Z44.121
BillableEncounter for fitting and adjustment of partial artificial right leg
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is Z44.121 an HCC code?
Yes. Z44.121 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 Z44.121
For Z44.121to 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 Z44.121 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
Z44.121 is the ICD-10-CM diagnosis code for encounter for fitting and adjustment of partial artificial right leg. A patient visit to have a partial artificial leg (prosthetic) fitted or adjusted on the right side of the body. Z44.121 sits in the ICD-10-CM chapter for factors influencing health status and contact with health services (z00-z99), within the section covering encounters for other specific health care (z40-z53).
Under the CMS-HCC V28 risk adjustment model, Z44.121 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 Z44.121 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.
A partial prosthetic replaces only part of the leg; ensure documentation confirms this distinction from a complete prosthetic. Because Z44.121 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 Z44.121 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •A partial prosthetic replaces only part of the leg; ensure documentation confirms this distinction from a complete prosthetic
- •This code is more specific than Z44.101 and should be used when the partial nature is documented
Clinical Significance
This code indicates a patient has undergone partial lower limb amputation on the right side requiring prosthetic management, representing moderate functional impairment. Partial prosthetics typically involve below-knee or similar amputations with preserved joint function above the amputation site.
Documentation Requirements
- ✓Documentation specifying partial artificial leg prosthetic
- ✓Clear indication this is for right leg prosthesis
- ✓Type of encounter (fitting, adjustment, repair, replacement)
- ✓Patient's underlying partial amputation status
- ✓Level of amputation requiring partial prosthetic (e.g., below-knee)
- ✓Functional assessment and prosthetic goals
- ✓Provider specialty performing prosthetic services
- ✓Any complications with current partial prosthetic device
Commonly Confused Codes
- •Z44.101 — Use when prosthetic type is unspecified rather than partial
- •Z44.111 — Use when documentation specifies complete rather than partial prosthetic
- •Z44.122 — Use for left leg instead of right leg partial prosthetic
- •Z44.129 — Use when laterality is unspecified for partial prosthetic
- •Z89.411 — This is amputation status, not prosthetic encounter