M86.542
BillableOther chronic hematogenous osteomyelitis, left hand
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.542 an HCC code?
Yes. M86.542 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 M86.542
For M86.542 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 M86.542 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.542 is the ICD-10-CM diagnosis code for other chronic hematogenous osteomyelitis, left hand. A chronic bone infection of the left hand bones that developed from bacteria spreading through the bloodstream. M86.542 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, M86.542 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, M86.542 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.
Ensure laterality is clearly documented as left before assigning this code. Because M86.542 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 M86.542 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Ensure laterality is clearly documented as left before assigning this code
- •This encompasses all carpal, metacarpal, and phalangeal bones of the left hand
Clinical Significance
Chronic hematogenous osteomyelitis affecting the left hand bones represents a severe infection requiring intensive treatment due to the hand's functional complexity. This condition often results in prolonged disability and may require surgical intervention, significantly impacting the patient's ability to perform activities of daily living.
Documentation Requirements
- ✓Documentation of chronic duration (minimum 6 weeks or recurrent episodes)
- ✓Clear evidence of hematogenous spread (bloodstream origin)
- ✓Specific identification of left hand bone involvement
- ✓Radiographic confirmation of bone infection or osteolytic changes
- ✓Laboratory studies supporting active infection (ESR, CRP, cultures)
- ✓Assessment of functional impairment and disability
- ✓Documentation of antibiotic therapy and surgical interventions
- ✓Differentiation from acute osteomyelitis or post-traumatic infection