2026 ICD-10-CM Diagnosis Code M51.9Unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder

ICD-10-CM Codes›M00–M99›M50-M54›M51

ICD-10-CM M51.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M51.9 is a billable ICD-10-CM diagnosis code for unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Spondylopathies/spondyloarthropathy (including infective).

This medical diagnosis code is frequently used in Orthopedics medical specialties to designate conditions such thoracic, thoracolumbar, and lumbosacral intervertebral disc disorders.

Code Identity

ICD-10-CM Code
M51.9
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder
Short Description
Unsp thoracic, thoracolum and lumbosacr intvrt disc disorder
Parent Code
M51
Thoracic, thoracolumbar, and lumbosacral intervertebral disc disorders

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM50-M54Other dorsopathies
CategoryM51Thoracic, thoracolumbar, and lumbosacral intervertebral disc disorders
This CodeM51.9Unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Degeneration of intervertebral disc
  • Disc prolapse with radiculopathy
  • Disorder of intervertebral disc of thoracic spine
  • Disorder of lumbar disc
  • Disorder of lumbosacral intervertebral disc
  • Intervertebral disc disorder
  • Intervertebral disc prolapse
  • Intervertebral disk calcification
  • Lordosis deformity of spine due to degenerative disc disease
  • Myelopathy due to intervertebral disc disease
  • Prolapsed intervertebral disc without myelopathy
  • Thoracolumbar disc disorder

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.

    • Defect, defective
      • intervertebral annular fibrosis
    • Disorder(of)
      • disc (intervertebral)
    • Neuritis(rheumatoid)
      • due to
        • herniation, nucleus pulposus

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 M51.9 to ICD-9-CMHistory

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

ICD-9-CM
722.90 Disc dis NEC/NOS-unspec
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 M51.9Overview

Is M51.9 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M51.9 group to?

When unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder 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 M51.9?

Under the General Equivalence Mappings, unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder converts to ICD-9-CM 722.90 (disc dis NEC/NOS-unspec). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.