M00.271
BillableOther streptococcal arthritis, right ankle and foot
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M00.271 an HCC code?
Yes. M00.271 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 M00.271
For M00.271to 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 M00.271 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M00.271 is the ICD-10-CM diagnosis code for other streptococcal arthritis, right ankle and foot. A bacterial infection of the right ankle and foot joints caused by streptococcus bacteria, causing inflammation and pain in that area. M00.271 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, M00.271 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, M00.271 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.
This code encompasses both ankle and foot joints; document which specific joints are affected for clinical clarity. Because M00.271 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 M00.271 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code encompasses both ankle and foot joints; document which specific joints are affected for clinical clarity
- •Confirm right-sided involvement is clearly stated in the clinical documentation
Clinical Significance
Septic arthritis of the right ankle and foot caused by non-pneumococcal streptococcal organisms is a serious infectious condition requiring emergent treatment with intravenous antibiotics and often surgical intervention. Involvement of the right ankle and foot can lead to significant functional disability and may require surgical drainage or arthrotomy. This condition reflects high healthcare complexity and resource needs, making it significant for risk adjustment.
Documentation Requirements
- ✓Provider documentation explicitly stating streptococcal septic arthritis or pyogenic arthritis with identified causative organism
- ✓Synovial fluid analysis results (cell count, Gram stain, crystal analysis to rule out gout/pseudogout)
- ✓Culture and sensitivity results identifying the specific streptococcal organism, or clinical rationale if culture-negative
- ✓Clinical signs and symptoms of joint infection (acute onset joint pain, swelling, warmth, erythema, fever, limited range of motion)
- ✓Documentation confirming right-sided involvement with imaging or examination findings specific to that side
- ✓Treatment plan including antibiotic regimen, duration, and any surgical intervention (arthrocentesis, irrigation and debridement, arthroscopy)
Commonly Confused Codes
- •M00.1x (Pneumococcal arthritis) — Use M00.1x when the causative organism is specifically Streptococcus pneumoniae; M00.2x covers Group A, Group B, and other non-pneumococcal streptococcal species
- •M00.8x (Arthritis due to other bacteria) — Use M00.8x for septic arthritis caused by non-streptococcal organisms such as Staphylococcus, Escherichia coli, or Pseudomonas
- •M00.0x (Staphylococcal arthritis) — Staphylococcal joint infections use M00.0x; do not confuse with streptococcal infections which use M00.2x