ICD-10 M66
Non-Billable HeaderSpontaneous rupture of synovium and tendon
About ICD-10-CM M66
ICD-10-CM code M66 represents Spontaneous rupture of synovium and tendon. This is a non-billable header code in the Musculoskeletal and Connective Tissue chapter (block M66). The 2026 edition of ICD-10-CM M66 became effective on October 1, 2025. Non-billable codes cannot be used as a primary or secondary diagnosis on a claim, use a more specific child code instead.
Type 2 Excludes
Not included here, the excluded code is not part of M66, but a patient may have both conditions at the same time. Both codes may be coded together when applicable.
- rotator cuff syndrome (M75.1-)
- rupture where an abnormal force is applied to normal tissue - see injury of tendon by body region
Includes
- rupture that occurs when a normal force is applied to tissues that are inferred to have less than normal strength
Medicare LCD Coverage for M66
Local Coverage Determinations (LCDs) from CMS MACs that list M66 as a covered diagnosis.
This doesn't mean the code isn't covered, it means no MAC has issued a Local Coverage Determination naming this specific code. Coverage may still apply under National Coverage Determinations or general medical-necessity rules.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing M66.
Our payer policy database covers Aetna, Cigna, Anthem, BCBS, Humana, and Medicare Advantage plans, but M66 doesn't currently appear in any indexed policy. The code may still be covered under standard plan benefits.
CPT Codes Commonly Billed with M66
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Codes Adjacent To M66
Other codes in section M65-M67 (Disorders of synovium and tendon).
ICD-10 M66, Billing FAQ
Is ICD-10 code M66 billable? +
No, M66 is a non-billable header code. Use a more specific child code from block M66 when submitting claims.
What codes are Type 2 Excludes for M66? +
Type 2 Excludes (may be coded together when both conditions exist): rotator cuff syndrome (M75.1-); rupture where an abnormal force is applied to normal tissue - see injury of tendon by body region
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on June 1, 2026.
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