2027 ICD-10-CM Diagnosis Code M66.9Spontaneous rupture of unspecified tendon
ICD-10-CM Codes›M00–M99›M65-M67›M66
- Billable — Valid for Submission
- Not Chronic
M66.9 is a billable ICD-10-CM diagnosis code for spontaneous rupture of unspecified tendon. 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. Coders also document this condition as non-traumatic tendon rupture. 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.
- Non-traumatic tendon rupture
- Rupture of tendon
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to M66.9: 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
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Rupture at musculotendinous junction, nontraumatic
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 M66.9, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
tendon (traumatic) See: Strain;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Sprains and Strains
A sprain is a stretched or torn ligament. Ligaments are tissues that connect bones at a joint. Falling, twisting, or getting hit can all cause a sprain. Ankle and wrist sprains are common. Symptoms include pain, swelling, bruising, and being unable to move your joint. You might feel a pop or tear when the injury happens.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M66.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M66.9Overview
What is the ICD-10 code for spontaneous rupture of unspecified tendon?
The ICD-10-CM code for spontaneous rupture of unspecified tendon is M66.9 (sometimes written as M669). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is M66.9 (Spontaneous rupture of synovium and tendon) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report spontaneous rupture of unspecified tendon on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does M66.9 group to?
When spontaneous rupture of unspecified tendon 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 M66.9?
Under the General Equivalence Mappings, spontaneous rupture of unspecified tendon converts to ICD-9-CM 727.60 (nontraum tendon rupt NOS). The mapping is approximate, so confirm the match fits the documentation.
