S66.0

⚠ Non-billable (Header)

Injury of long flexor muscle, fascia and tendon of thumb at wrist and hand level

Injury, poisoning and certain other consequences of external causes (S00-T88)

⚠️ This is a category header code — not billable. Use a more specific child code below.

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⚠️ Excludes2

inherited

Rules inherited from parent codes.

S66

• sprain of joints and ligaments of wrist and hand (S63.-)

Child Codes (4)

S66.00Unspecified injury of long flexor muscle, fascia and tendon of thumb at wrist and hand levelHeader S66.01Strain of long flexor muscle, fascia and tendon of thumb at wrist and hand levelHeader S66.02Laceration of long flexor muscle, fascia and tendon of thumb at wrist and hand levelHeader S66.09Other specified injury of long flexor muscle, fascia and tendon of thumb at wrist and hand levelHeader

Clinical Description

ICD-10-CM code S66.0 represents injury of long flexor muscle, fascia and tendon of thumb at wrist and hand level. This code falls under the Injury, poisoning and certain other consequences of external causes (S00-T88) 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.

This is a 5-character code at the 4th level of specificity. There are 4 more specific child codes under S66.0.

Frequently Asked Questions

What is ICD-10 code S66.0?

ICD-10-CM code S66.0 is "Injury of long flexor muscle, fascia and tendon of thumb at wrist and hand level". It belongs to the category: Injury, poisoning and certain other consequences of external causes (S00-T88).

Is S66.0 a billable ICD-10 code?

No, S66.0 is a non-billable header code. A more specific child code must be used for billing.

Can S66.0 be coded with other codes?

S66.0 has 1 Excludes2 note(s). These conditions can be coded together if both are documented in the patient record.

Related Codes in S66

Other codes in the same category that may be relevant for differential coding:

S66.1Injury of flexor muscle, fascia and tendon of other and unspecified finger at wrist and hand level S66.2Injury of extensor muscle, fascia and tendon of thumb at wrist and hand level S66.3Injury of extensor muscle, fascia and tendon of other and unspecified finger at wrist and hand level S66.4Injury of intrinsic muscle, fascia and tendon of thumb at wrist and hand level S66.5Injury of intrinsic muscle, fascia and tendon of other and unspecified finger at wrist and hand level S66.8Injury of other specified muscles, fascia and tendons at wrist and hand level S66.9Injury of unspecified muscle, fascia and tendon at wrist and hand level

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Code Information

CodeS66.0

BillableNo — Header code

ParentS66

CategoryInjury, poisoning and certain other consequences of external causes (S00-T88)

Excludes10 rule(s)

Excludes21 note(s)

Child codes4

Data Source

CMS ICD-10-CM 2026 Tabular List

Updated October 1, 2025 (FY2026)