2026 ICD-10-CM Diagnosis Code M51.A1Intervertebral annulus fibrosus defect, small, lumbar region

ICD-10-CM Codes›M00–M99›M50-M54›M51

ICD-10-CM M51.A1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M51.A1 is a billable ICD-10-CM diagnosis code for intervertebral annulus fibrosus defect, small, lumbar 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Low back pain and Spondylopathies/spondyloarthropathy (including infective).

Code Identity

ICD-10-CM Code
M51.A1
Billable Status
Yes — Valid for Submission
Code Describes
Intervertebral annulus fibrosus defect, small, lumbar region
Short Description
Intervertebral annulus fibrosus defect, small, lumbar region
Same as the full description in the CMS dataset.
Parent Code
M51.A
Other lumbar and lumbosacral annulus fibrosus disc defects

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM50-M54Other dorsopathies
CategoryM51Thoracic, thoracolumbar, and lumbosacral intervertebral disc disorders
This CodeM51.A1Intervertebral annulus fibrosus defect, small, lumbar region

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Code First

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
        • lumbar
          • small

Clinical ClassificationClinical

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

CCSR MUS038
Low back pain
Default principal diagnosis: inpatient No · outpatient No
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.

Code History & ChangesHistory

Replacement M51.A1 replaces the following previously assigned code(s):

  • M51.86 - Other intervertebral disc disorders, lumbar region
FY 2023AddedAdded to the ICD-10-CM code setEffective October 1, 2022.
FY 2024–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M51.A1Overview

Is M51.A1 (Other lumbar and lumbosacral annulus fibrosus disc defects) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report intervertebral annulus fibrosus defect, small, lumbar region on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M51.A1 group to?

When intervertebral annulus fibrosus defect, small, lumbar 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.

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.