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M46.23 ICD-10-CM Code: Osteomyelitis of vertebra, cervicothoracic region

M46.23 maps to CMS-HCC V28 92. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools

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Code lookupM46.23

FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Spondylopathies (M45-M49)

M46.23

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

Osteomyelitis of vertebra, cervicothoracic region

A bone infection (osteomyelitis) affecting the vertebrae in the neck and upper back region where the cervical and thoracic spine meet.

Buddy the Bee presenting code insight

Buddy Insight

Osteomyelitis at the cervicothoracic junction is a complex infection requiring multidisciplinary management due to anatomical complexity and risk of complications.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 92

Coefficient HCC 92: 0.479 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 055

Code-level coefficient reference

ESRD/PACE

HCC 39

Code-level coefficient reference

RXHCC

N/A

—

Not mapped

Code Book Path

Official
M46Other inflammatory spondylopathiesM46.2Osteomyelitis of vertebraM46.23Osteomyelitis of vertebra, cervicothoracic region

Inclusion Terms

Official

No inclusion terms are included in this display for M46.23. Check the code and parent instructions in the Code Book.

Excludes 2

Official
  • arthropathic psoriasis (L40.5-)Inherited from M00-M99
  • certain conditions originating in the perinatal period (P04-P96)Inherited from M00-M99
  • certain infectious and parasitic diseases (A00-B99)Inherited from M00-M99
  • compartment syndrome (traumatic) (T79.A-)Inherited from M00-M99
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from M00-M99
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Inherited from M00-M99
  • endocrine, nutritional and metabolic diseases (E00-E88)Inherited from M00-M99
  • injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from M00-M99
  • neoplasms (C00-D49)Inherited from M00-M99
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from M00-M99

Related Codes

Official
M46.20Osteomyelitis of vertebra, site unspecifiedM46.21Osteomyelitis of vertebra, occipito-atlanto-axial regionM46.22Osteomyelitis of vertebra, cervical regionM46.24Osteomyelitis of vertebra, thoracic regionM46.25Osteomyelitis of vertebra, thoracolumbar region

Includes

Official

No Includes notes are included in this display for M46.23. Check the code and parent instructions in the Code Book.

Excludes 1

Official

No Excludes 1 notes are included in this display for M46.23. Check the code and parent instructions in the Code Book.

Code First

Official

No Code First sequencing instructions are included in this display for M46.23. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for M46.23. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for M46.23. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Documentation of bone infection at cervicothoracic junction
Specific identification of involvement spanning cervical-thoracic transition
Imaging studies showing infection across C7-T1 region
Clinical presentation consistent with transitional spine osteomyelitis

MEAT Support

HCC Buddy guidance
Documentation of bone infection at cervicothoracic junction
Specific identification of involvement spanning cervical-thoracic transition
Imaging studies showing infection across C7-T1 region
Clinical presentation consistent with transitional spine osteomyelitis

Audit Caution

HCC Buddy guidance
Using single-region codes when junction involvement is documented
Confusing with pure cervical or thoracic osteomyelitis
Missing documentation of transitional anatomy involvement
Not distinguishing from disc infection at same level

Common Mistakes

HCC Buddy guidance
M4622 — Cervical osteomyelitis affects only cervical vertebrae
M4624 — Thoracic osteomyelitis affects only thoracic vertebrae
M46.33 — Cervicothoracic disc infection affects disc space, not bone
M48.02 — Spinal stenosis at cervicothoracic junction is not infectious

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 M46.23 an HCC code?

Yes. M46.23 (Osteomyelitis of vertebra, cervicothoracic region) maps to HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.479. 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: M46.23 is billable and maps to V28 HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
M46.23
Description
Osteomyelitis of vertebra, cervicothoracic region
HCC (V28)
HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
RAF reference coefficient
0.479
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
0.479
ESRDHCC 39, Bone/Joint/Muscle Infections/Necrosis
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 M46.23 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for M46.23

For M46.23, 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

M46.23 is the ICD-10-CM diagnosis code for osteomyelitis of vertebra, cervicothoracic region. A bone infection (osteomyelitis) affecting the vertebrae in the neck and upper back region where the cervical and thoracic spine meet. M46.23 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering spondylopathies (m45-m49).

Under the CMS-HCC V28 risk adjustment model, M46.23 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis (HCC 92) with a source-labeled community, non-dual, aged reference coefficient of 0.479. 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.

Verify the specific vertebral level documented and confirm this is the cervicothoracic region before assigning this code. For M46.23, 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 M46.23 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Verify the specific vertebral level documented and confirm this is the cervicothoracic region before assigning this code
  • •Ensure documentation supports pyogenic (bacterial) infection; if organism is identified, consider adding an additional code for the specific pathogen

Clinical Significance

Osteomyelitis at the cervicothoracic junction is a complex infection requiring multidisciplinary management due to anatomical complexity and risk of complications. This location poses unique challenges for surgical access and treatment planning.

Documentation Requirements

  • ✓Documentation of bone infection at cervicothoracic junction
  • ✓Specific identification of involvement spanning cervical-thoracic transition
  • ✓Imaging studies showing infection across C7-T1 region
  • ✓Clinical presentation consistent with transitional spine osteomyelitis
  • ✓Laboratory confirmation of infectious process
  • ✓Neurological assessment for cord compression or radiculopathy
  • ✓Documentation of treatment approach and antimicrobial selection
  • ✓Assessment of structural integrity and stability

Commonly Confused Codes

  • •M4622: Cervical osteomyelitis affects only cervical vertebrae
  • •M4624: Thoracic osteomyelitis affects only thoracic vertebrae
  • •M46.33: Cervicothoracic disc infection affects disc space, not bone
  • •M48.02: Spinal stenosis at cervicothoracic junction is not infectious
  • •M54.2: Cervicalgia is pain symptom, not bone infection

Child Codes

M46.20Osteomyelitis of vertebra, site unspecified
HCC 92
M46.21Osteomyelitis of vertebra, occipito-atlanto-axial region
HCC 92
M46.22Osteomyelitis of vertebra, cervical region
HCC 92
M46.23Osteomyelitis of vertebra, cervicothoracic region
HCC 92
M46.24Osteomyelitis of vertebra, thoracic region
HCC 92
M46.25Osteomyelitis of vertebra, thoracolumbar region
HCC 92
M46.26Osteomyelitis of vertebra, lumbar region
HCC 92
M46.27Osteomyelitis of vertebra, lumbosacral region
HCC 92
M46.28Osteomyelitis of vertebra, sacral and sacrococcygeal region
HCC 92

Code Hierarchy

└M46Other inflammatory spondylopathies└M46.2Osteomyelitis of vertebra└M46.23Osteomyelitis of vertebra, cervicothoracic region
└M46.23Osteomyelitis of vertebra, cervicothoracic region

Also searched as

  • M46 23
  • M4623

For M46.23, 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.

M46.23 maps to CMS-HCC V28 category 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for M46.23. 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.

Work M46.23 in HCC Buddy

Open M46.23 in the Code Book for the full Index-to-Tabular path, MEAT checklist, and V28 HCC mapping, or in the Encoder to code from a keyword search. Pro includes 7 days to try everything, no card required.

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