M86.469
BillableChronic osteomyelitis with draining sinus, unspecified tibia and fibula
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.469 an HCC code?
Yes. M86.469 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 M86.469
For M86.469 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 M86.469 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.469 is the ICD-10-CM diagnosis code for chronic osteomyelitis with draining sinus, unspecified tibia and fibula. A chronic bone infection of the shin bones (tibia and fibula) with an unspecified side that has created an open drainage channel through the skin, allowing infected material to drain continuously. M86.469 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, M86.469 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, M86.469 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 the medical record does not specify right or left lower leg. Because M86.469 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 M86.469 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 the medical record does not specify right or left lower leg
- •Query the provider if laterality can be determined from imaging or clinical documentation to assign a more specific code
Clinical Significance
Chronic osteomyelitis with draining sinus affecting unspecified tibia and fibula represents a serious bone infection with persistent external drainage requiring comprehensive medical management. Despite the unspecified laterality, this condition indicates significant morbidity with ongoing infection requiring prolonged treatment and monitoring for complications.
Documentation Requirements
- ✓Clear documentation of chronic osteomyelitis diagnosis
- ✓Evidence of active draining sinus tract
- ✓Tibia and fibula involvement specified without laterality
- ✓Description of drainage patterns and characteristics
- ✓Laboratory studies including cultures and inflammatory markers
- ✓Radiographic evidence of osteomyelitis and sinus formation
- ✓Treatment history and current management protocols
- ✓Documentation of complications or treatment responses
Commonly Confused Codes
- •M86.461 — Chronic osteomyelitis with draining sinus, right tibia and fibula (has laterality)
- •M86.462 — Chronic osteomyelitis with draining sinus, left tibia and fibula (has laterality)
- •M86.669 — Other chronic osteomyelitis, unspecified tibia and fibula (no draining sinus)
- •M86.479 — Chronic osteomyelitis with draining sinus, unspecified ankle and foot (different anatomy)