M66

ICD-10Non-billable category

Spontaneous rupture of synovium and tendon

Official ICD-10-CM descriptor (FY2026)

Spontaneous rupture of synovium and tendon

M66 is a category heading, not a billable code. CMS does not accept it on a claim; report one of the more specific codes beneath it.

Includes

  • 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 condition is not part of this code, but a patient may have both, and both codes may be reported together.

  • rotator cuff syndrome (M75.1-)
  • rupture where an abnormal force is applied to normal tissue - see injury of tendon by body region

More specific codes under M66

Where this code sits

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Source

ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.

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