Z89.439
BillableAcquired absence of unspecified foot
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is Z89.439 an HCC code?
Yes. Z89.439 maps to Amputation Status, Lower Limb/Amputation Complications under the CMS-HCC V28 risk adjustment model (and Amputation Status, Lower Limb/Amputation Complications 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 Z89.439
For Z89.439 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 Z89.439 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
Z89.439 is the ICD-10-CM diagnosis code for acquired absence of unspecified foot. A person is missing their entire foot, but the specific side (left or right) is not documented or is unspecified. Z89.439 sits in the ICD-10-CM chapter for factors influencing health status and contact with health services (z00-z99), within the section covering persons with potential health hazards related to family and personal history and certain conditions influencing health status (z77-z99).
Under the CMS-HCC V28 risk adjustment model, Z89.439 maps to Amputation Status, Lower Limb/Amputation Complications (HCC 409) with a community, non-dual, aged base RAF weight of 0.350. The V24 model used during the PY2024–PY2025 transition mapped Z89.439 the same way and at the same RAF weight. 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 is a less specific code; attempt to determine laterality from medical records or query the provider to assign Z89.431 or Z89.432. Because Z89.439 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 Z89.439 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Acquired absence of unspecified foot represents major lower extremity amputation with severe functional consequences when laterality cannot be determined. Despite incomplete specificity, this indicates substantial underlying pathology requiring comprehensive amputation care and rehabilitation services.
Documentation Requirements
- ✓Complete foot absence documented as acquired
- ✓Reason for unspecified laterality explained
- ✓Level of amputation at foot specified
- ✓Underlying medical condition or cause
- ✓Current prosthetic status and functionality
- ✓Ambulatory capacity and mobility aids
- ✓Rehabilitation services and progress notes
- ✓Complication prevention and monitoring