2026 ICD-10-CM Diagnosis Code M43.23Fusion of spine, cervicothoracic region

ICD-10-CM Codes›M00–M99›M40-M43›M43

ICD-10-CM M43.23
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M43.23 is a billable ICD-10-CM diagnosis code for fusion of spine, cervicothoracic region. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 551 through 552. Coders also document this condition as cervical spine ankylosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Spondylopathies/spondyloarthropathy (including infective).

Code Identity

ICD-10-CM Code
M43.23
Billable Status
Yes — Valid for Submission
Code Describes
Fusion of spine, cervicothoracic region
Short Description
Fusion of spine, cervicothoracic region
Same as the full description in the CMS dataset.
Parent Code
M43.2
Fusion of spine

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM40-M43Deforming dorsopathies
CategoryM43Other deforming dorsopathies
This CodeM43.23Fusion of spine, cervicothoracic region

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Cervical spine ankylosis
  • Cervicothoracic ankylosis
  • Thoracic spine ankylosis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS011
Spondylopathies/spondyloarthropathy (including infective)
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Spine Injuries and Disorders

Your backbone, or spine, is made up of 26 bone discs called vertebrae. The vertebrae protect your spinal cord and allow you to stand and bend. A number of problems can change the structure of the spine or damage the vertebrae and surrounding tissue. They include:

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M43.23 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
724.9 Back disorder NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M43.23Overview

What is the ICD-10 code for fusion of spine, cervicothoracic region?

The ICD-10-CM code for fusion of spine, cervicothoracic region is M43.23 (sometimes written as M4323). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is M43.23 (Fusion of spine) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report fusion of spine, cervicothoracic region on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M43.23 group to?

When fusion of spine, cervicothoracic region is the principal diagnosis on an inpatient stay, it groups to MS-DRG 551, 552, with relative weights from 0.9613 to 1.6761 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M43.23?

Under the General Equivalence Mappings, fusion of spine, cervicothoracic region converts to ICD-9-CM 724.9 (back disorder NOS). The mapping is approximate, so confirm the match fits the documentation.