ICD-10-CM > S00-T88 > S50-S59 > S56 > S56.0 > S56.01 > S56.019 S56.019 Strain of flexor muscle, fascia and tendon of unspecified thumb at forearm level Non-Billable/Non-Specific Codes S56.019A..., initial encounterS56.019D..., subsequent encounterS56.019S..., sequela