Z89.442
BillableAcquired absence of left ankle
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is Z89.442 an HCC code?
Yes. Z89.442 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 Z89.442
For Z89.442 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 Z89.442 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
Z89.442 is the ICD-10-CM diagnosis code for acquired absence of left ankle. A person is missing their left ankle due to amputation, injury, or surgical removal that occurred after birth. Z89.442 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, Z89.442 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 Z89.442 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.
Verify that the amputation level is at the ankle joint; amputations above the ankle are coded to the leg section (Z89.5x). Because Z89.442 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 Z89.442 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify that the amputation level is at the ankle joint; amputations above the ankle are coded to the leg section (Z89.5x).
- •Include documentation of the etiology and any complications or functional limitations related to the ankle absence.
Clinical Significance
Acquired absence of left ankle represents major lower extremity amputation at the ankle level with severe impact on mobility and functional independence. This condition reflects advanced underlying pathology and necessitates comprehensive amputation care including prosthetics and ongoing rehabilitation services.
Documentation Requirements
- ✓Complete absence of left ankle joint documented
- ✓Acquired nature and timing of amputation
- ✓Specific anatomical level at ankle specified
- ✓Medical indication or underlying cause
- ✓Current prosthetic device and functionality
- ✓Mobility assessment and ambulatory status
- ✓Rehabilitation progress and ongoing needs
- ✓Pain management and phantom limb treatment