Z89.422
BillableAcquired absence of other left toe(s)
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is Z89.422 an HCC code?
Yes. Z89.422 maps to Amputation Status, Lower Limb/Amputation Complications under the V24 model but is not retained in V28.
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 Z89.422
For Z89.422 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 Z89.422 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
Z89.422 is the ICD-10-CM diagnosis code for acquired absence of other left toe(s). A person who has lost one or more of the smaller toes (not the big toe) on their left foot due to amputation or other acquired cause. Z89.422 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 older CMS-HCC V24 model, Z89.422 maps to Amputation Status, Lower Limb/Amputation Complications (HCC 189) with a community, non-dual, aged base RAF weight of 0.350. 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.
Distinguish between great toe loss and loss of other toes; this code is for non-great toes on the left. Because Z89.422 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 Z89.422 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Distinguish between great toe loss and loss of other toes; this code is for non-great toes on the left
- •Multiple toe loss may be coded with additional codes if different toes on different feet are affected
Clinical Significance
Acquired absence of other left toes (excluding great toe) represents functional impairment affecting balance and ambulation. This condition typically results from progressive vascular compromise or diabetic complications, indicating need for ongoing surveillance and preventive care management.
Documentation Requirements
- ✓Acquired absence clearly stated
- ✓Left laterality specifically documented
- ✓Exclusion of great toe from amputation
- ✓Specific toes affected when determinable
- ✓Underlying pathology or cause documented
- ✓Current functional capacity assessment
- ✓Prosthetic fitting or orthotic needs
- ✓Preventive care measures implemented