2027 ICD-10-CM Diagnosis Code M66.861Spontaneous rupture of other tendons, right lower leg
ICD-10-CM Codes›M00–M99›M65-M67›M66
- Billable — Valid for Submission
- Not Chronic
M66.861 is a billable ICD-10-CM diagnosis code for spontaneous rupture of other tendons, right lower leg. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) 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
Code Classification
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 feet
- Nontraumatic rupture of tendon of bilateral lower legs
- Nontraumatic rupture of tendon of bilateral quadriceps muscles
- Nontraumatic rupture of tendon of left foot
- Nontraumatic rupture of tendon of left lower leg
- Nontraumatic rupture of tendon of left patella
- Nontraumatic rupture of tendon of right foot
- 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
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to M66.861: its own notes plus those printed at M66 and Chapter 13. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- rupture that occurs when a normal force is applied to tissues that are inferred to have less than normal strength
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- rotator cuff syndrome (M75.1-)
- rupture where an abnormal force is applied to normal tissue - see injury of tendon by body region
- arthropathic psoriasis (L40.5-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- compartment syndrome (traumatic) (T79.A-)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Notes
General instructions on how these codes are used.
- Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name M66.861, its category, or a range that includes it.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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 M66.861 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M66.861Overview
What is the ICD-10 code for spontaneous rupture of other tendons, right lower leg?
The ICD-10-CM code for spontaneous rupture of other tendons, right lower leg is M66.861 (sometimes written as M66861). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is M66.861 (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, right lower leg on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does M66.861 group to?
When spontaneous rupture of other tendons, right lower leg is the principal diagnosis on an inpatient stay, it groups to MS-DRG 557, 558, with relative weights from 0.8873 to 1.4883 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of M66.861?
Under the General Equivalence Mappings, spontaneous rupture of other tendons, right lower leg converts to ICD-9-CM 727.67 (rupture achilles tendon). The mapping is approximate, so confirm the match fits the documentation.
