ICD-10-CM > S00-T88 > S60-S69 > S66 > S66.2 > S66.21 S66.21 Strain of extensor muscle, fascia and tendon of thumb at wrist and hand level Non-Billable/Non-Specific Codes S66.211Strain of extensor muscle, fascia and tendon of right thumb at wrist and hand levelS66.211A..., initial encounterS66.211D..., subsequent encounterS66.211S..., sequelaS66.212Strain of extensor muscle, fascia and tendon of left thumb at wrist and hand levelS66.212A..., initial encounterS66.212D..., subsequent encounterS66.212S..., sequelaS66.219Strain of extensor muscle, fascia and tendon of unspecified thumb at wrist and hand levelS66.219A..., initial encounterS66.219D..., subsequent encounterS66.219S..., sequela