documented; if not specified, use M00.879
- •Confirm right ankle and foot laterality is clearly documented in the medical record
Clinical Significance
Bacterial arthritis of the right ankle and foot involves multiple complex joints essential for ambulation and balance. This condition can severely impact mobility and requires aggressive treatment to prevent permanent disability and chronic pain syndromes.
Documentation Requirements
- ✓Confirmation of 'other bacteria' as causative organism
- ✓Specific documentation of right ankle and foot involvement
- ✓Microbiological evidence of bacterial infection
- ✓Clinical presentation of infectious arthritis
- ✓Documentation of antibiotic treatment regimen
- ✓Assessment of weight-bearing capacity and gait
- ✓Laboratory markers of infection
- ✓Exclusion of cellulitis versus true joint infection
Commonly Confused Codes
- •M00071 — Streptococcal arthritis of right ankle/foot (different organism)
- •M00017 — Staphylococcal arthritis of right ankle/foot (specific bacteria)
- •M06.871 — Other rheumatoid arthritis of right ankle/foot (autoimmune)
- •L03.116 — Cellulitis of right foot (soft tissue infection)
- •M19.071 — Primary osteoarthritis of right ankle/foot (degenerative)