ICD-10-CM > S00-T88 > S60-S69 > S66 > S66.4 > S66.40 > S66.409 S66.409 Unspecified injury of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level Non-Billable/Non-Specific Codes S66.409A..., initial encounterS66.409D..., subsequent encounterS66.409S..., sequela