ICD-10-CM > S00-T88 > S50-S59 > S56 > S56.3 > S56.39 S56.39 Other injury of extensor or abductor muscles, fascia and tendons of thumb at forearm level Non-Billable/Non-Specific Codes S56.391Other injury of extensor or abductor muscles, fascia and tendons of right thumb at forearm levelS56.391A..., initial encounterS56.391D..., subsequent encounterS56.391S..., sequelaS56.392Other injury of extensor or abductor muscles, fascia and tendons of left thumb at forearm levelS56.392A..., initial encounterS56.392D..., subsequent encounterS56.392S..., sequelaS56.399Other injury of extensor or abductor muscles, fascia and tendons of unspecified thumb at forearm levelS56.399A..., initial encounterS56.399D..., subsequent encounterS56.399S..., sequela