M89.642
BillableOsteopathy after poliomyelitis, left hand
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M89.642 an HCC code?
Yes. M89.642 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 M89.642
For M89.642 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 M89.642 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M89.642 is the ICD-10-CM diagnosis code for osteopathy after poliomyelitis, left hand. Bone disease that develops as a long-term consequence of polio infection, affecting the left hand. M89.642 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, M89.642 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, M89.642 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 is used for post-polio sequelae affecting bone structure; ensure polio history is documented. Because M89.642 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 M89.642 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code is used for post-polio sequelae affecting bone structure; ensure polio history is documented
- •Verify laterality is clearly documented as left before assigning this code
Clinical Significance
Left hand post-polio osteopathy involves chronic bone deterioration in the left hand as a late consequence of poliomyelitis infection, potentially severely compromising hand function and independence in daily activities. This represents a functionally significant long-term sequela.
Documentation Requirements
- ✓Clear history of previous poliomyelitis infection
- ✓Specific documentation of left hand bone involvement
- ✓Current imaging showing post-polio changes in hand bones
- ✓Left hand functional capacity evaluation
- ✓Grip and pinch strength testing
- ✓Fine motor coordination assessment
- ✓Impact on activities of daily living and independence
- ✓Hand therapy and adaptive equipment recommendations
Commonly Confused Codes
- •G14 — Post-polio syndrome primarily neurological, not bone-related
- •M25.542 — Left hand pain is symptomatic presentation only
- •S62.602A — Hand fracture represents acute trauma
- •M19.042 — Primary hand osteoarthritis lacks post-infectious etiology
- •M87.842 — Other osteonecrosis has different underlying mechanism