ICD-10-CM > S00-T88 > S50-S59 > S56 > S56.4 > S56.41 > S56.412 S56.412 Strain of extensor muscle, fascia and tendon of left index finger at forearm level Non-Billable/Non-Specific Codes S56.412A..., initial encounterS56.412D..., subsequent encounterS56.412S..., sequela