M86.49
BillableChronic osteomyelitis with draining sinus, multiple sites
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.49 an HCC code?
Yes. M86.49 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 M86.49
For M86.49 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 M86.49 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.49 is the ICD-10-CM diagnosis code for chronic osteomyelitis with draining sinus, multiple sites. A chronic bone infection affecting multiple sites in the body that has created persistent drainage channels through the skin. M86.49 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, M86.49 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, M86.49 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 requires documentation of multiple affected sites; if only one site is involved, use site-specific codes instead. Because M86.49 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 M86.49 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code requires documentation of multiple affected sites; if only one site is involved, use site-specific codes instead
- •The presence of a draining sinus is a key clinical indicator that distinguishes this from other chronic osteomyelitis presentations
Clinical Significance
Chronic osteomyelitis with draining sinus affecting multiple sites represents the most complex form of chronic bone infection with widespread skeletal involvement and persistent drainage pathways. This condition indicates severe systemic infection requiring aggressive multi-modal treatment approaches, prolonged hospitalization, and intensive monitoring, substantially impacting all aspects of patient health and functionality.
Documentation Requirements
- ✓Documentation of chronic osteomyelitis diagnosis
- ✓Clear evidence of draining sinus tracts at multiple locations
- ✓Specification of multiple anatomic sites involved
- ✓Detailed description of each affected site and drainage pattern
- ✓Comprehensive microbiological studies from multiple sites
- ✓Extensive imaging studies showing multifocal infection
- ✓Complex treatment regimens including multiple antibiotics
- ✓Assessment of overall functional status and prognosis
Commonly Confused Codes
- •M86.48 — Chronic osteomyelitis with draining sinus, other site (single site, not multiple)
- •M86.49 — Chronic multifocal osteomyelitis, multiple sites (multifocal but no draining sinus)
- •M86.69 — Other chronic osteomyelitis, multiple sites (no draining sinus component)
- •M86.59 — Other chronic hematogenous osteomyelitis, multiple sites (different etiology)