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).

M46.90 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 40 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 40, ESRD (V21) category 40, and ESRD (V24) category 40 for payment year 2026.

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

Medicare Risk Adjustment (HCC)Billing

M46.90 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
Dropped in V28 see all codes that no longer risk-adjust
Prior Model (CMS-HCC V24)
HCC 40
V24 retired last contributed to a Medicare Advantage risk score in payment year 2025
Other CMS Models
PACE (CMS-HCC V22): HCC 40 · ESRD (V21): HCC 40 · ESRD (V24): HCC 40
ESRD V21 weights: 0.072 dialysis, 0.274–0.398 functioning graft · ESRD V24 weights: 0.058 dialysis, 0.284–0.414 functioning graft
Part D (RxHCC)
Not mapped
M46.90 does not risk-adjust in the RxHCC prescription drug model

Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

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.

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

What is the ICD-10 code for unspecified inflammatory spondylopathy, site unspecified?

The ICD-10-CM code for unspecified inflammatory spondylopathy, site unspecified is M46.90 (sometimes written as M4690). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

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.

Does M46.90 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. M46.90 mapped to HCC 40 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 40 (Rheumatoid Arthritis and Inflammatory Connective Tissue Disease), ESRD (V21) category 40 (Rheumatoid Arthritis and Inflammatory Connective Tissue Disease), and ESRD (V24) category 40 (Rheumatoid Arthritis and Inflammatory Connective Tissue Disease).