M86.529
BillableOther chronic hematogenous osteomyelitis, unspecified humerus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.529 an HCC code?
Yes. M86.529 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 M86.529
For M86.529 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 M86.529 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.529 is the ICD-10-CM diagnosis code for other chronic hematogenous osteomyelitis, unspecified humerus. A chronic bone infection of the upper arm bone (humerus) from a bloodstream source when the specific side is not documented. M86.529 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, M86.529 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, M86.529 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 unspecified laterality code should be used only when the medical record does not indicate left or right. Because M86.529 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 M86.529 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This unspecified laterality code should be used only when the medical record does not indicate left or right
- •Request clarification from the provider to determine laterality for more precise coding when possible
Clinical Significance
Other chronic hematogenous osteomyelitis of unspecified humerus represents a blood-borne bone infection affecting the upper arm bone with chronic progression but without laterality specification. This condition indicates systemic infection with targeted skeletal involvement requiring intensive treatment, though the unspecified nature may complicate precise clinical management and functional rehabilitation planning.
Documentation Requirements
- ✓Documentation of chronic osteomyelitis diagnosis
- ✓Evidence of hematogenous (blood-borne) etiology
- ✓Humerus involvement specified without laterality designation
- ✓Laboratory studies demonstrating systemic infection
- ✓Blood cultures or evidence of bacteremia when available
- ✓Treatment protocols including antibiotic therapy history
- ✓Imaging studies confirming humerus bone infection
- ✓Assessment of upper extremity function and treatment response
Commonly Confused Codes
- •M86.521 — Other chronic hematogenous osteomyelitis, right humerus (has laterality)
- •M86.522 — Other chronic hematogenous osteomyelitis, left humerus (has laterality)
- •M86.629 — Other chronic osteomyelitis, unspecified humerus (not specifically hematogenous)
- •M86.329 — Chronic multifocal osteomyelitis, unspecified humerus (multifocal pattern)