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Z89.449 ICD-10-CM Code: Acquired absence of unspecified ankle

Z89.449 maps to CMS-HCC V28 409. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools

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Code lookupZ89.449

FY 2026 Apr update / Factors influencing health status and contact with health services (Z00-Z99) / Persons with potential health hazards related to family and personal history and certain conditions influencing health status (Z77-Z99)

Z89.449

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Acquired absence of unspecified ankle

A person is missing an ankle, but the specific side (left or right) is not documented or is unspecified.

Buddy the Bee presenting code insight

Buddy Insight

Acquired absence of unspecified ankle represents major lower extremity amputation at ankle level when laterality cannot be determined from documentation.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 409

Coefficient HCC 409: 0.598 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 254

Code-level coefficient reference

ESRD/PACE

HCC 189

Code-level coefficient reference

RXHCC

N/A

—

Not mapped

Code Book Path

Official
Z89.4Acquired absence of toe(s), foot, and ankleZ89.44Acquired absence of ankleZ89.449Acquired absence of unspecified ankle

Inclusion Terms

Official
  • Disarticulation of ankleInherited from Z89.44

Excludes 2

Official

No Excludes 2 notes are included in this display for Z89.449. Check the code and parent instructions in the Code Book.

Related Codes

Official
Z89.441Acquired absence of right ankleZ89.442Acquired absence of left ankle

Includes

Official
  • amputation statusInherited from Z89
  • postprocedural loss of limbInherited from Z89
  • post-traumatic loss of limbInherited from Z89

Excludes 1

Official
  • acquired deformities of limbs (M20-M21)Inherited from Z89
  • congenital absence of limbs (Q71-Q73)Inherited from Z89

Code First

Official

No Code First sequencing instructions are included in this display for Z89.449. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for Z89.449. Check the code and parent instructions in the Code Book.

Code Also

Official
  • any follow-up examination (Z08-Z09)Inherited from Z77-Z99

Buddy Documentation Tip

HCC Buddy guidance
Ankle-level amputation documented as acquired
Reason for unspecified laterality noted
Anatomical level at ankle joint specified
Underlying pathology or amputation indication

MEAT Support

HCC Buddy guidance
Ankle-level amputation documented as acquired
Reason for unspecified laterality noted
Anatomical level at ankle joint specified
Underlying pathology or amputation indication

Audit Caution

HCC Buddy guidance
Using when laterality is actually documented
Confusing ankle with foot amputation levels
Not attempting to clarify laterality with provider
Defaulting to unspecified without complete record review

Common Mistakes

HCC Buddy guidance
Z89.441 — Right ankle when laterality is available
Z89.442 — Left ankle when side is documented
Z89.439 — Unspecified foot, different anatomical level
Z89.519 — Unspecified below-knee, higher amputation level

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is Z89.449 an HCC code?

Yes. Z89.449 (Acquired absence of unspecified ankle) maps to HCC 409, Amputation Status, Lower Limb/Amputation Complications under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.598. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: Z89.449 is billable and maps to V28 HCC 409, Amputation Status, Lower Limb/Amputation Complications. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
Z89.449
Description
Acquired absence of unspecified ankle
HCC (V28)
HCC 409 — Amputation Status, Lower Limb/Amputation Complications
RAF reference coefficient
0.598
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 409, Amputation Status, Lower Limb/Amputation Complications
0.598
ESRDHCC 189, Amputation Status/Lower Limb/Amputation Complications
Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work Z89.449 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for Z89.449

For Z89.449, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

  • 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

Coder workflow notes

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What This Code Means

Z89.449 is the ICD-10-CM diagnosis code for acquired absence of unspecified ankle. A person is missing an ankle, but the specific side (left or right) is not documented or is unspecified. Z89.449 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, Z89.449 maps to Amputation Status, Lower Limb/Amputation Complications (HCC 409) with a source-labeled community, non-dual, aged reference coefficient of 0.598. No V24 mapping is shown for Z89.449; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

This is a less specific code; review documentation carefully to determine laterality and assign Z89.441 or Z89.442 if possible. For Z89.449, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for Z89.449 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •This is a less specific code; review documentation carefully to determine laterality and assign Z89.441 or Z89.442 if possible.
  • •Query the provider if laterality is unclear to improve coding specificity and accuracy.

Clinical Significance

Acquired absence of unspecified ankle represents major lower extremity amputation at ankle level when laterality cannot be determined from documentation. Despite incomplete specificity, this indicates severe functional impairment requiring comprehensive amputation care and rehabilitation services.

Documentation Requirements

  • ✓Ankle-level amputation documented as acquired
  • ✓Reason for unspecified laterality noted
  • ✓Anatomical level at ankle joint specified
  • ✓Underlying pathology or amputation indication
  • ✓Current prosthetic status and device type
  • ✓Functional capacity and mobility limitations
  • ✓Rehabilitation services and progress tracking
  • ✓Complications monitoring and prevention

Commonly Confused Codes

  • •Z89.441: Right ankle when laterality is available
  • •Z89.442: Left ankle when side is documented
  • •Z89.439: Unspecified foot, different anatomical level
  • •Z89.519: Unspecified below-knee, higher amputation level
  • •M25.379: Unspecified ankle instability, not amputation

Child Codes

Z89.441Acquired absence of right ankle
HCC 409
Z89.442Acquired absence of left ankle
HCC 409
Z89.449Acquired absence of unspecified ankle
HCC 409

Code Hierarchy

└Z89Acquired absence of limb└Z89.4Acquired absence of toe(s), foot, and ankle└Z89.44Acquired absence of ankle└Z89.449Acquired absence of unspecified ankle
└Z89.449Acquired absence of unspecified ankle

Also searched as

  • Z89 449
  • Z89449

For Z89.449, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

Z89.449 maps to CMS-HCC V28 category 409, Amputation Status, Lower Limb/Amputation Complications. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for Z89.449. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

More on Z89.449

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