ICD-10-CM > S00-T88 > S60-S69 > S66 > S66.4 > S66.41 > S66.412 S66.412 Strain of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level Non-Billable/Non-Specific Codes S66.412A..., initial encounterS66.412D..., subsequent encounterS66.412S..., sequela