2026 ICD-10-CM Diagnosis Code M66.271Spontaneous rupture of extensor tendons, right ankle and foot

ICD-10-CM Codes›M00–M99›M65-M67›M66

ICD-10-CM M66.271
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M66.271 is a billable ICD-10-CM diagnosis code for spontaneous rupture of extensor tendons, right ankle and foot. 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. Coders also document this condition as nontraumatic rupture of extensor tendon of foot. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Tendon and synovial disorders.

Code Identity

ICD-10-CM Code
M66.271
Billable Status
Yes — Valid for Submission
Code Describes
Spontaneous rupture of extensor tendons, right ankle and foot
Short Description
Spontaneous rupture of extensor tendons, right ank/ft
Parent Code
M66.27
Spontaneous rupture of extensor tendons, ankle and foot

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM65-M67Disorders of synovium and tendon
CategoryM66Spontaneous rupture of synovium and tendon
This CodeM66.271Spontaneous rupture of extensor tendons, right ankle and foot

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Nontraumatic rupture of extensor tendon of foot
  • Nontraumatic rupture of extensor tendon of right foot
  • Rupture foot extensor tendon

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

Ankle Injuries and Disorders

Your ankle bone and the ends of your two lower leg bones make up the ankle joint. Your ligaments, which connect bones to one another, stabilize and support it. Your muscles and tendons move it.

Read the full article at MedlinePlus

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

Convert M66.271 to ICD-9-CMHistory

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

ICD-9-CM
727.68 Rupture tendon foot NEC
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 M66.271Overview

Is M66.271 (Spontaneous rupture of extensor tendons, ankle and foot) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report spontaneous rupture of extensor tendons, right ankle and foot on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M66.271 group to?

When spontaneous rupture of extensor tendons, right ankle and foot 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 M66.271?

Under the General Equivalence Mappings, spontaneous rupture of extensor tendons, right ankle and foot converts to ICD-9-CM 727.68 (rupture tendon foot NEC). 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.