M00.869
BillableArthritis due to other bacteria, unspecified knee
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M00.869 an HCC code?
Yes. M00.869 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 M00.869
For M00.869to 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 M00.869 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M00.869 is the ICD-10-CM diagnosis code for arthritis due to other bacteria, unspecified knee. Bacterial infection causing inflammation and swelling in the knee joint when the specific side (left or right) is not specified or documented. M00.869 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, M00.869 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, M00.869 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 only when laterality is truly unspecified or bilateral involvement is not separately coded. Because M00.869 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 M00.869 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use only when laterality is truly unspecified or bilateral involvement is not separately coded
- •Attempt to clarify laterality with the provider to assign a more specific code
Clinical Significance
Bacterial arthritis of unspecified knee indicates a serious infection of this critical weight-bearing joint, though documentation lacks laterality specification. This condition requires urgent treatment to prevent cartilage destruction and permanent mobility impairment.
Documentation Requirements
- ✓Evidence of 'other bacteria' causing knee infection
- ✓Documentation of knee joint involvement without laterality
- ✓Bacterial culture or microbiological confirmation
- ✓Signs and symptoms of infectious arthritis
- ✓Treatment with systemic antibiotics
- ✓Assessment of knee mobility and weight-bearing status
- ✓Laboratory evidence of infection and inflammation
- ✓Attempt to clarify laterality for complete documentation
Commonly Confused Codes
- •M00.861/M00.862 — Same condition with specific laterality
- •M00069 — Streptococcal arthritis of unspecified knee (different organism)
- •M00019 — Staphylococcal arthritis of unspecified knee (specific bacteria)
- •M06.869 — Other rheumatoid arthritis of unspecified knee (autoimmune)
- •M17.10 — Unilateral primary osteoarthritis of unspecified knee (degenerative)