2026 ICD-10-CM Diagnosis Code M76.51Patellar tendinitis, right knee

ICD-10-CM Codes›M00–M99›M70-M79›M76

ICD-10-CM M76.51
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M76.51 is a billable ICD-10-CM diagnosis code for patellar tendinitis, right knee. 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
M76.51
Billable Status
Yes — Valid for Submission
Code Describes
Patellar tendinitis, right knee
Short Description
Patellar tendinitis, right knee
Same as the full description in the CMS dataset.
Parent Code
M76.5
Patellar tendinitis

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM70-M79Other soft tissue disorders
CategoryM76Enthesopathies, lower limb, excluding foot
This CodeM76.51Patellar tendinitis, right knee

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral tendinitis of knees
  • Bilateral tendinitis of quadriceps tendon
  • Inflammation of ligament
  • Patellar tendonitis
  • Tendinitis of left knee
  • Tendinitis of left patellar tendon
  • Tendinitis of left quadriceps tendon
  • Tendinitis of right knee
  • Tendinitis of right patellar tendon
  • Tendinitis of right quadriceps tendon
  • Tendonitis of bilateral patellar tendons

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 M76.51 to ICD-9-CMHistory

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

ICD-9-CM
726.64 Patellar 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 M76.51Overview

Is M76.51 (Patellar tendinitis) a billable code?

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

What MS-DRG does M76.51 group to?

When patellar tendinitis, right knee 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 M76.51?

Under the General Equivalence Mappings, patellar tendinitis, right knee converts to ICD-9-CM 726.64 (patellar 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.