ICD-10-CM > S00-T88 > S60-S69 > S66 > S66.0 > S66.01 S66.01 Strain of long flexor muscle, fascia and tendon of thumb at wrist and hand level Non-Billable/Non-Specific Codes S66.011Strain of long flexor muscle, fascia and tendon of right thumb at wrist and hand levelS66.011A..., initial encounterS66.011D..., subsequent encounterS66.011S..., sequelaS66.012Strain of long flexor muscle, fascia and tendon of left thumb at wrist and hand levelS66.012A..., initial encounterS66.012D..., subsequent encounterS66.012S..., sequelaS66.019Strain of long flexor muscle, fascia and tendon of unspecified thumb at wrist and hand levelS66.019A..., initial encounterS66.019D..., subsequent encounterS66.019S..., sequela