M86.569
BillableOther chronic hematogenous osteomyelitis, unspecified tibia and fibula
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.569 an HCC code?
Yes. M86.569 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 M86.569
For M86.569 to 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 M86.569 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.569 is the ICD-10-CM diagnosis code for other chronic hematogenous osteomyelitis, unspecified tibia and fibula. A chronic bone infection of the shinbone and smaller leg bone (tibia and fibula) that developed from bacteria spreading through the bloodstream, with unspecified laterality. M86.569 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering other osteopathies (m86-m90).
Under the CMS-HCC V28 risk adjustment model, M86.569 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, M86.569 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 this code only when laterality cannot be determined from the medical record. Because M86.569 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 M86.569 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when laterality cannot be determined from the medical record
- •Review imaging reports and clinical documentation to determine if right or left leg is affected
Clinical Significance
This code captures chronic hematogenous osteomyelitis affecting the tibia and fibula when laterality is unspecified. While representing a serious bone infection requiring intensive treatment, the lack of laterality specification indicates potential documentation improvements needed for optimal care coordination and treatment planning.
Documentation Requirements
- ✓Documentation of chronic osteomyelitis (>6 weeks or recurrent)
- ✓Evidence of hematogenous origin (bloodstream seeding)
- ✓Involvement of tibia and/or fibula without laterality specification
- ✓Imaging confirmation of bone infection
- ✓Laboratory markers of infection or inflammation
- ✓Assessment of lower extremity function
- ✓Treatment history and current management approach
- ✓Justification for unspecified laterality (bilateral or unclear documentation)
Commonly Confused Codes
- •M86.561 — Other chronic hematogenous osteomyelitis, right tibia and fibula (specific side)
- •M86.562 — Other chronic hematogenous osteomyelitis, left tibia and fibula (specific side)
- •M86.669 — Other chronic osteomyelitis, unspecified tibia and fibula (non-hematogenous)
- •M86.469 — Chronic osteomyelitis with draining sinus, unspecified tibia and fibula (has sinus)
- •M86.169 — Other acute osteomyelitis, unspecified tibia and fibula (acute phase)