M86.60
BillableOther chronic osteomyelitis, unspecified site
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.60 an HCC code?
Yes. M86.60 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 M86.60
For M86.60 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 M86.60 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.60 is the ICD-10-CM diagnosis code for other chronic osteomyelitis, unspecified site. A long-term bone infection of unknown or unspecified location in the body. M86.60 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, M86.60 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, M86.60 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.
Avoid using this code if the infection site can be identified; be specific about location. Because M86.60 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 M86.60 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Avoid using this code if the infection site can be identified; be specific about location
- •Query provider for clarification on infection site when possible
Clinical Significance
This code represents chronic osteomyelitis of unspecified etiology and location, indicating incomplete documentation that limits optimal patient care planning. While still capturing the chronic nature of bone infection requiring ongoing treatment, more specific coding would better reflect disease severity and treatment needs.
Documentation Requirements
- ✓Documentation of chronic nature (>6 weeks duration or recurrent)
- ✓Evidence of bone infection without specified etiology
- ✓Unspecified anatomical location of infection
- ✓Imaging studies confirming presence of osteomyelitis
- ✓Laboratory markers supporting infection or inflammation
- ✓Assessment of functional impact and disability
- ✓Treatment plan for chronic bone infection
- ✓Attempts to identify specific site and etiology when possible
Commonly Confused Codes
- •M86.9 — Osteomyelitis, unspecified (lacks chronic specification)
- •M86.50 — Other chronic hematogenous osteomyelitis, unspecified site (hematogenous origin)
- •M86.40 — Chronic osteomyelitis with draining sinus, unspecified site (has sinus)
- •M86.10 — Other acute osteomyelitis, unspecified site (acute phase)
- •M89.9 — Disorder of bone, unspecified (non-infectious pathology)