M86.522
BillableOther chronic hematogenous osteomyelitis, left humerus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.522 an HCC code?
Yes. M86.522 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 M86.522
For M86.522 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 M86.522 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.522 is the ICD-10-CM diagnosis code for other chronic hematogenous osteomyelitis, left humerus. A chronic bone infection of the left upper arm bone (humerus) that originated from a bloodstream infection. M86.522 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, M86.522 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, M86.522 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.
Verify documentation specifies the left humerus to justify this code selection. Because M86.522 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 M86.522 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify documentation specifies the left humerus to justify this code selection
- •Distinguish between humerus infections and shoulder joint infections, which use different code ranges
Clinical Significance
Other chronic hematogenous osteomyelitis of the left humerus indicates a blood-borne bone infection that has progressed to chronic status, specifically involving the left upper arm bone. This condition represents systemic infection with localized skeletal manifestation requiring intensive antibiotic therapy and ongoing monitoring, substantially affecting upper extremity mobility and functional independence.
Documentation Requirements
- ✓Clear documentation of chronic osteomyelitis diagnosis
- ✓Evidence of hematogenous origin through bloodstream spread
- ✓Anatomic specification of left humerus involvement
- ✓Laboratory evidence of systemic infection or bacteremia
- ✓Blood cultures or other markers of hematogenous spread
- ✓Comprehensive treatment history including IV antibiotics
- ✓Imaging studies confirming left humerus bone infection
- ✓Functional assessment including range of motion and strength
Commonly Confused Codes
- •M86.521 — Other chronic hematogenous osteomyelitis, right humerus (incorrect laterality)
- •M86.622 — Other chronic osteomyelitis, left humerus (not specifically hematogenous)
- •M86.322 — Chronic multifocal osteomyelitis, left humerus (multifocal pattern)
- •M86.422 — Chronic osteomyelitis with draining sinus, left humerus (has draining sinus)