M89.364 ICD-10-CM Code: Hypertrophy of bone, left fibula
HCC Buddy Code Card
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FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Other osteopathies (M86-M90)
M89.364
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceHypertrophy of bone, left fibula
Abnormal thickening and enlargement of the bone in the left fibula (the smaller bone in the lower leg).
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for M89.364 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M89.364 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M89.364 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M89.364 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M89.364 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M89.364 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M89.364 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is M89.364 an HCC code?
No. M89.364 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
- Code
- M89.364
- Description
- Hypertrophy of bone, left fibula
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF
- —
- Billable
- Yes
- Payment year
- 2026
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
M89.364 is the ICD-10-CM diagnosis code for hypertrophy of bone, left fibula. Abnormal thickening and enlargement of the bone in the left fibula (the smaller bone in the lower leg). M89.364 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering other osteopathies (m86-m90).
M89.364 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Confirm left-sided involvement is documented in the clinical notes before coding.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M89.364 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm left-sided involvement is documented in the clinical notes before coding
- •Do not use this code if the fibula involvement is bilateral; use M89.369 instead