2026 ICD-10-CM Diagnosis Code M66.812Spontaneous rupture of other tendons, left shoulder

ICD-10-CM Codes›M00–M99›M65-M67›M66

ICD-10-CM M66.812
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M66.812 is a billable ICD-10-CM diagnosis code for spontaneous rupture of other tendons, left shoulder. 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.

This medical diagnosis code is frequently used in Orthopedics medical specialties to designate conditions such selected shoulder conditions.

Code Identity

ICD-10-CM Code
M66.812
Billable Status
Yes — Valid for Submission
Code Describes
Spontaneous rupture of other tendons, left shoulder
Short Description
Spontaneous rupture of other tendons, left shoulder
Same as the full description in the CMS dataset.
Parent Code
M66.81
Spontaneous rupture of other tendons, shoulder

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM65-M67Disorders of synovium and tendon
CategoryM66Spontaneous rupture of synovium and tendon
This CodeM66.812Spontaneous rupture of other tendons, left shoulder

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral disorder of tendon of shoulders
  • Bilateral tendon disorder of biceps brachii
  • Injury of tendon of long head of left biceps brachii
  • Injury of tendon of long head of right biceps brachii
  • Non-traumatic rupture of biceps brachii tendon
  • Nontraumatic rupture of long head of biceps brachii tendon
  • Nontraumatic rupture of long head of biceps brachii tendon of left shoulder
  • Nontraumatic rupture of long head of biceps brachii tendon of right shoulder
  • Nontraumatic rupture of long head of bilateral biceps brachii tendons
  • Nontraumatic rupture of tendon of bilateral shoulders
  • Nontraumatic rupture of tendon of bilateral upper arms
  • Nontraumatic rupture of tendon of left shoulder
  • Nontraumatic rupture of tendon of left upper arm
  • Nontraumatic rupture of tendon of right shoulder
  • Nontraumatic rupture of tendon of right upper arm
  • Nontraumatic rupture of tendon of shoulder region
  • Nontraumatic rupture of tendon of upper arm
  • Rupture of tendon of biceps, long head
  • Rupture of tendon of left shoulder
  • Rupture of tendon of right shoulder

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

Shoulder Injuries and Disorders

Your shoulder joint is composed of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone). Your shoulders are the most movable joints in your body. They can also be unstable because the ball of the upper arm is larger than the shoulder socket that holds it.

Read the full article at MedlinePlus

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

Convert M66.812 to ICD-9-CMHistory

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

ICD-9-CM
726.10 Rotator cuff synd NOS
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 M66.812Overview

Is M66.812 (Spontaneous rupture of other tendons, shoulder) a billable code?

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

What MS-DRG does M66.812 group to?

When spontaneous rupture of other tendons, left shoulder 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 M66.812?

Under the General Equivalence Mappings, spontaneous rupture of other tendons, left shoulder converts to ICD-9-CM 726.10 (rotator cuff synd NOS). 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.