M86.312
BillableChronic multifocal osteomyelitis, left shoulder
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.312 an HCC code?
Yes. M86.312 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 M86.312
For M86.312 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 M86.312 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.312 is the ICD-10-CM diagnosis code for chronic multifocal osteomyelitis, left shoulder. A long-standing bone infection affecting multiple bones, specifically involving the left shoulder. M86.312 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, M86.312 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, M86.312 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 indicates the left shoulder is one of multiple affected sites; document all other involved locations separately. Because M86.312 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 M86.312 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code indicates the left shoulder is one of multiple affected sites; document all other involved locations separately.
- •Confirm laterality is documented as 'left' in the medical record.
Clinical Significance
Chronic multifocal osteomyelitis of the left shoulder represents a complex, persistent bone infection requiring intensive medical management and significantly impacting patient functionality. The multifocal nature indicates widespread bone involvement, necessitating comprehensive treatment approaches and long-term monitoring for systemic complications.
Documentation Requirements
- ✓Explicit documentation of chronic osteomyelitis diagnosis
- ✓Clear specification of multifocal involvement pattern
- ✓Precise anatomic identification of left shoulder
- ✓Clinical evidence of persistent infection (cultures, inflammatory markers)
- ✓Imaging studies confirming multifocal bone involvement
- ✓Treatment regimen documentation including antibiotic duration
- ✓Surgical history and planned interventions
- ✓Assessment of functional limitations and disability