2026 ICD-10-CM Diagnosis Code M77.9Enthesopathy, unspecified

ICD-10-CM Codes›M00–M99›M70-M79›M77

ICD-10-CM M77.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M77.9 is a billable ICD-10-CM diagnosis code for enthesopathy, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 557 through 558. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Tendon and synovial disorders.

Code Identity

ICD-10-CM Code
M77.9
Billable Status
Yes — Valid for Submission
Code Describes
Enthesopathy, unspecified
Short Description
Enthesopathy, unspecified
Same as the full description in the CMS dataset.
Parent Code
M77
Other enthesopathies

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM70-M79Other soft tissue disorders
CategoryM77Other enthesopathies
This CodeM77.9Enthesopathy, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute calcific periarthritis
  • Bilateral enthesopathy of shoulders
  • Capsulitis
  • Capsulitis of metatarsophalangeal joint of left foot
  • Capsulitis of metatarsophalangeal joint of right foot
  • Capsulitis of tarsus
  • Enthesopathy
  • Enthesopathy of foot region
  • Enthesopathy of left elbow
  • Enthesopathy of left finger
  • Enthesopathy of left foot
  • Enthesopathy of left hand
  • Enthesopathy of left shoulder region
  • Enthesopathy of pelvic region
  • Enthesopathy of right elbow
  • Enthesopathy of right foot
  • Enthesopathy of right shoulder region
  • Enthesopathy of shoulder region
  • Enthesopathy of upper limb
  • Enthesopathy of wrist and/or hand
  • Periarthritis
  • Tarsus enthesopathy
  • Tendinitis
  • Tendinitis of extensor tendon of left hand
  • Tendinitis of extensor tendon of right hand
  • Tendinitis of flexor tendon of left hand
  • Tendinitis of flexor tendon of right hand
  • Tendinitis of left foot
  • Tendinitis of right foot
  • Tendonitis of bilateral forearms

Tabular List NotesGuidance

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

Inclusion Terms

  • Bone spur NOS
  • Capsulitis NOS
  • Periarthritis NOS
  • Tendinitis NOS

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.

    • Enthesopathy(peripheral)

Clinical ClassificationClinical

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

CCSR MUS009
Tendon and synovial disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Enthesopathy

    a disorder occurring at the site of insertion of tendons or ligaments into bones or joint capsules.

  • Periarthritis

    inflammation of the tissues around a joint. (dorland, 27th ed)

Patient EducationClinical

Connective Tissue Disorders

Your connective tissue supports many different parts of your body, such as your skin, eyes, and heart. It is like a "cellular glue" that gives your body parts their shape and helps keep them strong. It also helps some of your tissues do their work. It is made of many kinds of proteins. Cartilage and fat are types of connective tissue.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M77.9 to ICD-9-CMHistory

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

ICD-9-CM
726.90 Enthesopathy, site NOS
Exact Match The mapping is direct, with no qualifiers.

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 M77.9Overview

Is M77.9 (Other enthesopathies) a billable code?

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

What MS-DRG does M77.9 group to?

When enthesopathy, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 557, 558, with relative weights from 0.8932 to 1.4869 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M77.9?

Under the General Equivalence Mappings, enthesopathy, unspecified converts to ICD-9-CM 726.90 (enthesopathy, site NOS). The mapping is a direct match.

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.