ICD-10-CM > S00-T88 > S60-S69 > S66 > S66.4 > S66.42 S66.42 Laceration of intrinsic muscle, fascia and tendon of thumb at wrist and hand level Non-Billable/Non-Specific Codes S66.421Laceration of intrinsic muscle, fascia and tendon of right thumb at wrist and hand levelS66.421A..., initial encounterS66.421D..., subsequent encounterS66.421S..., sequelaS66.422Laceration of intrinsic muscle, fascia and tendon of left thumb at wrist and hand levelS66.422A..., initial encounterS66.422D..., subsequent encounterS66.422S..., sequelaS66.429Laceration of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand levelS66.429A..., initial encounterS66.429D..., subsequent encounterS66.429S..., sequela