ICD-10-CM > S00-T88 > S50-S59 > S56 > S56.3 > S56.31 S56.31 Strain of extensor or abductor muscles, fascia and tendons of thumb at forearm level Non-Billable/Non-Specific Codes S56.311Strain of extensor or abductor muscles, fascia and tendons of right thumb at forearm levelS56.311A..., initial encounterS56.311D..., subsequent encounterS56.311S..., sequelaS56.312Strain of extensor or abductor muscles, fascia and tendons of left thumb at forearm levelS56.312A..., initial encounterS56.312D..., subsequent encounterS56.312S..., sequelaS56.319Strain of extensor or abductor muscles, fascia and tendons of unspecified thumb at forearm levelS56.319A..., initial encounterS56.319D..., subsequent encounterS56.319S..., sequela