ICD-10-CM · FY 2026 APRIL UPDATE

S66.4

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

Diagnosis reference

Nonbillable category

This entry is a category or subcategory. Choose the appropriate billable descendant based on the clinical documentation.

Effective periodOctober 1, 2026–September 30, 2027

SourceCMS ICD-10-CM order file

ClassificationDiagnosis · clinical modification

Related entries

Up to 30 descendants in this category

CODE	DESCRIPTION	TYPE
S66.40	Unspecified injury of intrinsic muscle, fascia and tendon of thumb at wrist and hand level	Category
S66.401	Unspecified injury of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level	Category
S66.401A	Unspecified injury of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, initial encounter	Billable
S66.401D	Unspecified injury of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, subsequent encounter	Billable
S66.401S	Unspecified injury of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, sequela	Billable
S66.402	Unspecified injury of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level	Category
S66.402A	Unspecified injury of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level, initial encounter	Billable
S66.402D	Unspecified injury of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level, subsequent encounter	Billable
S66.402S	Unspecified injury of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level, sequela	Billable
S66.409	Unspecified injury of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level	Category
S66.409A	Unspecified injury of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, initial encounter	Billable
S66.409D	Unspecified injury of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, subsequent encounter	Billable
S66.409S	Unspecified injury of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, sequela	Billable
S66.41	Strain of intrinsic muscle, fascia and tendon of thumb at wrist and hand level	Category
S66.411	Strain of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level	Category
S66.411A	Strain of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, initial encounter	Billable
S66.411D	Strain of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, subsequent encounter	Billable
S66.411S	Strain of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, sequela	Billable
S66.412	Strain of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level	Category
S66.412A	Strain of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level, initial encounter	Billable
S66.412D	Strain of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level, subsequent encounter	Billable
S66.412S	Strain of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level, sequela	Billable
S66.419	Strain of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level	Category
S66.419A	Strain of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, initial encounter	Billable
S66.419D	Strain of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, subsequent encounter	Billable
S66.419S	Strain of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, sequela	Billable
S66.42	Laceration of intrinsic muscle, fascia and tendon of thumb at wrist and hand level	Category
S66.421	Laceration of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level	Category
S66.421A	Laceration of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, initial encounter	Billable
S66.421D	Laceration of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, subsequent encounter	Billable

Use the complete reference

This reference does not reproduce the full tabular hierarchy, inclusion notes, Excludes1/2 notes, sequencing instructions, or seventh-character rules. Review the official tables and coding guidelines.

Open official CMS files

ICD-10-CM codes describe diagnoses. They do not have an independent Medicare PFS reimbursement amount, and billability alone does not establish coverage.