2026 ICD-10-CM Diagnosis Code M76.821Posterior tibial tendinitis, right leg

ICD-10-CM Codes›M00–M99›M70-M79›M76

ICD-10-CM M76.821
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M76.821 is a billable ICD-10-CM diagnosis code for posterior tibial tendinitis, right leg. 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
M76.821
Billable Status
Yes — Valid for Submission
Code Describes
Posterior tibial tendinitis, right leg
Short Description
Posterior tibial tendinitis, right leg
Same as the full description in the CMS dataset.
Parent Code
M76.82
Posterior tibial tendinitis

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM70-M79Other soft tissue disorders
CategoryM76Enthesopathies, lower limb, excluding foot
This CodeM76.821Posterior tibial tendinitis, right leg

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral tendinitis of feet
  • Disorder of posterior tibial muscle tendon
  • Tendinitis of bilateral posterior tibialis muscles
  • Tendinitis of left foot
  • Tendinitis of left posterior tibial tendon
  • Tendinitis of right foot
  • Tendinitis of right posterior tibial tendon
  • Tibialis posterior tendinitis
  • Tibialis tendinitis

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

Patient EducationClinical

Tendinitis

Tendons are flexible bands of tissue that connect muscles to bones. They help your muscles move your bones. Tendinitis is the severe swelling of a tendon.

Read the full article at MedlinePlus

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

Convert M76.821 to ICD-9-CMHistory

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

ICD-9-CM
726.72 Tibialis tendinitis
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 M76.821Overview

Is M76.821 (Posterior tibial tendinitis) a billable code?

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

What MS-DRG does M76.821 group to?

When posterior tibial tendinitis, right leg 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 M76.821?

Under the General Equivalence Mappings, posterior tibial tendinitis, right leg converts to ICD-9-CM 726.72 (tibialis tendinitis). The mapping is approximate, so confirm the match fits the documentation.

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.