M66
⚠ Non-billable (Header)Spontaneous rupture of synovium and tendon
Diseases of the musculoskeletal system and connective tissue (M00-M99)
⚠️ This is a category header code — not billable. Use a more specific child code below.
ℹ️ Includes
- • rupture that occurs when a normal force is applied to tissues that are inferred to have less than normal strength
⚠️ Excludes2
directBoth codes can exist if both conditions are documented.
- • rotator cuff syndrome (M75.1-)
- • rupture where an abnormal force is applied to normal tissue - see injury of tendon by body region
Child Codes (6)
Clinical Description
ICD-10-CM code M66 represents spontaneous rupture of synovium and tendon. This code falls under the Diseases of the musculoskeletal system and connective tissue (M00-M99) classification. It is a non-billable category header code. A more specific child code from the list below must be used for billing and reimbursement purposes.
Frequently Asked Questions
What is ICD-10 code M66?
ICD-10-CM code M66 is "Spontaneous rupture of synovium and tendon". It belongs to the category: Diseases of the musculoskeletal system and connective tissue (M00-M99).
Is M66 a billable ICD-10 code?
No, M66 is a non-billable header code. A more specific child code must be used for billing.
Can M66 be coded with other codes?
M66 has 2 Excludes2 note(s). These conditions can be coded together if both are documented in the patient record.
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Data Source
CMS ICD-10-CM 2026 Tabular List
Updated October 1, 2025 (FY2026)