M86.8X8
BillableOther osteomyelitis, other site
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.8X8 an HCC code?
Yes. M86.8X8 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 M86.8X8
For M86.8X8 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 M86.8X8 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.8X8 is the ICD-10-CM diagnosis code for other osteomyelitis, other site. A bone infection (osteomyelitis) affecting an anatomical site other than the standard limb locations that doesn't fit into other specific osteomyelitis categories. M86.8X8 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, M86.8X8 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, M86.8X8 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 for osteomyelitis of unusual sites such as the pelvis, ribs, or vertebrae when not otherwise specified. Because M86.8X8 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 M86.8X8 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code for osteomyelitis of unusual sites such as the pelvis, ribs, or vertebrae when not otherwise specified
- •Document the specific anatomical site clearly in the medical record for clinical reference
Clinical Significance
Other osteomyelitis at other anatomical sites represents bone infection in unusual locations that doesn't conform to standard acute or chronic patterns and doesn't fit typical extremity classifications. This indicates complex clinical scenarios requiring specialized evaluation and treatment approaches based on unique anatomical considerations and infection characteristics.
Documentation Requirements
- ✓Clear documentation of osteomyelitis at specified unusual site
- ✓Rationale for 'other' classification versus acute or chronic
- ✓Specific identification of affected bone(s) not in standard categories
- ✓Supporting diagnostic imaging confirming bone involvement
- ✓Laboratory or microbiological studies when available
- ✓Specialized treatment approach based on anatomical location
- ✓Assessment of functional impact specific to affected site
- ✓Documentation justifying both 'other osteomyelitis' and 'other site' designations