2026 ICD-10-CM Diagnosis Code M46.90Unspecified inflammatory spondylopathy, site unspecified

ICD-10-CM Codes›M00–M99›M45-M49›M46

ICD-10-CM M46.90
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M46.90 is a billable ICD-10-CM diagnosis code for unspecified inflammatory spondylopathy, site unspecified. 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 arthritis of spine. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Spondylopathies/spondyloarthropathy (including infective).

Code Identity

ICD-10-CM Code
M46.90
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified inflammatory spondylopathy, site unspecified
Short Description
Unspecified inflammatory spondylopathy, site unspecified
Same as the full description in the CMS dataset.
Parent Code
M46.9
Unspecified inflammatory spondylopathy

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM45-M49Spondylopathies
CategoryM46Other inflammatory spondylopathies
This CodeM46.90Unspecified inflammatory spondylopathy, site unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Arthritis of spine
  • Infection causing spondyloarthritis
  • Peripheral spondyloarthritis
  • Spondylitis
  • Undifferentiated spondylitis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Spondylopathy
      • inflammatory

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

Clinical InformationClinical

  • Spondylarthropathies

    heterogeneous group of arthritic diseases sharing clinical and radiologic features. they are associated with the hla-b27 antigen and some with a triggering infection. most involve the axial joints in the spine, particularly the sacroiliac joint, but can also involve asymmetric peripheral joints. subsets include ankylosing spondylitis; reactive arthritis; psoriatic arthritis; and others.

  • Spondylitis

    inflammation of the spine. this includes both arthritic and non-arthritic conditions.

  • Spondylitis, Ankylosing

    a chronic inflammatory condition affecting the axial joints, such as the sacroiliac joint and other intervertebral or costovertebral joints. it occurs predominantly in young males and is characterized by pain and stiffness of joints (ankylosis) with inflammation at tendon insertions.

  • Spine

    the spinal or vertebral column.

  • Ankylosing Spondylitis of Cervical Region|Ankylosing spondylitis of cervical region

    evidence of ankylosing spondylitis of cervical region.

  • Ankylosing Spondylitis of Cervicothoracic Region|Ankylosing spondylitis of cervicothoracic region

    evidence of ankylosing spondylitis of cervicothoracic region.

  • Ankylosing Spondylitis of Lumbar Region|Ankylosing spondylitis lumbar region

    evidence of ankylosing spondylitis of lumbar region.

  • Ankylosing Spondylitis of Lumbosacral Region|Ankylosing spondylitis of lumbosacral region

    evidence of ankylosing spondylitis of lumbosacral region.

  • Ankylosing Spondylitis of Multiple Sites in Spine|Ankylosing spondylitis of multiple sites in spine

    evidence of ankylosing spondylitis of multiple sites in spine.

  • Ankylosing Spondylitis of Occipito-Atlanto-Axial Region|Ankylosing spondylitis of occipito-atlanto-axial region

    evidence of ankylosing spondylitis of occipito-atlanto-axial region.

  • Ankylosing Spondylitis of Thoracic Region|Ankylosing spondylitis of thoracic region

    evidence of ankylosing spondylitis of thoracic region.

  • Ankylosing Spondylitis of Thoracolumbar Region|Ankylosing spondylitis of thoracolumbar region

    evidence of ankylosing spondylitis of thoracolumbar region.

  • Ankylosing Spondylitis Sacral and Sacrococcygeal Region|Ankylosing spondylitis sacral and sacrococcygeal region

    evidence of ankylosing spondylitis sacral and sacrococcygeal region.

  • Ankylosing Spondylitis|Ankylosing spondylitis of unspecified sites in spine

    an autoimmune chronic inflammatory disorder characterized by inflammation in the vertebral joints of the spine and sacroiliac joints. it predominantly affects young males. patients present with stiffness and pain in the spine.

  • Bath Ankylosing Spondylitis Disease Activity Index|BASDAI|BASDAI

    a clinical index used to assess the activity of ankylosing spondylitis that has been validated in adults.

  • Enteropathic Spondylitis|Enteropathic Spondyloarthritis

    a form of spondyloarthritis that is found in some patients with inflammatory bowel disease.

  • Juvenile Ankylosing Spondylitis|Juvenile ankylosing spondylitis

    ankylosing spondylitis occurring in children or adolescents.

  • Spondylitis

    the inflammation of a vertebra.

  • Spondyloarthritis|Seronegative Spondyloarthropathy|Spondylitis|Spondylitis|Spondyloarthropathy

    a group of inflammatory rheumatic diseases associated with arthritis and enthesitis, and often involving the axial skeleton. the most common form of spondyloarthritis is ankylosing spondylitis. other forms include axial spondyloarthritis, peripheral spondyloarthritis, reactive arthritis, psoriatic arthritis/spondylitis and enteropathic arthritis/spondylitis.

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 M46.90 to ICD-9-CMHistory

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

ICD-9-CM
720.9 Inflam spondylopathy 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 M46.90Overview

Is M46.90 (Unspecified inflammatory spondylopathy) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified inflammatory spondylopathy, site unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M46.90 group to?

When unspecified inflammatory spondylopathy, site unspecified 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 M46.90?

Under the General Equivalence Mappings, unspecified inflammatory spondylopathy, site unspecified converts to ICD-9-CM 720.9 (inflam spondylopathy NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.