2026 ICD-10-CM Diagnosis Code M66.862Spontaneous rupture of other tendons, left lower leg

ICD-10-CM Codes›M00–M99›M65-M67›M66

ICD-10-CM M66.862
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M66.862 is a billable ICD-10-CM diagnosis code for spontaneous rupture of other tendons, left lower 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
M66.862
Billable Status
Yes — Valid for Submission
Code Describes
Spontaneous rupture of other tendons, left lower leg
Short Description
Spontaneous rupture of other tendons, left lower leg
Same as the full description in the CMS dataset.
Parent Code
M66.86
Spontaneous rupture of other tendons, lower leg

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM65-M67Disorders of synovium and tendon
CategoryM66Spontaneous rupture of synovium and tendon
This CodeM66.862Spontaneous rupture of other tendons, left lower leg

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral nontraumatic plantaris tendon rupture
  • Injury of left Achilles tendon
  • Injury of posterior crural muscle of left lower leg
  • Injury of posterior crural muscle of right lower leg
  • Injury of right Achilles tendon
  • Nontraumatic plantaris tendon rupture
  • Non-traumatic rupture of Achilles tendon
  • Nontraumatic rupture of bilateral Achilles tendons
  • Nontraumatic rupture of bilateral patellar tendons
  • Nontraumatic rupture of left Achilles tendon
  • Nontraumatic rupture of left plantaris tendon
  • Nontraumatic rupture of left quadriceps tendon
  • Nontraumatic rupture of muscle
  • Non-traumatic rupture of patellar tendon
  • Nontraumatic rupture of quadriceps tendon
  • Nontraumatic rupture of right Achilles tendon
  • Nontraumatic rupture of right plantaris tendon
  • Nontraumatic rupture of right quadriceps tendon
  • Nontraumatic rupture of tendon of bilateral lower legs
  • Nontraumatic rupture of tendon of bilateral quadriceps muscles
  • Nontraumatic rupture of tendon of left lower leg
  • Nontraumatic rupture of tendon of left patella
  • Nontraumatic rupture of tendon of right lower leg
  • Nontraumatic rupture of tendon of right patella
  • Rupture of Achilles tendon
  • Rupture of left Achilles tendon
  • Rupture of left plantaris tendon
  • Rupture of patellar tendon
  • Rupture of plantaris tendon
  • Rupture of right Achilles tendon
  • Rupture of right plantaris 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

Leg Injuries and Disorders

Your legs are made up of bones, blood vessels, muscles, and other connective tissue. They are important for motion and standing. Playing sports, running, falling, or having an accident can damage your legs. Common leg injuries include sprains and strains, joint dislocations, and fractures (broken bones).

Read the full article at MedlinePlus

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

Convert M66.862 to ICD-9-CMHistory

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

ICD-9-CM
727.67 Rupture achilles tendon
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 M66.862Overview

Is M66.862 (Spontaneous rupture of other tendons, lower leg) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report spontaneous rupture of other tendons, left lower leg on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M66.862 group to?

When spontaneous rupture of other tendons, left lower 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 M66.862?

Under the General Equivalence Mappings, spontaneous rupture of other tendons, left lower leg converts to ICD-9-CM 727.67 (rupture achilles tendon). 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.