M99.08 ICD-10-CM Code: Segmental and somatic dysfunction of rib cage
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FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Biomechanical lesions, not elsewhere classified (M99)
M99.08
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceSegmental and somatic dysfunction of rib cage
A dysfunction of the ribs and surrounding structures where bones and joints are misaligned, potentially causing chest pain or breathing difficulties.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
00
RAF 0
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Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for M99.08 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M99.08 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M99.08 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M99.08 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M99.08 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M99.08 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M99.08 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 M99.08 an HCC code?
No. M99.08 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
M99.08 is the ICD-10-CM diagnosis code for segmental and somatic dysfunction of rib cage. A dysfunction of the ribs and surrounding structures where bones and joints are misaligned, potentially causing chest pain or breathing difficulties. M99.08 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering biomechanical lesions, not elsewhere classified (m99).
M99.08 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.
This condition may present with chest wall pain; ensure it's not confused with cardiac or pulmonary conditions.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M99.08 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This condition may present with chest wall pain; ensure it's not confused with cardiac or pulmonary conditions
- •Document which ribs are affected and whether the dysfunction is unilateral or bilateral