2026 ICD-10-CM Diagnosis Code M48.18Ankylosing hyperostosis [Forestier], sacral and sacrococcygeal region

ICD-10-CM Codes›M00–M99›M45-M49›M48

ICD-10-CM M48.18
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M48.18 is a billable ICD-10-CM diagnosis code for ankylosing hyperostosis [Forestier], sacral and sacrococcygeal 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 Spondylopathies/spondyloarthropathy (including infective).

Code Identity

ICD-10-CM Code
M48.18
Billable Status
Yes — Valid for Submission
Code Describes
Ankylosing hyperostosis [Forestier], sacral and sacrococcygeal region
Short Description
Ankylosing hyperostosis, sacral and sacrococcygeal region
Parent Code
M48.1
Ankylosing hyperostosis [Forestier]

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM45-M49Spondylopathies
CategoryM48Other spondylopathies
This CodeM48.18Ankylosing hyperostosis [Forestier], sacral and sacrococcygeal region

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.

    • Hyperostosis(monomelic)
      • ankylosing (spine)
        • sacrococcygeal region

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 M48.18 to ICD-9-CMHistory

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

ICD-9-CM
721.6 Ankyl vert hyperostosis
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 M48.18Overview

Is M48.18 (Ankylosing hyperostosis [Forestier]) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report ankylosing hyperostosis [Forestier], sacral and sacrococcygeal region on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M48.18 group to?

When ankylosing hyperostosis [Forestier], sacral and sacrococcygeal 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 M48.18?

Under the General Equivalence Mappings, ankylosing hyperostosis [Forestier], sacral and sacrococcygeal region converts to ICD-9-CM 721.6 (ankyl vert hyperostosis). 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.